Hollow Mo Doped CoS2 Polyhedron Derived from Polyoxometalate-based Metal-Organic Frameworks for Efficient Overall Water Splitting

Graphical Phosphomolybdic acid doping and co-etching with thioacetamide at low temperatures resulted in the formation of uniformly Mo-doped CoS₂ nanoparticles exhibiting a hollow structure that increased the number of active sites and provided abundant reaction sites. In terms of performance, Mo-CoS₂ exhibits the competitive OER and HER properties for an efficient overall water splitting. Nowadays, the sluggish hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics are the key obstacles limiting the commercial application of water splitting. In this study, a size-matching strategy is proposed to construct the molybdenum-doped CoS 2 polyhedra (Mo-CoS 2 ) by encapsulating polyoxometalate (POM, H 3 PMo 12 O 40 ) guests into mesoporous zeolite imidazolium framework-67 (ZIF-67), with thioacetamide (TAA) serving as a gentle sulfur source. The catalyst exhibits a pronounced hollow structure due to the synergistic etching effects of POM and TAA, which can increase the number of active sites. Additionally, the incorporation of Mo optimizes the electronic structure, thereby improving both HER and OER performance. In alkaline electrolytes, Mo-CoS 2 delivers an overpotential of 330 mV and 269 mV for OER and HER, respectively, to produce a current density of 100 mA cm −2 . Moreover, Mo-CoS 2 demonstrates exceptional performance in overall water splitting, achieving a cell voltage of 1.55 V at 10 mA cm −2 , along with outstanding long-term stability. This study provides a promising avenue for the structural and component optimization of cobalt sulfide, which could significantly improve the efficiency of hydrogen production.