Interfacial Synergetic Integration of Graphitic Carbon Nitride-Polypyrrole Anchored on Carbon Nanorod for Efficient Water Electrolysis

Interfacial Synergetic Integration of Graphitic Carbon Nitride-Polypyrrole Anchored on Carbon Nanorod for Efficient Water Electrolysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Interfacial Synergetic Integration of Graphitic Carbon Nitride-Polypyrrole Anchored on Carbon Nanorod for Efficient Water Electrolysis Anup Kumar Pradhan, Amrutha Radhakrishnan, Anirban Biswas, Sankar Ganesh Palani, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8005480/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Hydrogen generation from electrolysis of water is one of the most sustainable strategies for clean energy conversion. However, the sluggish kinetics of oxygen and hydrogen evolution limit its practical implementation. Developing an efficient, low-cost, and durable bifunctional electrocatalyst for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is always in demand for promoting clean energy from water. In this work, we report a unique metal-free electrocatalyst composed of graphitic carbon nitride-polypyrrole on carbon nanorods (g-C 3 N 4 -Ppy/CR) for efficient water electrocatalysis. The above electrocatalyst was synthesized by depositing g-C 3 N 4 -Ppy on the surface of a metal-organic framework-derived carbon nanorod (CR). The unique heterointerface of the electrocatalyst endows it with outstanding bifunctional activity, requiring overpotentials of only 355 mV and 187 mV to achieve 10 mA cm − 2 current density with a small Tafel slope of 86 mV dec − 1 and 105 mV dec − 1 for OER and HER, respectively. The chronoamperometric performance further confirmed the long-term stability of the electrocatalyst, with over 50 hours of continuous operation maintained. Moreover, owing to the excellent OER and HER performance in alkaline media, the overall water splitting was carried out by using a two-electrode system. A cell voltage of 1.8 V was sufficient to achieve a current density of 10 mA cm − 2 , which is only 0.07 V higher than the commercially available catalyst-modified cell. The g-C 3 N 4 -Ppy/CR-modified cell also has excellent stability at a higher current density of 3.1 mA cm − 2 . These results highlight the synergistic interplay between the components and provide a promising strategy for designing new ternary electrocatalysts toward efficient overall water splitting and renewable hydrogen production. Metal-free electrocatalyst Hydrogen evolution reaction (HER) Oxygen evolution reaction (OER) Polypyrrole Graphitic carbon nitride Water electrolysis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Over the past decade, global energy demand has surged dramatically, primarily due to rapid population growth and accelerated industrialization [1–3]. Currently, conventional fossil fuels, such as coal, oil, and natural gas, still account for more than 60% of the world’s total energy needs, whereas renewable sources, including solar, wind, tidal, and geothermal energy, contribute less than 40%. This heavy dependence on fossil fuels not only accelerates their depletion but also leads to critical environmental issues, including air pollution, global warming, and ecosystem degradation. Hence, the transition toward renewable and environmentally sustainable energy sources has become a pressing global necessity to ensure long-term energy security and ecological balance. Among the various clean energy carriers, hydrogen has garnered considerable attention as a next-generation fuel due to its high energy density, abundance, and zero-emission characteristics [4–7]. Currently, most hydrogen is produced through methane steam reforming, a process that is limited by low energy efficiency and high carbon dioxide emissions. To overcome these drawbacks, alternative approaches such as thermal catalysis, photocatalysis, and electrocatalysis have been widely explored for sustainable hydrogen production through water splitting. Electrocatalytic water splitting stands out as one of the most efficient and environmentally friendly routes for hydrogen generation. This technique utilizes electrical energy to decompose water into hydrogen and oxygen, and can be seamlessly integrated with renewable power sources such as wind and solar energy, thereby enhancing the overall efficiency of sustainable energy systems. The process involves two half-reactions: the oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction (HER) at the cathode. Since HER plays a decisive role in determining the efficiency and cost-effectiveness of hydrogen production, designing highly active, stable, and low-cost HER electrocatalysts has become a major research focus in the field of energy materials and electrochemistry [8–12]. Graphitic carbon nitride (g-C₃N₄) is a layered compound composed of sp²-hybridized carbon and nitrogen atoms arranged in a graphite-like framework. It has gained significant attention as a promising catalyst owing to its high nitrogen content, large surface area, and abundance of active sites [13–16]. Its well-defined electronic structure, excellent thermal stability, and tunable active centers make it particularly effective for electrocatalysis [13–14]. To overcome its limited electrical conductivity, researchers have sought to modify the electronic structure of g-C₃N₄ by tailoring metal–nitrogen coordination sites (M–N₄) [17–18]. Furthermore, strategies such as elemental doping and heterojunction construction have been demonstrated to enhance charge transport and structural stability, thereby broadening the potential of g-C₃N₄ for high-performance catalytic applications [18]. Nitrogen-rich, metal-free conducting polymers, such as polypyrrole and polyaniline, hold great promise for developing efficient metal-free electrocatalysts for the HER and OER through overall water splitting [19]. The formation of heterojunctions with these polymers can enhance their chemical stability, expose more active sites, and improve electrical conductivity, all of which are crucial for accelerating HER and OER kinetics [19]. Hongli An et al. reported a core–shell hybrid structure of polypyrrole and carbon nanotubes (CNTs), which exhibited superior charge transport and an increased number of catalytic sites, leading to enhanced electrocatalytic activity [20]. Furthermore, incorporating such heterostructures onto high-surface-area, porous metal-free substrates via nanoarchitectonic strategies could provide efficient ion-diffusion pathways and facilitate faster electron transfer during the electrochemical hydrogen evolution process. Herein, a g-C₃N₄–polypyrrole (Ppy) composite is decorated on a metal-organic framework (MOF)-derived carbon material to demonstrate an effective, precious-metal-free platform for hydrogen and oxygen evolution through the overall water splitting process. MOFs can be thermally converted into porous carbon, maintaining the morphology to offer high surface area, tunable porosity, and abundant active sites for electrocatalysis [21]. Again, the g-C₃N₄-Ppy heterostructure improves charge transport, increases the accessible active sites, and has been shown to enhance photocatalytic and electrocatalytic hydrogen production performance [22–23]. On the other hand, the Zn–MOF–derived carbon nanorod architecture serves as the robust and highly conducting base material for decorating g–C₃N₄–Ppy in the ternary nanocomposite (g-C₃N₄-Ppy/CR) to provide better HER and OER performance. The unique heterointerface of the electrocatalyst endows it with outstanding bifunctional activity, requiring overpotentials of only 355 mV and 187 mV to achieve 10 mA cm − 2 current density with a small Tafel slope of 86 mV dec − 1 and 105 mV dec − 1 for OER and HER, respectively. In overall water splitting, a cell voltage of 1.8 V was sufficient to achieve a current density of 10 mA cm − 2 , which is only 0.07 V higher than the commercially available RuO 2 -Pt/C catalysts. Notably, the standard overall water splitting over the g-C 3 N 4 -Ppy/CR catalyst exhibits significant electrochemical stability and comparable OER and HER kinetics to those of a commercial catalyst. Experimental 2.1 Materials and methods Trisodium citrate, urea, and trimesic acid (H₃BTC) were purchased from Avra Synthesis Pvt. Ltd., along with zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O), N, N -dimethylformamide (DMF), methanol (MeOH), and hydrochloric acid (HCl). Ethanol (EtOH), pyrrole, and 3-chloroperbenzoic acid were obtained from Sigma-Aldrich. All chemicals were used as received, without any additional purification. Distilled water was used throughout all synthesis and washing steps. Graphitic carbon nitride (g-C₃N₄) and g-C₃N₄–Ppy composite were synthesized according to our previous report [24]. For comparative purposes, pure polypyrrole (Ppy) nanospheres were synthesized under identical conditions, except that the g-C₃N₄ precursor was excluded from the reaction mixture. The ZnHKUST MOF and the MOF-derived porous carbon nanorod, CR, were obtained following a previously reported procedure [24–26]. The dried Zn-HKUST powder was subsequently subjected to pyrolysis at 1000°C for 1 hour under an argon atmosphere in a tubular furnace, with a controlled heating rate of 10°C/min⁻ 1 . Upon natural cooling to room temperature, the resulting product was collected and denoted CR. 2.2 Characterization Techniques Powder X-ray diffraction (PXRD) patterns were recorded using a Rigaku Ultima IV diffractometer equipped with Cu Kα radiation (λ = 1.5406 Å), operated at a scan rate of 0.01° min⁻¹. The surface morphology of the samples was examined using a FEI Apreo scanning electron microscope (SEM) operated at an accelerating voltage of 30 kV. X-ray photoelectron