Exploring two-dimensional carbides as highly active catalysts for the oxygen reduction reaction: A density functional theory approach

Abstract

Investigating highly efficient electrocatalysts for fuel cells is urgent. Herein, the oxygen reduction reaction performance of a group of MXene-like carbide two-dimensional materials, including CrC2, MnC2, FeC2, TcC2, HfC2, and WC2, was investigated through first-principles calculations. In these systems, transition metals are sandwiched between C2 dimers at the top and those at the bottom of a MC2 structure. Among the investigated systems, WC2 exhibits the low overpotential of 0.42 V compared with the other systems. The overpotential values of CrC2, MnC2, FeC2, TcC2, and HfC2 are 1.04, 1.16, 1.56, 1.39, and 1.69 V, respectively. In addition, two different catalytic mechanisms based on single and double active sites were compared to each other for TcC2 and WC2, revealing that the mechanism based on dual-active-sites is more favorable than the mechanism based on a single-active-site for these two systems. Our study suggests that a WC2 monolayer can be a potential electrocatalyst for oxygen reduction.