Sulfur vacancy-rich tungsten disulfide and metal–organic framework derived Co3O4 heterostructure for sulfur ion degradation-assisted efficient hydrogen production

The rapid advancement of the hydrogen economy hinges on developing efficient systems that combine the sulfion oxidation reaction (SOR) and hydrogen evolution reaction (HER) to achieve cost-effective hydrogen production. Herein, a metal–organic framework derived Co₃O₄-integrated WS₂ (CW) heterostructure with sulfur-rich vacancies was synthesized via a hydrothermal process. This ultrathin nanosheet structure afforded efficient electrocatalytic performance towards oxygen evolution reaction (OER), HER, and SOR by providing abundant active sites and optimal electronic configurations. The optimal CW heterostructure exhibited excellent OER and HER performance with lower overpotentials of 270 and 153 mV, respectively. The higher turnover frequency of the CW-2 electrocatalysts is 0.226 s⁻¹ at the potential of 1.65 V. In situ/operando X-ray absorption spectroscopy (XAS) provided detailed insights into the dynamics at the catalyst surface and structural evolution under electrochemical conditions. In situ/operando XAS demonstrated a decrease in the coordination number of W–S when the applied potential was increased to 1.55 V due to the formation of sulfur vacancies. Sulfur and metal vacancies were plausibly co-existent, as demonstrated by the variation in the coordination number for the W–S first shell with the applied voltage, and the similar trend for the W–W second shell. Because of these advantages, the CW heterostructure exhibited better electrocatalytic activity for the OER, HER, and SOR. The assembled system with the CW-2 heterostructure established a remarkably low cell voltage of 0.41 V (@ 10 mA cm⁻²) for driving the cathodic HER and anodic SOR, with high faradaic efficiency (86.27%), and exceptional durability over 80 h. The findings of this study should contribute significantly to energy-efficient hydrogen production and sustainable sulfion recycling through the development of robust and highly effective catalysts.