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 Ti₂CT_x into an active electrocatalyst by the nitridation of two-dimensional (2D) titanium carbide MXene (Ti₂CT_x) nanosheets using sodium amide (NaNH₂). The addition of NaNH₂ results in the chemical bonding of Ti-N_x at 500 °C on the surface of Ti₂CT_x, 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-Ti₂CT_x (N-Ti₂CT_x) 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-Ti₂CT_x (−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.