Concentration Effects of Co and Cu Dopants in β-Ni(OH) ₂ on Ammonia Oxidation Activity and Selectivity

The electrochemical ammonia oxidation reaction offers a potential approach for energy generation or remediation of aqueous nitrogenous waste. The development of affordable and stable electrocatalysts is needed for the widespread use of the AOR. Ni-based electrodes offer a cheaper alternative to other electrocatalysts while having moderate activity and long-term stability. This work uses density functional theory to investigate the effect of Co and Cu surface dopants at varying concentrations in β-Ni(OH)2 and their impact on ammonia oxidation activity and selectivity. The introduction of Co doping to β-Ni(OH)2 reduced the *NH2 to *NH free energy, leading to lowered limiting potentials for N2(g) formation. Cu doping led to the reduction in energy required for the hydroxylation of *NO to *NO2H. This hydroxylation step is the typical limiting potential step for the production of NO2–(aq) and suggests that Cu doping may impact the selectivity toward NO2–(aq) production. This work begins to understand the effect of surface doping β-Ni(OH)2 in differing ratios in an attempt to improve the performance of Ni-based catalysts.