spectroscopy (XPS) measurements were performed on a Thermo Scientific Multilab 2000 spectrometer, equipped with Al Kα radiation (1486.6 eV), operating at 15 kV and 10 mA (150 W). The binding energy values were referenced to the C 1s peak at 284.85 eV. For XPS analysis, the samples were mounted on conductive carbon tape and pre-treated under an ultrahigh vacuum of 8.0 × 10⁻⁹ Torr for 5 h, followed by transfer to the analyser chamber at 5.0 × 10⁻⁹ Torr. Spectra were collected with a pass energy of 30 eV and a step size of 0.05 eV. Data processing, including smart background correction and peak deconvolution, was performed using Avantage software (version 5.9931) employing Gaussian–Lorentzian peak fitting with convergence set at 0.0001, a maximum of 100 iterations, and the Powell fitting algorithm. High-resolution transmission electron microscopy (HR-TEM) was performed on a FEI Tecnai G2 20 STEM instrument, operated at an acceleration voltage of 200 kV, to examine the fine structural features of the samples. Results and discussions Initially, g-C₃N₄ was synthesized through a hydrothermal route employing urea and trisodium citrate as precursor materials [24]. For the fabrication of the g-C₃N₄–Ppy/CR composite, the g-C₃N₄–Ppy intermediate was first prepared using 3-chloroperbenzoic acid as both an oxidizing and structure-directing agent in a mixed water–ethanol solvent system [24]. The use of the water–ethanol mixture effectively modulated the reaction kinetics and morphology of the resulting material. Notably, 3-chloroperbenzoic acid, with an oxidation potential of 0.68 V, possesses a higher oxidative strength than ethanol, thereby facilitating controlled polymerization and uniform composite formation. The CR was produced via controlled pyrolysis of the synthesized Zn-HKUST at 1000°C under an argon atmosphere [24–26]. During pyrolysis, the complete evaporation of Zn, whose boiling point is approximately 907°C, led to the formation of an amorphous carbon framework that retained the rod-like morphology of the parent MOF. Further details regarding the synthesis optimization and characterization of Zn-HKUST and CR can be found in our previous reports [24–26]. The morphological characteristics of the synthesized g-C₃N₄–Ppy/CR composite were investigated using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The TEM images (Fig. 1 a–b) provided insight into the composite morphology, where the dark base corresponded to the CR substrate, and the lighter protrusions were attributed to the g-C₃N₄–Ppy coating, confirming the formation of a unique prickly nanorod structure. The FESEM image of g-C₃N₄–Ppy (shown in Fig. S1 , SI) revealed the nanosphere-type morphology. Again, the FESEM image g-C₃N₄–Ppy/CR (Fig. 1 c) further confirmed the uniform growth of g-C₃N₄–Ppy nanospheres on the CR surface, resulting in nano-throne-like protrusions. After deposition, the self-assembled g-C₃N₄–Ppy nanostructures densely covered the CR, forming prickly, thorn-like architectures. Additionally, elemental mapping (Fig. 1 d–g) demonstrated the uniform distribution of all constituent elements across the g-C₃N₄–Ppy/CR composite, validating the successful synthesis of a homogeneous ternary structure. X-ray photoelectron spectroscopy (XPS) was employed to probe the surface composition and electronic states of the material. The XPS survey spectra ( Fig. S2 , SI) verified the presence of C, N, and O as the elements in g-C₃N₄–PPy/CR. As shown in Fig. 2 a, the fitted C 1s core level spectrum revealed three peaks at 284.7, 285.7, and 289.1 eV, corresponding to sp²-hybridized carbon (C–C/C = C), C = N, and C = O functional groups, respectively. The N 1s spectrum (Fig. 2 b) displayed a major peak at 400.1 eV assigned to protonated nitrogen (–N–H), along with additional peaks at 398.3 eV and 403.6 eV attributed to C = N and N–O groups, respectively. The oxygenated functionalities on the g-C₃N₄ edges likely served as nucleation sites during oxidative polymerization, facilitating the coordination of pyrrole monomers to neutralize positive charges. The structural properties of g-C₃N₄–Ppy/CR were investigated using powder X-ray diffraction (PXRD). As presented in Fig. 2 c, the diffraction pattern of g-C₃N₄–Ppy displayed a broad peak cantered at 25.68°, characteristic of the amorphous phase of polypyrrole polymers [27–28]. In contrast, g-C₃N₄–Ppy/CR exhibited a pronounced and broader peak at 26.75°, corresponding to the (002) plane of graphitic carbon, confirming an enhanced graphitic character following the integration of the polymer composite onto the carbon nanorod surface [24]. The defect structure and degree of graphitization were further assessed by Raman spectroscopy. As shown in Fig. 2 d, the Raman spectrum of g-C₃N₄–Ppy/CR displayed two distinct peaks at 1339 cm⁻¹ (D band) and 1591 cm⁻¹ (G band), typical of disordered and graphitic carbon domains. The intensity ratio (I D /I G ) was calculated to be 0.996, indicating a nearly balanced contribution of graphitic order and defect sites, a desirable feature for efficient electrocatalytic performance [29]. Electrochemical OER and HER performances : The electrocatalytic study of g-C 3 N 4 -Ppy/CR catalyst for OER was evaluated and compared with a commercial catalyst, RuO 2 , in a 1 M KOH electrolyte solution using a standard three-electrode system. The catalyst-deposited Ni foam was used as the working electrode, platinum and Ag/AgCl were used as the counter and reference electrodes, respectively. The anodic linear sweep voltammetry (ALSV) curve for g-C 3 N 4 -Ppy/CR catalyst exhibited significant oxygen evolution in alkaline media. As shown in Fig. 3 a, the ALSV curve of g-C 3 N 4 -Ppy/CR catalyst takes only 355 mV overpotential to achieve 10 mA cm − 2 current density, which is only 31 mV higher than that of the commercial RuO 2 catalyst (324 mV) in a similar condition. To investigate the catalytic contribution of other components, such as CR, we examined the ALSV curve of the g-C 3 N 4 -Ppy without CR deposition. The g-C 3 N 4 -Ppy-modified electrode revealed an overpotential of 390 mV, which was higher than g-C 3 N 4 -Ppy/CR. The significant OER kinetics of the catalysts were further evaluated using the obtained Tafel slope. The g-C 3 N 4 -Ppy/CR catalyst exhibited a low Tafel slope of 135 mV dec − 1 (Fig. 3 b), confirming the swift charge transfer from the electrocatalytic interface of g-C 3 N 4 -Ppy/CR. To further investigate the catalytic durability in continuous operation, a chronoamperometric study was conducted for more than 50 hours, as shown in Fig. 3 c. The study revealed the sustained consistency of the catalyst at higher current densities during OER performance. For better understanding, ALSV curves were evaluated (inset of Fig. 3 c) before and after the chronoamperometric stability study for OER. The LSV curves remained almost unchanged even after 50 hours of chronoamperometric performance, demonstrating the sustainability of the g-C 3 N 4 -Ppy/CR catalyst. The enhanced electrocatalytic OER performance of g-C 3 N 4 -Ppy/CR can be attributed to the interfacial synergistic interaction among the three main components. The g-C 3 N 4 provided a high density of nitrogen-rich active sites, particularly pyridinic nitrogen, which exhibited their key role for promoting O-O bond formation during the OER process [30–31]. Additionally, graphitic N sites enhance the electronic structure around adjacent carbon atoms, thereby improving OER performance [24,32]. The overall water splitting process comprises two half-cell reactions that occur at the anode and the cathode. As discussed, the oxygen evolution process is an anodic process, whereas the HER is a cathodic process. The process essentially involves the reduction of protons (H+) or water molecules on the surface of the catalyst to produce hydrogen. As shown in Fig. 3 d, the cathodic linear sweep voltammetry (CLSV) curve of g-C 3 N 4 -Ppy/CR catalyst exhibited an overpotential of only 187 mV for HER. Although it was higher than that of a commercial Pt/C catalyst, insight into the HER performance of g-C 3 N 4 -Ppy/CR catalyst demonstrated promising sustainability for hydrogen production. The g-C 3 N 4 -Ppy/CR catalyst revealed a low Tafel slope of 136 mV dec − 1 , which was lower than that of the g-C 3 N 4 -Ppy catalyst (165 mV dec − 1 ), as shown in Fig. 3 e. The low Tafel slope validated g-C 3 N 4 -Ppy/CR as an active catalyst, as it involves a small overpotential to reach higher current densities [33]. The chronoamperometric performance was further evaluated for more than 22 h, as shown in Fig. 3 f, revealing remarkable stability at a higher current density of -4.5 mA cm − 2 . The identical CLSV curves of the g-C 3 N 4 -Ppy/CR-modified electrode before and after the stability study, as shown in Fig. 3 f inset, confirmed the robust nature of the developed catalyst for HER. To evaluate the electrochemically active surface area (ECSA) and roughness factor (R f ), the cyclic voltammetry at non-Faradic range was taken with different scan rates for the designed catalysts, as shown in Fig. S3-S6 . Calculating the double-layer capacitance (C dl ) from the CV plots, the ECSA and R f were determined using the formulas C dl/ C s and ECSA/area, respectively. The ECSA and R f value were calculated to be 13 cm² and 20.31 for g-C3N4-Ppy/CR, as shown in Fig. 4 a. This high ECSA value of the g-C 3 N 4 -Ppy/CR catalyst is advantageous for the electrocatalytic HER process, as it has more active sites and a large electrochemically active surface area. Figure 4 b presents the bar diagram of potentials required for OER and HER of designed g-C 3 N 4 -Ppy/CR catalysts to achieve 10 mA cm − 2 current densities, along with the potential differences ( ΔE ) between OER and HER. The ΔE