Exploring structural and electronic properties of transition metal carbides (T = Ti, V, Mo, & W) as efficient catalysts for overall water splitting with the DFT study

Abstract

Earth abundant transition metal carbides (TMCs), including titanium carbide (TiC), vanadium carbide (VC), molybdenum carbide (MoC), and tungsten carbide (WC), are considered promising materials to substitute expensive novel metal Pt- and Ir-based catalysts since they can demonstrate exceptional electrocatalytic performance towards overall water splitting due to their unique electronic and structural properties. Herein, this work demonstrated the facile synthesis of different TMCs and investigated their electrocatalytic activities for alkaline water electrolysis. The prepared WC exhibited superior electrocatalytic activity towards the hydrogen evolution reaction (η₁₀₀ = 295 mV) and MoC showed excellent electrocatalytic activity towards the oxygen evolution reaction (η₁₀₀ = 373 mV), which are comparable to those of commercial Pt/C and IrO₂ catalysts, respectively. The mechanistic investigation indicated that the optimized orbital hybridization of TMCs balances the adsorption and desorption of reaction intermediates resulting in variations in their efficiency. In addition, the theoretical DFT study demonstrated the oxidative response of the prepared WC and MoC surfaces for overall water splitting by identifying the chemisorbed oxygen atoms.