CuO/Ag Heterostructure for Boosting the Electrocatalytic Nitrate Reduction to Ammonia Performance.

Electrocatalytic nitrate reduction reaction (ENORR) is an alternative, sustainable, and environmentally friendly value-added NH synthesis method under ambient conditions relative to the traditional Haber-Bosch process; however, its low NH yield, low Faradaic efficiency (FE), low selectivity, and low conversion rate severely restrict the development. In this work, a CuO/Ag-CC heterostructured electrocatalyst was successfully fabricated by constructing a heterogeneous interface between CuO and Ag for selective electrochemical nitrate-to-ammonia conversion. The construction of the heterogeneous interface effectively promotes the synergistic effect of the catalytically active components CuO and Ag, which enhances the material conductivity, accelerates the interfacial electron transfer, and exposes more active sites, thus improving the performance of ENORR. Such CuO/Ag-CC manifests a high NH yield of 2.2 mg h cm and a notable ammonia FE of 85.03% at the optimal applied potential of -0.74 V vs RHE in a relatively low concentration of 0.01 M NO-containing 0.1 M KOH. Moreover, it shows excellent electrochemical stability during the cycle tests. Our study not only provides an efficient catalyst for ammonia electro-synthesis from ENORR but also an effective strategy for the construction of ENORR electrocatalysts for electrocatalytic applications.