Effect of pH on the Electrochemical Behavior and Nitrogen Reduction Reaction Activity of Ti 2 N Nitride MXene

Abstract Nitrogen reduction reaction (NRR) is used to convert nitrogen (N 2 ) to ammonia (NH 3 ) at ambient conditions. In general, acidic electrolytes are used to provide protons (H + ), however, this leads to low selectivity due to H 2 formation via the hydrogen evolution reaction (HER). Recently, it is shown that Ti 2 N MXene is active and selective for NRR in acidic electrolyte, and operates through a Mars‐van Krevelen (MvK) mechanism. However, the effect of pH on its catalytic performance is not well understood. Here, experiments are performed in varying pH values and relations are developed between pH and performance. The findings of this study indicate that the lowest NRR onset occurs within pH 2 systems exhibiting a nonlinear trend. However, as pH decreases, overpotential decreases, and kinetics increase due to H + participation. FE values are found to increase as pH increased. These findings will be extended to other materials to design optimal electrolytic systems for NRR.