Efficiency enhancement of nitrate electroreduction to ammonia by introducing Co(OH)2 nanosheets on Cu2O microsphere: Increase supply and reduce resistance

Electrocatalytic NO 3 − reduction reaction (NO 3 RR) has attracted much attention as a promising NH 3 synthesis pathway, and Cu-based catalysts have been proven to lead to advantages in nitrate reduction . However, the active hydrogen (H*) produced by the Cu-based catalyst is insufficient to satisfy the hydrogenation process of the NO 3 RR intermediate, resulting in a large generation of NO 2 − . In this paper, the Co(OH) 2 /Cu 2 O heterojunction was constructed to improve the kinetics of H 2 O dissociation to generate H* and Co(OH) 2 /Cu 2 O (5.87 %) showed lower faradaic efficiency (FE) of NO 2 − than Cu 2 O (50.95 %). Mechanistic studies reveal that the introduction of Co(OH) 2 can help Cu 2 O lower the energy barrier of H 2 O dissociation, greatly boosting the supply of active hydrogen (H*). Not only that, but the reaction energy barriers of *NO to *NOH can be greatly reduced. The final twofold reason works together to greatly improve the efficiency of hydrogenation of NO 2 − , largely solving the problem of FE reduction due to the delayed consumption of NO 2 − , thus realizing improved performance.