Boosted nitrate electroreduction to ammonia on Fe-doped SnS2 nanosheet arrays rich in S-vacancies

Abstract

The electrochemical nitrate reduction reaction (NO₃RR) not only holds great potential for the removal of NO₃⁻ contaminants from the environment, but also potentially provides a renewable-energy-driven NH₃ synthesis method to replace the Haber–Bosch process. Herein, we report that Fe-doped SnS₂ nanosheets enriched with S-vacancies can be used as an efficient NO₃RR catalyst, showing a high NH₃ yield of 7.2 mg h⁻¹ cm⁻² (at −0.8 V) and a faradaic efficiency of 85.6% (at −0.7 V). Density functional theory (DFT) calculations revealed that S-vacancies on Fe–SnS₂ serve as the main active sites for the NO₃RR and the Fe-doping can further regulate the electronic structure of S-vacancies to optimize the binding energies of NO₃RR intermediates, resulting in reduced energy barriers and enhanced NO₃RR activity.