value is very important for overall water splitting in any designed catalyst. The figure revealed that the commercial catalyst has a lower ΔE value of 1.73 V (vs. RHE), followed by 1.8 V (vs. RHE) for g-C 3 N 4 -Ppy/CR, and 1.94 V (vs. RHE) for g-C 3 N 4 -Ppy. Figure 4 c represents the LSV curves of the designed catalysts for OER and HER, from which the potential difference is derived to estimate the kinetics of the catalysts. Since the g-C 3 N 4 -Ppy/CR catalyst exhibited excellent OER and HER performance in alkaline media, the alkaline overall water splitting was carried out by using a two-electrode system. As shown in Fig. 5 a, the g-C 3 N 4 -Ppy/CR||g-C 3 N 4 -Ppy/CR-based water electrolyser cell exhibited excellent overall water splitting performance in alkaline media. The current density of 10 mA cm − 2 can be achieved at a cell voltage of 1.8 V. The obtained cell voltage is only 0.07 V higher than that of commercial catalyst-modified RuO 2 ||Pt/C electrodes. Figure 5 b explored the cell voltage required for the higher current densities. The modified g-C 3 N 4 -Ppy/CR||g-C 3 N 4 -Ppy/CR cell required cell voltages of 1.8 V, 1.98 V, and 2.11 V to achieve current densities of 10, 20, and 30 mA cm − 2 , respectively. Moreover g-C 3 N 4 -Ppy/CR||g-C 3 N 4 -Ppy/CR electrode exhibited significant activity even after more than 20 hours of operation. Figure 5 c revealed that the g-C 3 N 4 -Ppy/CR||g-C 3 N 4 -Ppy/CR cell divulged excellent stability at a higher current density of 3.1 mA cm − 2 during continuous operation. The LSV curves (Fig. 5 d) showed that the g-C 3 N 4 -Ppy/CR||g-C 3 N 4 -Ppy/CR cell revealed no such potential changes after 20 hours of chronoamperometric performance. Figure 5 e represents the two-electrode system with a modified g-C 3 N 4 -Ppy/CR||g-C 3 N 4 -Ppy/CR electrode-based device for overall water splitting. According to the study, the designed catalyst exhibited a higher surface area and high porosity, facilitating the rapid diffusion of ions and oxygen species to the active sites. On the other hand, the intrinsic electrical conductivity enhances charge transfer kinetics across the catalyst interface. Conclusions In summary, we developed a g-C 3 N 4 -Ppy hybrid polymer composite, which was anchored on Zn-MOF-derived carbon nanorod to provide a ternary nanocomposite, g-C 3 N 4 -Ppy/CR, that exhibited high-performance water electrocatalysis. The matrix of g-C 3 N 4 -Ppy was synthesized under static conditions and anchored to the surface of the MOF-derived carbon nanorod, which was then characterized using structural and morphological characterization techniques. The catalyst was used to evaluate its bifunctional performance in terms of OER and HER. g-C 3 N 4 -Ppy/CR experienced a lower overpotential of 355 mV and 187 mV at 10 mA/cm 2 during OER and HER performance, respectively. The designed catalyst also provided excellent overall water splitting performance with high durability. This high-performance g-C 3 N 4 -PPy/CR catalyst provided a novel approach for architecting low-cost, metal-free, high-efficiency electrocatalysts for HER, OER, and overall water splitting. Declarations ASSOCIATED CONTENT Supporting Information Supporting information includes characterizations of materials, such as SEM images, XPS data, and electrochemical calculations. Further data that support the findings of this study are available upon request. ACKNOWLEDGMENTS The authors acknowledge the DST-PURSE (SR/PURSE/2020/20) (G) project funding by the Department of Science and Technology (DST), Govt. of India. The authors are grateful to the DST-FIST project funding of the Department of Chemistry, BITS Pilani, Hyderabad campus, for infrastructural support. Author contributions A.K.P and A.R carried out the research work, analysed the data and wrote the manuscript. A.B analysed the data and wrote the manuscript. S.G.P. reviewed the manuscript. C.C. conceptualized, supervised, acquired funding and reviewed the manuscript. Data Availability All the datasets generated and analysed during the current study are represent in the graph format. Further data will be available upon request. Declarations Consent to participate Not applicable Consent for publish Not applicable Ethical approval Not applicable. The authors declare that present work doesn’t include any human or animal research data or biological materials. Competing interests The authors declare no competing interests. Conflicts of interest There are no conflicts to declare. ORCID ID Anup Kumar Pradhan: 0000-0002-0470-2953 Dr. Chanchal Chakraborty: 0000-0002-4829-1367 REFERENCES Jianjun Shi, Yong Bao, Rongrong Ye, Ju Zhong, Lijing Zhou, Zhen Zhao, Wanli Kang, Saule B. Aidarova. Recent progress and perspective of electrocatalysts for the hydrogen evolution reaction." Catal. Sci. & Technology 2025;15, no. 7: 2104-2131. https://doi.org/10.1039/D4CY01449A A. Goyal, S. Louisia, P. Moerland, M. T. M. Koper. Cooperative effect of cations and catalyst structure in tuning alkaline hydrogen evolution on Pt electrodes. J. Am. Chem. Soc., 2024;146 (11):7305–7312. https://doi.org/10.1021/jacs.3c11866 Q. Fu, J. Han, X. Wang, P. Xu, T. Yao, J. Zhong, W. Zhong, S. Liu, T. Gao, Z. Zhang, L. Xu, B. Song, 2D Transition metal dichalcogenides: design, modulation, and challenges in electrocatalysis. Adv. Mater. 2020; 33(6): 1907818–1907841. https://doi.org/10.1002/adma.201907818 Z. Li, S. Xin, Y. Zhang, Z. Zhang, C. Li, C. Li, R. Bao, J. Yi, M. Xu, J. Wang. Boosting elementary steps kinetics towards energetic alkaline hydrogen evolution via dual sites on phase-separated Ni–Cu–Mn/hydroxide, Chem. Eng. J. 2023; 138540: 451–459. https://doi.org/10.1016/j.cej.2022.138540. L. Liu, Y. Liu, C. Liu. Enhancing the Understanding of hydrogen evolution and oxidation reactions on Pt(111through Ab initio simulation of electrode/electrolyte kinetics. J. Am. Chem. Soc. 2020; 142(11): 4985–4989. https://doi.org/10.1021/jacs.9b13694. Q. Qin, H. Jang, X. Jiang, L. Wang, X. Wang, M. G. Kim, S. Liu, X. Liu, J. Cho, Constructing interfacial oxygen vacancy and ruthenium lewis acid–base Pairs to Boost the Alkaline Hydrogen Evolution Reaction Kinetics, Angew. Chem. 2024; 136(3): 202317622–202317623. https://doi.org/10.1002/anie.202317622. Y. Zang, D. Q. Lu, K. Wang, B. Li, P. Peng, Y.-Q. Lan, S. Q. Zang. A pyrolysis-free Ni/Fe bimetallic electrocatalyst for overall water splitting. Nat. Commun. 2023; 14(1): 1792. https://doi.org/10.1038/s41467-023-37530-9. Z. Zhang, C. Feng, C. Liu, M. Zuo, L. Qin, X. Yan, Y. Xing, H. Li, R. Si, S. Zhou, J. Zeng. Electrochemical deposition as a universal route for fabricating single-atom catalysts. Nat. Commun. 2020; 11(1): 1215–1222. https://doi.org/10.1038/s41467-020-14917-6 X. Wang, Z. Wang, Y. Cao, X. Liu, L. Zhou, J. Shi, B. Guo, D. Li, R. Ye, Z. Zhao. A facile synthesis of hierarchical CoFe2O4 nanosheets for efficient oxygen evolution in neutral medium. J. Solid State Chem. 2024; 331: 124553–124560. https://doi.org/10.1016/j.jssc.2024.124553 Z. W. Seh, J. Kibsgaard, C. F. Dickens, I. Chorkendorff, J. K. Nørskov, T. F. Jaramillo. Combining theory and experiment in electrocatalysis: Insights into materials design Science 2017; 355(6321): 4998–5009. https://doi.org/10.1126/science.aad4998. A. J. Shih, M. C. O. Monteiro, F. Dattila, D. Pavesi, M. Philips, A. H. M. da Silva, R. E. Vos, K. Ojha, S. Park, O. van der Heijden, G. Marcandalli, A. Goyal, M. Villalba, X. Chen, G. T. K. K. Gunasooriya, I. McCrum, R. Mom, N. López, M. T. M. Koper. Water electrolysis. Nat. Rev. Methods Primers 2022; 2(1): 84–102. DOI: 10.1038/s43586-022-00164-0 É. Lèbre, M. Stringer, K. Svobodova, J. R. Owen, D. Kemp, C. Côte, A. Arratia-Solar, R. K. Valenta. The social and environmental complexities of extracting energy transition metals. Nat. Commun. 2020; 11(1): 1–8. https://doi.org/10.1038/s41467-020-18661-9. ] J. Zhang, Z. Zhao, Z. Xia, L. Dai. A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions, Nat. Nanotechnol. 2015; 10: 444–452. https://doi.org/10.1038/nnano.2015.48. https://doi.org/10.1038/nnano.2015.48. P. Chandrasekharan Meenu, S.P. Datta, S.A. Singh, S. Dinda, C. Chakraborty, S. Roy. Polyaniline supported g-C 3 N 4 quantum dots surpass benchmark Pt/C: Development of morphologically engineered g-C 3 N 4 catalysts towards “metal-free” methanol electro-oxidation. J. Power Sources 2020; 461: 228150. https://doi.org/10.1016/j.jpowsour.2020.228150. S. Challagulla, S. Payra, C. Chakraborty, S. Roy. Determination of band edges and their influences on photocatalytic reduction of nitrobenzene by bulk and exfoliated g-C 3 N 4 . Phys. Chem. Chem. Phys. 2019; 21: 3174–3183. https://doi.org/10.1039/C8CP06855K. C. Lu, D. Wang, J. Zhao, S. Han, W. Chen. A Continuous Carbon Nitride Polyhedron Assembly for High‐Performance Flexible Supercapacitors. Adv. Funct. Mater. 