Cation/Anion Dual-Vacancy Pair Modulated Atomically-Thin Sex-Co3S4 Nanosheets with Extremely High Water Oxidation Performance in Ultralow-Concentration Alkaline Solutions

The density functional theory calculation results reveal that the adjacent defect concentration and electronic spin state can effectively activate the Co-III sites in the atomically thin nanosheets, facilitating the thermodynamic transformation of *O to *OOH, thus offering ultrahigh charge transfer properties and efficiently stabilizing the phase. This undoubtedly evidences that, for metal sulfides, the atom-scale cation/anion vacancy pair and surface electronic spin state can play a great role in enhancing the oxygen evolution reaction. Inspired by the theoretical prediction, interconnected selenium (Se) wired ultrathin Co3S4 (Se-x-Co3S4) nanosheets with Co/S (Se) dual-vacancies (Se-1.0-Co3S4-V-S/Se-V-Co) pairs are constructed by a simple approach. As an efficient sulfur host material, in an ultralow-concentration KOH solution (0.1 m), Se-1.0-Co3S4-V-S/Se-V-Co presents outstanding durability up to 165 h and a low overpotential of 289.5 mV at 10 mA cm(-2), which outperform the commercial Co3S4 nanosheets (NSs) and RuO2. Moreover, the turnover frequency of Se-1.0-Co3S4-V-S/Se-V-Co is 0.00965 s(-1) at an overpotential of 0.39 V, which is 5.7 times that of Co3S4 NSs, and 5.8 times that of commercial RuO2. The finding offers a rational design strategy to create the multi-defect structure in catalysts toward high-efficiency water electrolysis.

Automated summary

The density functional theory calculation reveals the importance of adjacent defect concentration and electronic spin state in enhancing the oxygen evolution reaction in metal sulfides. The construction of selenium-wired ultrathin nanosheets offers a rational design strategy for high-efficiency water electrolysis.