Two-dimensional TiC₂, ZrC₂ and VC₂: theoretical study and further improvement of doping atoms for electrocatalysis of water splitting

Abstract Through density functional theory (DFT) computations, the electronic attributes and electrocatalytic performance of monolayer TiC 2 , ZrC 2 , and VC 2 were explored for overall water splitting. It was found that their excellent stability and high electronic conductivity enable efficient charge transfer during catalytic reactions. Specifically, TiC 2 and ZrC 2 monolayers possess superior hydrogen evolution reaction (HER) reactivity under low H-coverage. Furthermore, doping these materials with Nb and Ta significantly improves HER performance under 100% hydrogencoverage, with the associated catalytic mechanisms thoroughly analyzed. The TiC 2 and VC 2 monolayers demonstrate exceptional bifunctional electrocatalytic reactivity for both HER (with Gibbs free energy of 0.08 eV and 0.17 eV, separately) and ORR (with overpotentials of 0.68 V and 0.58 V, respectively). Notably, the ZrC 2 monolayer exhibits remarkable multifunctional catalytic activity, making it a prospective activator for overall water splitting (0.01 eV for HER, 0.72 V for OER and 0.52 V for ORR). These findings offer valuable insights into the design of advanced electrocatalysts, providing new strategies for improving catalytic efficiency in sustainable energy applications.