2017; 27: 1606219. https://doi.org/10.1002/adfm.201606219. Q. Liu, J. Zhang, Graphene Supported Co-g-C 3 N 4 as a Novel Metal–Macrocyclic Electrocatalyst for the Oxygen Reduction Reaction in Fuel Cells, Langmuir 2013; 29: 3821–3828. https://doi.org/10.1021/la400003h. R. Jiang, L. Li, T. Sheng, G. Hu, Y. Chen, L. Wang. Edge-Site Engineering of Atomically Dispersed Fe–N 4 by Selective C–N Bond Cleavage for Enhanced Oxygen Reduction Reaction Activities. J. Am. Chem. Soc. 2018; 140: 11594–11598. https://doi.org/10.1021/jacs.8b07294. S. Mametja, O. K. Mmelesi, J. S. Sefadi, X. Liu, J. Gorimbo. Recent progress on the utilization of polypyrrole (PPy)-based nanocomposites for electrochemical applications. J. Power Sources 2025; 659: 238404. https://doi.org/10.1016/j.jpowsour.2025.238404 H. An, R. Zhang, Z. Li, L. Zhou, M. Shao, M. Wei. Highly efficient metal-free electrocatalysts toward oxygen reduction derived from carbon nanotubes@polypyrrole core–shell hybrids. J. Mater. Chem. A 2016; 4: 18008–18014. https://doi.org/10.1039/C6TA08892A. Sohini Bhattacharyya, Chayanika Das, Tapas Kumar Maji. MOF derived carbon based nanocomposite materials as efficient electrocatalysts for oxygen reduction and oxygen and hydrogen evolution reactions. RSC advances (2018); 8(47): 26728-26754. https://doi.org/10.1039/C8RA05102J. S. Hu, L. Ma, H. Wang, L. Zhang, Y. Zhao, G. Wu. Properties and photocatalytic performance of polypyrrole and polythiophene modified gC 3 N 4 nanocomposites. RSC Advances 2015; 5 (40):31947-31953. https://doi.org/10.1039/C5RA02883C. A. A. Feidenhans’l, Y. N. Regmi, C. Wei, D. Xia, J. Kibsgaard, L. A. King. Precious metal free hydrogen evolution catalyst design and application. Chemical Reviews 2024; 124 (9): 5617-5667. https://doi.org/10.1021/acs.chemrev.3c00712. A. K. Pradhan, S. Halder, S. G. Palani, C. Chakraborty. Hierarchical graphitic carbon nitride-polypyrrole on metal-organic framework-derived carbon nanorod: Metal-Free electrocatalyst for solid-state flexible zinc-air batteries. Journal of Power Sources 2025; 659 : 238425. https://doi.org/10.1016/j.jpowsour.2025.238425. A.K. Pradhan, S. Halder, C. Chakraborty. “Less is more”: Carbon nanostructure-tailored low platinum containing electrocatalysts for improved zinc-air battery efficiency. J. Energy Storage 98 2024; 98: 113008. https://doi.org/10.1016/j.est.2024.113008. A. K. Pradhan, S. Halder, C. Chakraborty. Metal–organic framework derived synergistic carbon nanoarchitectures boost bifunctional electrocatalytic performances toward methanol oxidation and oxygen reduction in Pt-nanoparticles, Surf. Interfaces 2024; 44: 103816. https://doi.org/10.1016/j.surfin.2023.103816. H. An, R. Zhang, Z. Li, L. Zhou, M. Shao, M. Wei. Highly efficient metal-free electrocatalysts toward oxygen reduction derived from carbon nanotubes@polypyrrole core–shell hybrids. J. Mater. Chem. A 2016; 4: 18008–18014. https://doi.org/10.1039/C6TA08892A. Z. Liu, X. Zhang, S. Poyraz, S.P. Surwade, S.K. Manohar. Oxidative Template for Conducting Polymer Nanoclips. J. Am. Chem. Soc. 2010; 132: 13158–13159. https://doi.org/10.1021/ja105966c. J. Sanetuntikul, C. Chuaicham, Y.-W. Choi, S. Shanmugam. Investigation of hollow nitrogen-doped carbon spheres as non-precious Fe–N 4 based oxygen reduction catalysts. J. Mater. Chem. A 2015; 3: 15473–15481. https://doi.org/10.1039/C5TA02677F. A.K. Pradhan, S. Halder, C. Chakraborty, Pt-nanoparticles on ZnO/carbon quantum dots: a trifunctional nanocomposite with superior electrocatalytic activity boosting direct methanol fuel cells and zinc–air batteries, J. Mater. Chem. A 2025; 13: 243–256. https://doi.org/10.1039/D4TA05630B. S. Halder, A.K. Pradhan, P. Sivasakthi, P.K. Samanta, C. Chakraborty. Engineering S, N-doped carbon nanosheets derived from thiazolothiazole-based conjugated polymer for efficient electrocatalytic oxygen evolution and Zn-air battery. Mater. Today Chem . 2023; 32: 101649. https://doi.org/10.1016/j.mtchem.2023.101649. A. Torres-Pinto, A.M. Díez, C.G. Silva, J.L. Faria, M.A. ´ Sanroman, ´ A.M.T. Silva, M. Pazos. Tuning graphitic carbon nitride (g-C 3 N 4 electrocatalysts for efficient oxygen evolution reaction (OER). Fuel 2024; 360: 130575. https://doi.org/ 10.1016/j.fuel.2023.130575. P. G. Kedar, A. K. Pradhan, A. S. Jadhav, C. Chakraborty, S. T. Ingle. (2025). Graphene-based Ni/TiO 2 nanocomposite electrode material for sustainable hydrogen evolution reaction. Results in Surfaces and Interfaces 2025 19 , 100508. https://doi.org/10.1016/j.rsurfi.2025.100508. Additional Declarations No competing interests reported. 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1","display":"","copyAsset":false,"role":"figure","size":448264,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a-b)\u003c/strong\u003e TEM and \u003cstrong\u003e(c)\u003c/strong\u003e SEM images of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst. \u003cstrong\u003e(d-g)\u003c/strong\u003e Elemental mapping of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8005480/v1/5568644754df98e9e3503e04.png"},{"id":96830640,"identity":"25dce927-5ec0-4f5c-a359-88c8350d83db","added_by":"auto","created_at":"2025-11-26 13:47:39","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":207629,"visible":true,"origin":"","legend":"\u003cp\u003eCore level\u003cstrong\u003e \u003c/strong\u003eXPS spectra\u003cstrong\u003e (a) \u003c/strong\u003eC 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the ALSV curves before and after the chronoamperometric study given in the inset.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8005480/v1/9d75753dca81decac3215998.png"},{"id":96918899,"identity":"96c2978d-76de-4ba4-9155-822d4a09a752","added_by":"auto","created_at":"2025-11-27 14:12:49","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":181014,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a)\u003c/strong\u003e Bar diagram of ECSA and R\u003csub\u003ef\u003c/sub\u003e for g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst. \u003cstrong\u003e(b) \u003c/strong\u003eBar diagram of the obtained potentials from HER and OER performances of the catalysts. \u003cstrong\u003e(c) \u003c/strong\u003eLSV curves for the overall water splitting of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst with other controls.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8005480/v1/c6a0bfb543fe13ff3ed7645a.png"},{"id":96830649,"identity":"9f266cd5-49e8-4d3a-928b-f7dc14211f11","added_by":"auto","created_at":"2025-11-26 13:47:39","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":352003,"visible":true,"origin":"","legend":"\u003cp\u003eOverall water splitting performance by g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR in 1M KOH. \u003cstrong\u003e(a) \u003c/strong\u003eThe\u003cstrong\u003e \u003c/strong\u003eLSVs and \u003cstrong\u003e(b)\u003c/strong\u003e bar diagram of cell voltages required at different current densities by g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR and RuO\u003csub\u003e2\u003c/sub\u003e||Pt/C modified cells. \u003cstrong\u003e(c) \u003c/strong\u003eChronoamperometric study for overall water splitting by g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR.\u003cstrong\u003e (d) \u003c/strong\u003eLSV curve of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR cell before and after the chronoamperometry study. \u003cstrong\u003e(e) \u003c/strong\u003eImage of\u003cstrong\u003e \u003c/strong\u003ea two-electrode system device for overall water splitting.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8005480/v1/214e11569b9cab585296b28a.png"},{"id":96923220,"identity":"17402465-4602-4a5a-a012-019c213fb770","added_by":"auto","created_at":"2025-11-27 14:21:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1979243,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8005480/v1/63737779-86ce-455f-90a0-38b66f78d623.pdf"},{"id":96917995,"identity":"def6c40e-bdcf-4ed7-9c51-e0ae7e9dd311","added_by":"auto","created_at":"2025-11-27 14:10:57","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":1211682,"visible":true,"origin":"","legend":"","description":"","filename":"SupplymentaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-8005480/v1/c49998d5c76da7865f06c6b0.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Interfacial Synergetic Integration of Graphitic Carbon Nitride-Polypyrrole Anchored on Carbon Nanorod for Efficient Water Electrolysis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eOver the past decade, global energy demand has surged dramatically, primarily due to rapid population growth and accelerated industrialization [1\u0026ndash;3]. Currently, conventional fossil fuels, such as coal, oil, and natural gas, still account for more than 60% of the world\u0026rsquo;s total energy needs, whereas renewable sources, including solar, wind, tidal, and geothermal energy, contribute less than 40%. This heavy dependence on fossil fuels not only accelerates their depletion but also leads to critical environmental issues, including air pollution, global warming, and ecosystem degradation. Hence, the transition toward renewable and environmentally sustainable energy sources has become a pressing global necessity to ensure long-term energy security and ecological balance. Among the various clean energy carriers, hydrogen has garnered considerable attention as a next-generation fuel due to its high energy density, abundance, and zero-emission characteristics [4\u0026ndash;7]. Currently, most hydrogen is produced through methane steam reforming, a process that is limited by low energy efficiency and high carbon dioxide emissions. To overcome these drawbacks, alternative approaches such as thermal catalysis, photocatalysis, and electrocatalysis have been widely explored for sustainable hydrogen production through water splitting.\u003c/p\u003e\u003cp\u003eElectrocatalytic water splitting stands out as one of the most efficient and environmentally friendly routes for hydrogen generation. This technique utilizes electrical energy to decompose water into hydrogen and oxygen, and can be seamlessly integrated with renewable power sources such as wind and solar energy, thereby enhancing the overall efficiency of sustainable energy systems. The process involves two half-reactions: the oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction (HER) at the cathode. Since HER plays a decisive role in determining the efficiency and cost-effectiveness of hydrogen production, designing highly active, stable, and low-cost HER electrocatalysts has become a major research focus in the field of energy materials and electrochemistry [8\u0026ndash;12].