Theoretical study of single-nonmetal-modified V2CO2 MXene as an efficient electrocatalyst for overall water splitting

Abstract

The electrocatalytic water splitting consists of two half-reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which require low-cost and highly activity catalysts. Two-dimensional transition metal carbon-nitride (MXenes) are considered as the potential catalysts candidates for HER and OER due to their unique physical and chemical properties. In this work, using density functional theory (DFT), we have investigated the effect of single non-metal (NM, NM = B, N, P, and S) atoms doping, strain, and terminal types on the HER and OER activities of V2CO2 MXene. Results indicated that P doping V2CO2 (P/V2CO2) has best HER performance at hydrogen coverage of θ = 1/8, and N doping V2CO2 (N/V2CO2) has best OER performance among the studied systems. In addition, it can be found that there is a strong correlation between the ΔGH and strain, ΔGH and valence charges of the doped atoms after applying strain to the doping structures, with the correlation coefficient (R2) about equal 1. Moreover, the mixed terminal can enhance the performances of HER and OER, which obey the follow rules: mixed terminal (O∗ and ∗OH) > original terminal (O∗) > ∗OH terminal. The ab initio molecular dynamics simulations (AIMD) results revealed that the single non-metallic doped structures are stable and can be synthesized experimentally at different terminals.