Supercapacitive Performance of Sustainable/Eco-friendly Oxygen rich Activated-carbons derived using Hazardous Soot Particles

The present work aims the application of extremely hazardous and life-threatening soot particles released to environment from different industrial processes. These soot materials are proposed as potential source of functionalized nano carbons for energy storage application. In this work, soot samples were collected from various sources namely automobile emission, agricultural/forest waste and industrial works; and were chemically activated using KOH to obtain heteroatom functionalized activated carbons (i.e. activated coal soot (ACS), activated diesel soot (ADS) and activated wood soot (AWS) respectively) exhibiting large BET surface area (~ 846 m 2 g − 1 ). Morphological investigations (FESEM and HRTEM) reveals formation of interconnected granular aggregates exhibiting enormous inter-particle meso/microporous channels significant for electrolyte passage and lowering charge-transfer resistance. Structural characterizations (XRD, FTIR and Raman spectra) justify these soots having activated graphitic structures enriched with oxygen-based functionalities (e.g. -COOH, -OH, C 6 H 5 OH etc.) that impart hydrophilic character and excellent pseudocapacitive properties. Electrochemical measurements in 1 M H 2 SO 4 affirm high capacitance values (361–440 F g − 1 at 5 mV s − 1 ) for soot-based electrodes bestowed by high surface area in addition to meso/microporous structure. Nevertheless, AWS║AWS cell demonstrates remarkable stability over 5000 cycles at 50 mV s − 1 owing to high carbon enriched moiety relative to ADS║ADS and ACS║ACS supercapacitors which further illustrate greater activation of electrode materials during charge/discharge caused by high content of pseudocapacitive functionalities. Variations in electrochemistry can be attributed to structural organizations of the activated soot particles and variable percentage of heteroatoms in their carbon lattices which govern overall ‘ EDL plus pseudo ’ performances.