Theoretical Study of In_xRu_y Alloys for Efficient Electrocatalytic Reduction of Nitrate to Ammonia

The electrochemical reduction of nitrate to ammonia is considered a feasible strategy to address the imbalance of the global nitrogen cycle by eliminating N-containing pollutants in wastewater while producing ammonia in a sustainable way. In this work, we systematically investigate the reduction of nitrate to ammonia on p-block indium (In), noble metal ruthenium (Ru), and their alloys (InRu₃, In₃Ru). We found that pure In and Ru candidates exhibit various performances for nitrate reduction with low limiting potentials for the potential-determining step of −0.31 V and −0.14 V, respectively. However, the incorporation of In into Ru to create alloys leads to excellent activity for the reduction of nitrate to ammonia. Ammonia production on InRu₃ and In₃Ru alloys demonstrates higher catalytic activity and selectivity as the byproducts of NO₂ and NO can be inhibited, while the parasitic hydrogen evolution reaction (HER) can also be significantly suppressed. Our work not only proposes efficient electrocatalysts for nitrate reduction but also provides a new strategy for the rational design of alloy catalysts for improved catalytic performance.