First Principles Study of Photocatalytic Water Splitting by M1M2CO2 (M1=Zr,Hf; M2=Hf, Ti, Sc) MXenes

Using density functional theory (DFT), we investigated the structural, electronic, and optical properties of functionalized and doped MXenes such as M1M2CO2 (M1=Zr, Hf; M2=Hf, Ti, Sc). This study aimed to find a suitable photocatalyst that would work well in the water-splitting process. Among the calculated nanostructures, MXenes ZrHfCO2 and ZrTiCO2 were chosen as suitable photocatalysts for the water-splitting process. The calculated value of the band gaps with the GGA-PBE functional was 1.08(0.79) eV for the ZrHfCO2 (ZrTiCO2) monolayer. Also, the band gaps for these monolayers with the HSE06 hybrid functional were 1.86 and 1.57 eV, respectively. These MXenes' optical properties, such as complex dielectric function, refractive index, extinction coefficient, and reflectivity, were also investigated. The results showed that these monolayers had good absorption in the visible region. Additionally, we discovered that ZrHfCO2 and ZrTiCO2 MXenes could be used for the water-splitting process by calculating the photocatalytic properties. Meanwhile, the results indicate that the monolayers of ZrHfCO2 and ZrTiCO2 are ideal and promising materials for application in visible-light-driven photocatalysis.