Cu₂₊₁O/Ag Heterostructure for Boosting the Electrocatalytic Nitrate Reduction to Ammonia Performance

Electrocatalytic nitrate reduction reaction (ENO₃RR) is an alternative, sustainable, and environmentally friendly value-added NH₃ synthesis method under ambient conditions relative to the traditional Haber-Bosch process; however, its low NH₃ yield, low Faradaic efficiency (FE), low selectivity, and low conversion rate severely restrict the development. In this work, a Cu₂₊₁O/Ag-CC heterostructured electrocatalyst was successfully fabricated by constructing a heterogeneous interface between Cu₂₊₁O 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 Cu₂₊₁O and Ag, which enhances the material conductivity, accelerates the interfacial electron transfer, and exposes more active sites, thus improving the performance of ENO₃RR. Such Cu₂₊₁O/Ag-CC manifests a high NH₃ yield of 2.2 mg h^-1 cm^-2 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 NO₃^--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 ENO₃RR but also an effective strategy for the construction of ENO₃RR electrocatalysts for electrocatalytic applications.