Theoretical Study of Cu-ⅢA Binary Alloy Catalysts for Electrochemical Nitrate Reduction to Ammonia

Electrocatalytic reduction of nitrate to ammonia (NO3RR) emerged as a promising approach for wastewater purification and NH3 electrosynthesis. Unfortunately, the catalytic performance of electrocatalysts is hindered by poor activity and selectivity for practical application. Herein, three types of Cu-based alloys, constituted by post-transition metals (Al, Ga and In), were investigated for the NO3RR process. Using density functional theory (DFT) calculations, the reaction pathways for three catalysts along with Gibbs free energy evolution were identified, where the enhanced activity was observed in the sequence of Al, Ga and In with limiting potentials of -0.77 V, -0.21 V and -0.18 V, respectively. The favourable nitrate reduction is due to enhanced electronic distribution and conductivity. The relationship between nitrate adsorption and limiting potential demonstrated that moderate nitrate adsorption is associated with higher activity. In addition, the proton adsorption and by-product formation (N2O) on Ga2Cu(100) was found to be difficult. The promising candidate of Cu-based bimetallic systems with excellent NO3RR performance was proposed, thus providing insights into the rational design of novel catalytic materials through the p-block alloying strategy.