Enhanced Electrocatalytic Activity by Chemical Nitridation of Two-Dimensional Titanium Carbide MXene for Hydrogen Evolution

Developing active and stable electrocatalysts from Earth-abundant elements is the key to water splitting for hydrogen production through electrolysis. Here, we report a strategy to turn non-electrocatalytic Ti2CTx into an active electrocatalyst by the nitridation of two-dimensional (2D) titanium carbide MXene (Ti2CTx) nanosheets using sodium amide (NaNH2). The addition of NaNH2 results in the chemical bonding of Ti–Nx at 500 °C on the surface of Ti2CTx, which was designed as an efficient electrocatalytic material for the hydrogen evolution reaction (HER). When used as an electrocatalytic material for the HER, the nitrided-Ti2CTx (N-Ti2CTx) exhibited high activity with an overpotential of −215 mV vs. NHE for the hydrogen evolution reaction (HER) at 10 mA cm−2. These values are over three times smaller than those for pristine-Ti2CTx (−645 mV vs. NHE for the HER). The as-synthesized sample showed excellent durability under acidic (0.5 M H2SO4) conditions, indicating its robust catalytic activity towards the HER. The nitridation strategy implemented here could be extended to other 2D transition metal carbide electrocatalysts to improve their catalytic performance.