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

Abstract

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 CoS₂ polyhedra (Mo-CoS₂) by encapsulating polyoxometalate (POM, H₃PMo₁₂O₄₀) 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-CoS₂ 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-CoS₂ 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.