Sulfophobic and Vacancy Design Enables Self-Cleaning Electrodes for Efficient Desulfurization and Concurrent Hydrogen Evolution with Low Energy Consumption

Sulfide oxidation reaction (SOR) is one central step of electrochemical desulfurization and sulfur-based batteries. However, the electrochemical performance of desulfurization and sulfur batteries has been severely hindered by sulfur passivation. Here, a discovery of sulfophobic phenomenon of electrocatalysts having weak interaction to sulfur species is reported. A self-cleaning NiS2 electrode is developed to avoid the long-perplexing passivation issue of solid sulfur during the SOR. Furthermore, sulfur-vacancies are engineered into NiS2 lattice to synthesize v-NiS2 for the hydrogen evolution reaction (HER). The resultant lattice expansion and electron redistribution can adjust the adsorbed hydrogen to reach a nearly thermos-neutral state, enabling high catalytic activity for the HER. By coupling the HER and SOR, efficient desulfurization and simultaneous hydrogen production is demonstrated. Bifunctional NiS2 enables such a one-stone-kills-two-birds strategy to realize continuous electrochemical desulfurization with superior energy efficiency (1.05 g(sulfur) Wh(-1)). As a general design principle, sulfophobic electrocatalysts can improve the properties of lithium-sulfur batteries by minimizing the passivation of S-8 during charge. In brief, interfacial interaction between electrocatalysts and sulfur species are systematically investigated and a sulfophobic strategy to significantly enhance the electrochemical performance of the SOR is offered