\u003c/p\u003e\u003cp\u003eGraphitic carbon nitride (g-C₃N₄) is a layered compound composed of sp\u0026sup2;-hybridized carbon and nitrogen atoms arranged in a graphite-like framework. It has gained significant attention as a promising catalyst owing to its high nitrogen content, large surface area, and abundance of active sites [13\u0026ndash;16]. Its well-defined electronic structure, excellent thermal stability, and tunable active centers make it particularly effective for electrocatalysis [13\u0026ndash;14]. To overcome its limited electrical conductivity, researchers have sought to modify the electronic structure of g-C₃N₄ by tailoring metal\u0026ndash;nitrogen coordination sites (M\u0026ndash;N₄) [17\u0026ndash;18]. Furthermore, strategies such as elemental doping and heterojunction construction have been demonstrated to enhance charge transport and structural stability, thereby broadening the potential of g-C₃N₄ for high-performance catalytic applications [18].\u003c/p\u003e\u003cp\u003eNitrogen-rich, metal-free conducting polymers, such as polypyrrole and polyaniline, hold great promise for developing efficient metal-free electrocatalysts for the HER and OER through overall water splitting [19]. The formation of heterojunctions with these polymers can enhance their chemical stability, expose more active sites, and improve electrical conductivity, all of which are crucial for accelerating HER and OER kinetics [19]. Hongli An \u003cem\u003eet al.\u003c/em\u003e reported a core\u0026ndash;shell hybrid structure of polypyrrole and carbon nanotubes (CNTs), which exhibited superior charge transport and an increased number of catalytic sites, leading to enhanced electrocatalytic activity [20]. Furthermore, incorporating such heterostructures onto high-surface-area, porous metal-free substrates via nanoarchitectonic strategies could provide efficient ion-diffusion pathways and facilitate faster electron transfer during the electrochemical hydrogen evolution process.\u003c/p\u003e\u003cp\u003eHerein, a g-C₃N₄\u0026ndash;polypyrrole (Ppy) composite is decorated on a metal-organic framework (MOF)-derived carbon material to demonstrate an effective, precious-metal-free platform for hydrogen and oxygen evolution through the overall water splitting process. MOFs can be thermally converted into porous carbon, maintaining the morphology to offer high surface area, tunable porosity, and abundant active sites for electrocatalysis [21]. Again, the g-C₃N₄-Ppy heterostructure improves charge transport, increases the accessible active sites, and has been shown to enhance photocatalytic and electrocatalytic hydrogen production performance [22\u0026ndash;23]. On the other hand, the Zn\u0026ndash;MOF\u0026ndash;derived carbon nanorod architecture serves as the robust and highly conducting base material for decorating g\u0026ndash;C₃N₄\u0026ndash;Ppy in the ternary nanocomposite (g-C₃N₄-Ppy/CR) to provide better HER and OER performance. The unique heterointerface of the electrocatalyst endows it with outstanding bifunctional activity, requiring overpotentials of only 355 mV and 187 mV to achieve 10 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e current density with a small Tafel slope of 86 mV dec\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 105 mV dec\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for OER and HER, respectively. In overall water splitting, a cell voltage of 1.8 V was sufficient to achieve a current density of 10 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, which is only 0.07 V higher than the commercially available RuO\u003csub\u003e2\u003c/sub\u003e-Pt/C catalysts. Notably, the standard overall water splitting over the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst exhibits significant electrochemical stability and comparable OER and HER kinetics to those of a commercial catalyst.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Materials and methods\u003c/h2\u003e\u003cp\u003eTrisodium citrate, urea, and trimesic acid (H₃BTC) were purchased from Avra Synthesis Pvt. Ltd., along with zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O), \u003cem\u003eN, N\u003c/em\u003e-dimethylformamide (DMF), methanol (MeOH), and hydrochloric acid (HCl). Ethanol (EtOH), pyrrole, and 3-chloroperbenzoic acid were obtained from Sigma-Aldrich. All chemicals were used as received, without any additional purification. Distilled water was used throughout all synthesis and washing steps. Graphitic carbon nitride (g-C₃N₄) and g-C₃N₄–Ppy composite were synthesized according to our previous report [24]. For comparative purposes, pure polypyrrole (Ppy) nanospheres were synthesized under identical conditions, except that the g-C₃N₄ precursor was excluded from the reaction mixture. The ZnHKUST MOF and the MOF-derived porous carbon nanorod, CR, were obtained following a previously reported procedure [24–26]. The dried Zn-HKUST powder was subsequently subjected to pyrolysis at 1000°C for 1 hour under an argon atmosphere in a tubular furnace, with a controlled heating rate of 10°C/min⁻\u003csup\u003e1\u003c/sup\u003e. Upon natural cooling to room temperature, the resulting product was collected and denoted CR.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Characterization Techniques\u003c/h2\u003e\u003cp\u003ePowder X-ray diffraction (PXRD) patterns were recorded using a Rigaku Ultima IV diffractometer equipped with Cu Kα radiation (λ = 1.5406 Å), operated at a scan rate of 0.01° min⁻¹. The surface morphology of the samples was examined using a FEI Apreo scanning electron microscope (SEM) operated at an accelerating voltage of 30 kV. X-ray photoelectron spectroscopy (XPS) measurements were performed on a Thermo Scientific Multilab 2000 spectrometer, equipped with Al Kα radiation (1486.6 eV), operating at 15 kV and 10 mA (150 W). The binding energy values were referenced to the C 1s peak at 284.85 eV. For XPS analysis, the samples were mounted on conductive carbon tape and pre-treated under an ultrahigh vacuum of 8.0 × 10⁻⁹ Torr for 5 h, followed by transfer to the analyser chamber at 5.0 × 10⁻⁹ Torr. Spectra were collected with a pass energy of 30 eV and a step size of 0.05 eV. Data processing, including smart background correction and peak deconvolution, was performed using Avantage software (version 5.9931) employing Gaussian–Lorentzian peak fitting with convergence set at 0.0001, a maximum of 100 iterations, and the Powell fitting algorithm. High-resolution transmission electron microscopy (HR-TEM) was performed on a FEI Tecnai G2 20 STEM instrument, operated at an acceleration voltage of 200 kV, to examine the fine structural features of the samples.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Results and discussions","content":"\u003cp\u003eInitially, g-C₃N₄ was synthesized through a hydrothermal route employing \u003cem\u003eurea\u003c/em\u003e and \u003cem\u003etrisodium citrate\u003c/em\u003e as precursor materials [24]. For the fabrication of the g-C₃N₄–Ppy/CR composite, the g-C₃N₄–Ppy intermediate was first prepared using 3-chloroperbenzoic acid as both an oxidizing and structure-directing agent in a mixed water–ethanol solvent system [24]. The use of the water–ethanol mixture effectively modulated the reaction kinetics and morphology of the resulting material. Notably, 3-chloroperbenzoic acid, with an oxidation potential of 0.68 V, possesses a higher oxidative strength than ethanol, thereby facilitating controlled polymerization and uniform composite formation. The CR was produced via controlled pyrolysis of the synthesized Zn-HKUST at 1000°C under an argon atmosphere [24–26]. During pyrolysis, the complete evaporation of Zn, whose boiling point is approximately 907°C, led to the formation of an amorphous carbon framework that retained the rod-like morphology of the parent MOF. Further details regarding the synthesis optimization and characterization of Zn-HKUST and CR can be found in our previous reports [24–26].\u003c/p\u003e\u003cp\u003eThe morphological characteristics of the synthesized g-C₃N₄–Ppy/CR composite were investigated using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The TEM images (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea–b) provided insight into the composite morphology, where the dark base corresponded to the CR substrate, and the lighter protrusions were attributed to the g-C₃N₄–Ppy coating, confirming the formation of a unique prickly nanorod structure. The FESEM image of g-C₃N₄–Ppy (shown in \u003cb\u003eFig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/b\u003e, SI) revealed the nanosphere-type morphology. Again, the FESEM image g-C₃N₄–Ppy/CR (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec) further confirmed the uniform growth of g-C₃N₄–Ppy nanospheres on the CR surface, resulting in nano-throne-like protrusions. After deposition, the self-assembled g-C₃N₄–Ppy nanostructures densely covered the CR, forming prickly, thorn-like architectures. Additionally, elemental mapping (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed–g) demonstrated the uniform distribution of all constituent elements across the g-C₃N₄–Ppy/CR composite, validating the successful synthesis of a homogeneous ternary structure.\u003c/p\u003e\u003cp\u003eX-ray photoelectron spectroscopy (XPS) was employed to probe the surface composition and electronic states of the material. The XPS survey spectra (\u003cb\u003eFig. S2\u003c/b\u003e, SI) verified the presence of C, N, and O as the elements in g-C₃N₄–PPy/CR. