Enhanced electrocatalytic nitrate-to-ammonia performance from Mott–Schottky design to induce electron redistribution

Abstract

Constructing highly efficient electrocatalysts via interface manipulation and structural design to facilitate rapid electron transfer in electrocatalytic nitrate-to-ammonia conversion is crucial to attaining superior NH₃ yield rates. Here, a Mott–Schottky type electrocatalyst of Co/In₂O₃ with a continuous fiber structure has been designed to boost the electrocatalytic nitrate-to-ammonia performance. The optimized Co/In₂O₃-1 catalyst exhibits an impressive NH₃ yield rate of 70.1 mg cm⁻² h⁻¹ at −0.8 V vs. the reversible hydrogen electrode (RHE), along with an NH₃ faradaic efficiency (FE) of 93.34% at 0 V vs. RHE, greatly outperforming the single-component Co and In₂O₃ samples. The yield rate of Co/In₂O₃-1 is also superior to that of most currently reported Co-based catalysts and heterostructured ones. Evidence from experiments and theoretical results confirms the formation of a Mott–Schottky heterojunction, which achieves a Co site enriched with electrons, coupled with an In₂O₃ facet enriched with holes, inducing an electron redistribution to promote the utilization of electroactive sites. Consequently, the reaction energy barrier for nitrate-to-ammonia conversion is significantly reduced, further enhancing its yield efficiency.