FeS₂@TiO₂ nanobelt array enabled high-efficiency electrocatalytic nitrate reduction to ammonia

Nitrate (NO₃⁻), which exists in both surface water and underground water, is harmful to the environment and human body. Ammonia (NH₃) is a kind of necessary produced chemical for industry and daily life. Electrochemical NO₃⁻ reduction can eliminate hazardous NO₃⁻ and produce value-added NH₃ at the same time under ambient conditions but requires efficient catalysts for the NO₃⁻ reduction reaction (NO₃RR) with high selectivity. Herein, we report on the development of FeS₂ nanoparticles on TiO₂ nanobelt array (FeS₂@TiO₂) as an earth-abundant NO₃RR electrocatalyst. It shows superior electrocatalytic performance with a large NH₃ yield of 860.3 μmol h⁻¹ cm⁻² at −0.7 V and a high faradaic efficiency of 97.0% at −0.4 V versus reversible hydrogen electrode in 0.1 M NaOH with 0.1 M NO₃⁻. The theoretical calculations reveal the mechanisms of the enhanced NO₃RR performance of FeS₂@TiO₂.