Two-Dimensional Molybdenum Carbide (MXene) as an Efficient Electrocatalyst for Hydrogen Evolution

The hydrogen evolution reaction (HER) is an important energy conversion process that underpins many clean energy technologies including water splitting. Herein, we report for the first time the application of two-dimensional (2D) layered transition metal carbides, MXenes, as electrocatalysts for the HER. Our computational screening study of 2D layered M 2 XT x (M = metal; X = (C, N); and T x = surface functional groups) predicts Mo 2 CT x to be an active catalyst candidate for the HER. We synthesized both Mo 2 CT x and Ti 2 CT x MXenes, and in agreement with our theoretical predictions, Mo 2 CT x was found to exhibit far higher HER activity than Ti 2 CT x . Theory suggests that the basal planes of Mo 2 CT x are catalytically active toward the HER, unlike in the case of widely studied MoS 2, in which only the edge sites of the 2H phase are active. This work paves the way for the development of novel 2D layered materials that can be applied in a multitude of other clean energy reactions for a sustainable energy future.