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.