CoS₂@TiO₂ nanoarray: a heterostructured electrocatalyst for high-efficiency nitrate reduction to ammonia

Electrochemical nitrate (NO₃^-) reduction emerges as a promising strategy to maintain the balance of the global nitrogen cycle and an alternative to nitrogen electroreduction for ambient ammonia (NH₃) synthesis. However, the complicated multiple-electron transfer process of NO₃^--to-NH₃ conversion demands catalysts with high selectivity for NH₃ production. Herein, CoS₂ nanoparticle decorated TiO₂ nanobelt array on a titanium plate (CoS₂@TiO₂/TP) is reported as a superb electrocatalyst for the NO₃^- reduction reaction. In 0.1 M NaOH containing 0.1 M NO₃^-, CoS₂@TiO₂/TP offers a large NH₃ yield of 538.21 μmol h^-1 cm^-2 at -0.7 V vs. reversible hydrogen electrode (RHE) and a high faradaic efficiency of 92.80% at -0.5 V vs. RHE. Additionally, it also shows strong stability for the 20 h electrolysis test.