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, the fitted C 1s core level spectrum revealed three peaks at 284.7, 285.7, and 289.1 eV, corresponding to sp²-hybridized carbon (C–C/C = C), C = N, and C = O functional groups, respectively. The N 1s spectrum (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb) displayed a major peak at 400.1 eV assigned to protonated nitrogen (–N–H), along with additional peaks at 398.3 eV and 403.6 eV attributed to C = N and N–O groups, respectively. The oxygenated functionalities on the g-C₃N₄ edges likely served as nucleation sites during oxidative polymerization, facilitating the coordination of pyrrole monomers to neutralize positive charges. The structural properties of g-C₃N₄–Ppy/CR were investigated using powder X-ray diffraction (PXRD). As presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, the diffraction pattern of g-C₃N₄–Ppy displayed a broad peak cantered at 25.68°, characteristic of the amorphous phase of polypyrrole polymers [27–28]. In contrast, g-C₃N₄–Ppy/CR exhibited a pronounced and broader peak at 26.75°, corresponding to the (002) plane of graphitic carbon, confirming an enhanced graphitic character following the integration of the polymer composite onto the carbon nanorod surface [24]. The defect structure and degree of graphitization were further assessed by Raman spectroscopy. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed, the Raman spectrum of g-C₃N₄–Ppy/CR displayed two distinct peaks at 1339 cm⁻¹ (D band) and 1591 cm⁻¹ (G band), typical of disordered and graphitic carbon domains. The intensity ratio (I\u003csub\u003eD\u003c/sub\u003e/I\u003csub\u003eG\u003c/sub\u003e) was calculated to be 0.996, indicating a nearly balanced contribution of graphitic order and defect sites, a desirable feature for efficient electrocatalytic performance [29].\u003c/p\u003e\u003cp\u003e\u003cb\u003eElectrochemical OER and HER performances\u003c/b\u003e:\u003c/p\u003e\u003cp\u003eThe electrocatalytic study of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst for OER was evaluated and compared with a commercial catalyst, RuO\u003csub\u003e2\u003c/sub\u003e, in a 1 M KOH electrolyte solution using a standard three-electrode system. The catalyst-deposited Ni foam was used as the working electrode, platinum and Ag/AgCl were used as the counter and reference electrodes, respectively. The anodic linear sweep voltammetry (ALSV) curve for g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst exhibited significant oxygen evolution in alkaline media. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, the ALSV curve of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst takes only 355 mV overpotential to achieve 10 mA cm\u003csup\u003e− 2\u003c/sup\u003e current density, which is only 31 mV higher than that of the commercial RuO\u003csub\u003e2\u003c/sub\u003e catalyst (324 mV) in a similar condition. To investigate the catalytic contribution of other components, such as CR, we examined the ALSV curve of the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy without CR deposition. The g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy-modified electrode revealed an overpotential of 390 mV, which was higher than g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR. The significant OER kinetics of the catalysts were further evaluated using the obtained Tafel slope. The g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst exhibited a low Tafel slope of 135 mV dec\u003csup\u003e− 1\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb), confirming the swift charge transfer from the electrocatalytic interface of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR. To further investigate the catalytic durability in continuous operation, a chronoamperometric study was conducted for more than 50 hours, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec. The study revealed the sustained consistency of the catalyst at higher current densities during OER performance. For better understanding, ALSV curves were evaluated (inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec) before and after the chronoamperometric stability study for OER. The LSV curves remained almost unchanged even after 50 hours of chronoamperometric performance, demonstrating the sustainability of the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst. The enhanced electrocatalytic OER performance of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR can be attributed to the interfacial synergistic interaction among the three main components. The g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e provided a high density of nitrogen-rich active sites, particularly pyridinic nitrogen, which exhibited their key role for promoting O-O bond formation during the OER process [30–31]. Additionally, graphitic N sites enhance the electronic structure around adjacent carbon atoms, thereby improving OER performance [24,32].\u003c/p\u003e\u003cp\u003eThe overall water splitting process comprises two half-cell reactions that occur at the anode and the cathode. As discussed, the oxygen evolution process is an anodic process, whereas the HER is a cathodic process. The process essentially involves the reduction of protons (H+) or water molecules on the surface of the catalyst to produce hydrogen. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, the cathodic linear sweep voltammetry (CLSV) curve of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst exhibited an overpotential of only 187 mV for HER. Although it was higher than that of a commercial Pt/C catalyst, insight into the HER performance of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst demonstrated promising sustainability for hydrogen production. The g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst revealed a low Tafel slope of 136 mV dec\u003csup\u003e− 1\u003c/sup\u003e, which was lower than that of the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy catalyst (165 mV dec\u003csup\u003e− 1\u003c/sup\u003e), as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee. The low Tafel slope validated g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR as an active catalyst, as it involves a small overpotential to reach higher current densities [33]. The chronoamperometric performance was further evaluated for more than 22 h, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef, revealing remarkable stability at a higher current density of -4.5 mA cm\u003csup\u003e− 2\u003c/sup\u003e. The identical CLSV curves of the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR-modified electrode before and after the stability study, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef inset, confirmed the robust nature of the developed catalyst for HER.\u003c/p\u003e\u003cp\u003eTo evaluate the electrochemically active surface area (ECSA) and roughness factor (R\u003csub\u003ef\u003c/sub\u003e), the cyclic voltammetry at non-Faradic range was taken with different scan rates for the designed catalysts, as shown in \u003cb\u003eFig. S3-S6\u003c/b\u003e. Calculating the double-layer capacitance (C\u003csub\u003edl\u003c/sub\u003e) from the CV plots, the ECSA and R\u003csub\u003ef\u003c/sub\u003e were determined using the formulas C\u003csub\u003edl/\u003c/sub\u003eC\u003csub\u003es\u003c/sub\u003e and ECSA/area, respectively. The ECSA and R\u003csub\u003ef\u003c/sub\u003e value were calculated to be 13 cm² and 20.31 for g-C3N4-Ppy/CR, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea. This high ECSA value of the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst is advantageous for the electrocatalytic HER process, as it has more active sites and a large electrochemically active surface area. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb presents the bar diagram of potentials required for OER and HER of designed g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalysts to achieve 10 mA cm\u003csup\u003e− 2\u003c/sup\u003e current densities, along with the potential differences (\u003cem\u003eΔE\u003c/em\u003e) between OER and HER. The \u003cem\u003eΔE\u003c/em\u003e value is very important for overall water splitting in any designed catalyst. The figure revealed that the commercial catalyst has a lower ΔE value of 1.73 V (vs. RHE), followed by 1.8 V (vs. RHE) for g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR, and 1.94 V (vs. RHE) for g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec represents the LSV curves of the designed catalysts for OER and HER, from which the potential difference is derived to estimate the kinetics of the catalysts.\u003c/p\u003e\u003cp\u003eSince the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR catalyst exhibited excellent OER and HER performance in alkaline media, the alkaline overall water splitting was carried out by using a two-electrode system. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR-based water electrolyser cell exhibited excellent overall water splitting performance in alkaline media. The current density of 10 mA cm\u003csup\u003e− 2\u003c/sup\u003e can be achieved at a cell voltage of 1.8 V. The obtained cell voltage is only 0.07 V higher than that of commercial catalyst-modified RuO\u003csub\u003e2\u003c/sub\u003e||Pt/C electrodes. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb explored the cell voltage required for the higher current densities. The modified g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR cell required cell voltages of 1.8 V, 1.98 V, and 2.11 V to achieve current densities of 10, 20, and 30 mA cm\u003csup\u003e− 2\u003c/sup\u003e, respectively.\u003c/p\u003e\u003cp\u003eMoreover g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR electrode exhibited significant activity even after more than 20 hours of operation. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec revealed that the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR cell divulged excellent stability at a higher current density of 3.1 mA cm\u003csup\u003e− 2\u003c/sup\u003e during continuous operation. The LSV curves (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed) showed that the g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR cell revealed no such potential changes after 20 hours of chronoamperometric performance. