Cu/CuO_<i>x</i> In-Plane Heterostructured\nNanosheet Arrays with Rich Oxygen Vacancies Enhance Nitrate Electroreduction\nto Ammonia

Abstract

The artificial ammonia synthesis via electrochemical\nnitrate reduction\nhas met increasing research interest, but it is still necessary to\ndevelop advanced catalysts with high nitrate-to-ammonia capability.\nHerein, we propose and demonstrate a one-step method to construct\nbinder-free Cu foam-supported oxygen vacancy-rich Cu/CuO_<i>x</i> in-plane heterostructured nanosheet arrays (Cu/CuO_<i>x</i>/CF). In addition to exposing ample active\nsites, the two-dimensional nanosheet morphology greatly facilitates\nthe mass/charge-transfer process during electrocatalysis. Besides,\nthe in-plane heterojunctions and rich oxygen vacancies induced synergistic\neffect can modulate the electronic structure of active sites and thus\ntune the adsorption properties of the reactant intermediates and inhibit\nthe formation of undesirable byproducts, which is conducive to the\nfurther improvement of nitrate reduction activity. As a result, these\nadvantages endow the Cu/CuO_<i>x</i>/CF with superior\nperformance for ammonia synthesis via nitrate electroreduction, achieving\nhigh ammonia selectivity (95.00%) and Faradaic efficiency (93.58%).