In situ constructed dynamic Cu/Ce(OH) interface for nitrate reduction to ammonia with high activity, selectivity and stability

Electrocatalytic nitrate reduction (NO3−RR) offers a promising technique for the removal and utilization of nitrate in water. However, the performance of current catalysts is still limited mainly due to the unfavorable interface that largely determines the reaction efficiency and selectivity. Here we present an in situ dynamic reconstruction strategy to enhance the NO3−RR by constructing Cu/Ce(OH)x catalyst with abundant interfacial active sites. The Cu/Ce(OH)x catalyst was in situ formed through dynamic reconstruction of Cu2Cl(OH)3/Ce(OH)x heterostructure during electrochemical NO3−RR process. The catalyst exhibits high performance with NO3− conversion of 100.0%, NH3 selectivity of 97.8%, NH3 Faradaic efficiency of 99.2% and long stability, which is among the state-of-the-art catalysts in neutral media. Both experimental and theoretical results demonstrate that the Cu and Ce sites at the interface can operate cooperatively to promote the adsorption and activation of NO3−, and lower the formation energy of key intermediate *HNO. Meanwhile, the hydrogen evolution reaction is also greatly suppressed due to the high H* binding strength at the interface. The strategy can be extended to other catalytic systems and opens a new avenue for the design of efficient electrocatalysts.