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ee represents the two-electrode system with a modified g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR||g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR electrode-based device for overall water splitting. According to the study, the designed catalyst exhibited a higher surface area and high porosity, facilitating the rapid diffusion of ions and oxygen species to the active sites. On the other hand, the intrinsic electrical conductivity enhances charge transfer kinetics across the catalyst interface.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, we developed a g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy hybrid polymer composite, which was anchored on Zn-MOF-derived carbon nanorod to provide a ternary nanocomposite, g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR, that exhibited high-performance water electrocatalysis. The matrix of g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy was synthesized under static conditions and anchored to the surface of the MOF-derived carbon nanorod, which was then characterized using structural and morphological characterization techniques. The catalyst was used to evaluate its bifunctional performance in terms of OER and HER. g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR experienced a lower overpotential of 355 mV and 187 mV at 10 mA/cm\u003csup\u003e2\u003c/sup\u003e during OER and HER performance, respectively. The designed catalyst also provided excellent overall water splitting performance with high durability. This high-performance g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-PPy/CR catalyst provided a novel approach for architecting low-cost, metal-free, high-efficiency electrocatalysts for HER, OER, and overall water splitting.\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eASSOCIATED CONTENT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSupporting Information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSupporting information includes characterizations of materials, such as SEM images, XPS data, and electrochemical calculations. Further data that support the findings of this study are available\u0026nbsp;upon request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eACKNOWLEDGMENTS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors acknowledge the DST-PURSE (SR/PURSE/2020/20) (G) project funding by the Department of Science and Technology (DST), Govt. of India. The authors are grateful to the DST-FIST project funding of the Department of Chemistry, BITS Pilani, Hyderabad campus, for infrastructural support.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA.K.P and A.R carried out the research work, analysed the data and wrote the manuscript. A.B analysed the data and wrote the manuscript. S.G.P. reviewed the manuscript. C.C. conceptualized, supervised, acquired funding and reviewed the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll the\u0026nbsp;datasets generated and analysed during the current study are represent in the graph format.\u0026nbsp;Further data will be available upon request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publish\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. The authors declare that present work doesn’t include any human or animal research data or biological materials.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere are no conflicts to declare.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eORCID ID\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnup Kumar Pradhan: 0000-0002-0470-2953\u003c/p\u003e\n\u003cp\u003eDr. Chanchal Chakraborty: 0000-0002-4829-1367\u003c/p\u003e"},{"header":"REFERENCES ","content":"\u003col\u003e\n\u003cli\u003eJianjun Shi, Yong Bao, Rongrong Ye, Ju Zhong, Lijing Zhou, Zhen Zhao, Wanli Kang, Saule B. Aidarova. Recent progress and perspective of electrocatalysts for the hydrogen evolution reaction.\u0026quot; \u003cem\u003eCatal. Sci. \u0026amp; Technology\u003c/em\u003e 2025;15, no. 7: 2104-2131. https://doi.org/10.1039/D4CY01449A\u003c/li\u003e\n\u003cli\u003eA. Goyal, S. Louisia, P. Moerland, M. T. M. Koper. Cooperative effect of cations and catalyst structure in tuning alkaline hydrogen evolution on Pt electrodes. J. Am. Chem. Soc., 2024;146 (11):7305\u0026ndash;7312. https://doi.org/10.1021/jacs.3c11866\u003c/li\u003e\n\u003cli\u003eQ. Fu, J. Han, X. Wang, P. Xu, T. Yao, J. Zhong, W. Zhong, S. Liu, T. Gao, Z. Zhang, L. Xu, B. Song, 2D Transition metal dichalcogenides: design, modulation, and challenges in electrocatalysis. Adv. Mater. 2020; 33(6): 1907818\u0026ndash;1907841. https://doi.org/10.1002/adma.201907818\u003c/li\u003e\n\u003cli\u003eZ. Li, S. Xin, Y. Zhang, Z. Zhang, C. Li, C. Li, R. Bao, J. Yi, M. Xu, J. Wang. Boosting elementary steps kinetics towards energetic alkaline hydrogen evolution via dual sites on phase-separated Ni\u0026ndash;Cu\u0026ndash;Mn/hydroxide, Chem. Eng. J. 2023; 138540: 451\u0026ndash;459. https://doi.org/10.1016/j.cej.2022.138540.\u003c/li\u003e\n\u003cli\u003eL. Liu, Y. Liu, C. Liu. Enhancing the Understanding of hydrogen evolution and oxidation reactions on Pt(111through Ab initio simulation of electrode/electrolyte kinetics. J. Am. Chem. Soc. 2020; 142(11): 4985\u0026ndash;4989. https://doi.org/10.1021/jacs.9b13694.\u003c/li\u003e\n\u003cli\u003eQ. Qin, H. Jang, X. Jiang, L. Wang, X. Wang, M. G. Kim, S. Liu, X. Liu, J. Cho, Constructing interfacial oxygen vacancy and ruthenium lewis acid\u0026ndash;base Pairs to Boost the Alkaline Hydrogen Evolution Reaction Kinetics, Angew. Chem. 2024; 136(3): 202317622\u0026ndash;202317623. https://doi.org/10.1002/anie.202317622.\u003c/li\u003e\n\u003cli\u003eY. Zang, D. Q. Lu, K. Wang, B. Li, P. Peng, Y.-Q. Lan, S. Q. Zang. A pyrolysis-free Ni/Fe bimetallic electrocatalyst for overall water splitting. Nat. Commun. 2023; 14(1): 1792. https://doi.org/10.1038/s41467-023-37530-9.\u003c/li\u003e\n\u003cli\u003eZ. Zhang, C. Feng, C. Liu, M. Zuo, L. Qin, X. Yan, Y. Xing, H. Li, R. Si, S. Zhou, J. Zeng. Electrochemical deposition as a universal route for fabricating single-atom catalysts. Nat. Commun. 2020; 11(1): 1215\u0026ndash;1222. https://doi.org/10.1038/s41467-020-14917-6\u003c/li\u003e\n\u003cli\u003eX. Wang, Z. Wang, Y. Cao, X. Liu, L. Zhou, J. Shi, B. Guo, D. Li, R. Ye, Z. Zhao. A facile synthesis of hierarchical CoFe2O4 nanosheets for efficient oxygen evolution in neutral medium. J. Solid State Chem. 2024; 331: 124553\u0026ndash;124560. https://doi.org/10.1016/j.jssc.2024.124553\u003c/li\u003e\n\u003cli\u003eZ. W. Seh, J. Kibsgaard, C. F. Dickens, I. Chorkendorff, J. K. N\u0026oslash;rskov, T. F. Jaramillo. Combining theory and experiment in electrocatalysis: Insights into materials design Science 2017; 355(6321): 4998\u0026ndash;5009. https://doi.org/10.1126/science.aad4998.\u003c/li\u003e\n\u003cli\u003eA. J. Shih, M. C. O. Monteiro, F. Dattila, D. Pavesi, M. Philips, A. H. M. da Silva, R. E. Vos, K. Ojha, S. Park, O. van der Heijden, G. Marcandalli, A. Goyal, M. Villalba, X. Chen, G. T. K. K. Gunasooriya, I. McCrum, R. Mom, N. L\u0026oacute;pez, M. T. M. Koper. Water electrolysis. Nat. Rev. Methods Primers 2022; 2(1): 84\u0026ndash;102.\u003cstrong\u003eDOI:\u003c/strong\u003e 10.1038/s43586-022-00164-0\u003c/li\u003e\n\u003cli\u003e\u0026Eacute;. L\u0026egrave;bre, M. Stringer, K. Svobodova, J. R. Owen, D. Kemp, C. C\u0026ocirc;te, A. Arratia-Solar, R. K. Valenta. The social and environmental complexities of extracting energy transition metals. Nat. Commun. 2020; 11(1): 1\u0026ndash;8. https://doi.org/10.1038/s41467-020-18661-9.\u003c/li\u003e\n\u003cli\u003e] J. Zhang, Z. Zhao, Z. Xia, L. Dai. A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions, Nat. Nanotechnol. 2015; 10: 444\u0026ndash;452. https://doi.org/10.1038/nnano.2015.48. https://doi.org/10.1038/nnano.2015.48.\u003c/li\u003e\n\u003cli\u003eP. Chandrasekharan Meenu, S.P. Datta, S.A. Singh, S. Dinda, C. Chakraborty, S. Roy. Polyaniline supported g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e quantum dots surpass benchmark Pt/C: Development of morphologically engineered g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e catalysts towards \u0026ldquo;metal-free\u0026rdquo; methanol electro-oxidation. J. Power Sources 2020; 461: 228150. https://doi.org/10.1016/j.jpowsour.2020.228150.\u003c/li\u003e\n\u003cli\u003eS. Challagulla, S. Payra, C. Chakraborty, S. Roy. Determination of band edges and their influences on photocatalytic reduction of nitrobenzene by bulk and exfoliated g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e. Phys. Chem. Chem. Phys. 2019; 21: 3174\u0026ndash;3183. https://doi.org/10.1039/C8CP06855K.\u003c/li\u003e\n\u003cli\u003eC. Lu, D. Wang, J. Zhao, S. Han, W. Chen. A Continuous Carbon Nitride Polyhedron Assembly for High‐Performance Flexible Supercapacitors. Adv. Funct. Mater. 2017; 27: 1606219. https://doi.org/10.1002/adfm.201606219.\u003c/li\u003e\n\u003cli\u003eQ. Liu, J. Zhang, Graphene Supported Co-g-C\u003csub\u003e3\u003c/sub\u003e N\u003csub\u003e4\u003c/sub\u003e as a Novel Metal\u0026ndash;Macrocyclic Electrocatalyst for the Oxygen Reduction Reaction in Fuel Cells, Langmuir 2013; 29: 3821\u0026ndash;3828. https://doi.org/10.1021/la400003h.\u003c/li\u003e\n\u003cli\u003eR. Jiang, L. Li, T. Sheng, G. Hu, Y. Chen, L. Wang. Edge-Site Engineering of Atomically Dispersed Fe\u0026ndash;N\u003csub\u003e4\u003c/sub\u003e by Selective C\u0026ndash;N Bond Cleavage for Enhanced Oxygen Reduction Reaction Activities. J. Am. Chem. Soc. 2018; 140: 11594\u0026ndash;11598. https://doi.org/10.1021/jacs.8b07294.\u003c/li\u003e\n\u003cli\u003eS. Mametja, O. K. Mmelesi, J. S. Sefadi, X. Liu, J. Gorimbo. Recent progress on the utilization of polypyrrole (PPy)-based nanocomposites for electrochemical applications. J. Power Sources 2025; 659: 238404. https://doi.org/10.1016/j.jpowsour.2025.238404 \u003c/li\u003e\n\u003cli\u003eH. An, R. Zhang, Z. Li, L. Zhou, M. Shao, M. Wei. Highly efficient metal-free electrocatalysts toward oxygen reduction derived from carbon nanotubes@polypyrrole core\u0026ndash;shell hybrids. J. Mater. Chem. A 2016; 4: 18008\u0026ndash;18014. https://doi.org/10.1039/C6TA08892A.\u003c/li\u003e\n\u003cli\u003eSohini Bhattacharyya, Chayanika Das, Tapas Kumar Maji. MOF derived carbon based nanocomposite materials as efficient electrocatalysts for oxygen reduction and oxygen and hydrogen evolution reactions. RSC advances (2018); 8(47): 26728-26754. https://doi.org/10.1039/C8RA05102J.\u003c/li\u003e\n\u003cli\u003eS. Hu, L. Ma, H. Wang, L. Zhang, Y. Zhao, G. Wu. Properties and photocatalytic performance of polypyrrole and polythiophene modified gC\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e nanocomposites. RSC Advances 2015; \u003cem\u003e5\u003c/em\u003e(40):31947-31953. https://doi.org/10.1039/C5RA02883C.\u003c/li\u003e\n\u003cli\u003eA. A. Feidenhans\u0026rsquo;l, Y. N. Regmi, C. Wei, D. Xia, J. Kibsgaard, L. A. King. Precious metal free hydrogen evolution catalyst design and application. Chemical Reviews 2024; \u003cem\u003e124\u003c/em\u003e(9): 5617-5667. https://doi.org/10.1021/acs.chemrev.3c00712.\u003c/li\u003e\n\u003cli\u003eA. K. Pradhan, S. Halder, S. G. Palani, C. Chakraborty. Hierarchical graphitic carbon nitride-polypyrrole on metal-organic framework-derived carbon nanorod: Metal-Free electrocatalyst for solid-state flexible zinc-air batteries. Journal of Power Sources 2025; \u003cem\u003e659\u003c/em\u003e: 238425. https://doi.org/10.1016/j.jpowsour.2025.238425.\u003c/li\u003e\n\u003cli\u003eA.K. Pradhan, S. Halder, C. Chakraborty. \u0026ldquo;Less is more\u0026rdquo;: Carbon nanostructure-tailored low platinum containing electrocatalysts for improved zinc-air battery efficiency. J. Energy Storage 98 2024; 98: 113008. https://doi.org/10.1016/j.est.2024.113008.\u003c/li\u003e\n\u003cli\u003eA. K. Pradhan, S. Halder, C. Chakraborty. Metal\u0026ndash;organic framework derived synergistic carbon nanoarchitectures boost bifunctional electrocatalytic performances toward methanol oxidation and oxygen reduction in Pt-nanoparticles, Surf. Interfaces 2024; 44: 103816. https://doi.org/10.1016/j.surfin.2023.103816.\u003c/li\u003e\n\u003cli\u003eH. An, R. Zhang, Z. Li, L. Zhou, M. Shao, M. Wei. Highly efficient metal-free electrocatalysts toward oxygen reduction derived from carbon nanotubes@polypyrrole core\u0026ndash;shell hybrids. J. Mater. Chem. A 2016; 4: 18008\u0026ndash;18014. https://doi.org/10.1039/C6TA08892A.\u003c/li\u003e\n\u003cli\u003eZ. Liu, X. Zhang, S. Poyraz, S.P. Surwade, S.K. Manohar. Oxidative Template for Conducting Polymer Nanoclips. J. Am. Chem. Soc. 2010; 132: 13158\u0026ndash;13159. https://doi.org/10.1021/ja105966c.\u003c/li\u003e\n\u003cli\u003eJ. Sanetuntikul, C. Chuaicham, Y.-W. Choi, S. Shanmugam. Investigation of hollow nitrogen-doped carbon spheres as non-precious Fe\u0026ndash;N\u003csub\u003e4\u003c/sub\u003e based oxygen reduction catalysts. J. Mater. Chem. A 2015; 3: 15473\u0026ndash;15481. https://doi.org/10.1039/C5TA02677F.\u003c/li\u003e\n\u003cli\u003eA.K. Pradhan, S. Halder, C. Chakraborty, Pt-nanoparticles on ZnO/carbon quantum dots: a trifunctional nanocomposite with superior electrocatalytic activity boosting direct methanol fuel cells and zinc\u0026ndash;air batteries, J. Mater. Chem. A 2025; 13: 243\u0026ndash;256. https://doi.org/10.1039/D4TA05630B.\u003c/li\u003e\n\u003cli\u003eS. Halder, A.K. Pradhan, P. Sivasakthi, P.K. Samanta, C. Chakraborty. Engineering S, N-doped carbon nanosheets derived from thiazolothiazole-based conjugated polymer for efficient electrocatalytic oxygen evolution and Zn-air battery. Mater. Today Chem\u003cem\u003e.\u003c/em\u003e 2023; 32: 101649. https://doi.org/10.1016/j.mtchem.2023.101649.\u003c/li\u003e\n\u003cli\u003eA. Torres-Pinto, A.M. D\u0026iacute;ez, C.G. Silva, J.L. Faria, M.A. \u0026acute; Sanroman, \u0026acute; A.M.T. Silva, M. Pazos. Tuning graphitic carbon nitride (g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003eelectrocatalysts for efficient oxygen evolution reaction (OER). Fuel 2024; 360: 130575. https://doi.org/ 10.1016/j.fuel.2023.130575.\u003c/li\u003e\n\u003cli\u003eP. G. Kedar, A. K. Pradhan, A. S. Jadhav, C. Chakraborty, S. T. Ingle. (2025). Graphene-based Ni/TiO\u003csub\u003e2\u003c/sub\u003e nanocomposite electrode material for sustainable hydrogen evolution reaction. \u003cem\u003eResults in Surfaces and Interfaces\u003c/em\u003e 2025 \u003cem\u003e19\u003c/em\u003e, 100508. https://doi.org/10.1016/j.rsurfi.2025.100508.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-electrochemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Electrochemistry](https://link.springer.com/journal/44373)","snPcode":"44373","submissionUrl":"https://submission.nature.com/new-submission/44373/3","title":"Discover Electrochemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Metal-free electrocatalyst, Hydrogen evolution reaction (HER), Oxygen evolution reaction (OER), Polypyrrole, Graphitic carbon nitride, Water electrolysis","lastPublishedDoi":"10.21203/rs.3.rs-8005480/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8005480/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHydrogen generation from electrolysis of water is one of the most sustainable strategies for clean energy conversion. However, the sluggish kinetics of oxygen and hydrogen evolution limit its practical implementation. Developing an efficient, low-cost, and durable bifunctional electrocatalyst for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is always in demand for promoting clean energy from water. In this work, we report a unique metal-free electrocatalyst composed of graphitic carbon nitride-polypyrrole on carbon nanorods (g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR) for efficient water electrocatalysis. The above electrocatalyst was synthesized by depositing g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy on the surface of a metal-organic framework-derived carbon nanorod (CR). The unique heterointerface of the electrocatalyst endows it with outstanding bifunctional activity, requiring overpotentials of only 355 mV and 187 mV to achieve 10 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e current density with a small Tafel slope of 86 mV dec\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 105 mV dec\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for OER and HER, respectively. The chronoamperometric performance further confirmed the long-term stability of the electrocatalyst, with over 50 hours of continuous operation maintained. Moreover, owing to the excellent OER and HER performance in alkaline media, the overall water splitting was carried out by using a two-electrode system. A cell voltage of 1.8 V was sufficient to achieve a current density of 10 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, which is only 0.07 V higher than the commercially available catalyst-modified cell. The g-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-Ppy/CR-modified cell also has excellent stability at a higher current density of 3.1 mA cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. These results highlight the synergistic interplay between the components and provide a promising strategy for designing new ternary electrocatalysts toward efficient overall water splitting and renewable hydrogen production.\u003c/p\u003e","manuscriptTitle":"Interfacial Synergetic Integration of Graphitic Carbon Nitride-Polypyrrole Anchored on Carbon Nanorod for Efficient Water Electrolysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-26 13:47:34","doi":"10.21203/rs.3.rs-8005480/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-12T12:32:07+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-10T16:11:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"248043467012204769799061836568736434908","date":"2025-12-09T04:24:42+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-29T03:49:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"19722596867120205235549862852430367069","date":"2025-11-19T06:34:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"39392630986085540400769029674217626154","date":"2025-11-17T14:44:20+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-17T04:06:28+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-16T18:09:45+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-11-15T17:49:09+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-11-14T06:00:42+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Electrochemistry","date":"2025-11-14T05:57:37+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-electrochemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Electrochemistry](https://link.springer.com/journal/44373)","snPcode":"44373","submissionUrl":"https://submission.nature.com/new-submission/44373/3","title":"Discover Electrochemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3eaf60cb-884f-476f-8ce0-67483fcdd384","owner":[],"postedDate":"November 26th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-01-28T10:26:10+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-26 13:47:34","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8005480","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8005480","identity":"rs-8005480","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}