Structuring MoO3-polyoxometalate hybrid superstructures to boost electrocatalytic hydrogen evolution reaction

Improving the surface atoms utilization efficiency of catalysts is extremely important for large-scale H₂ production by electrochemical water splitting, but it remains a great challenge. Herein, we reported two kinds of MoO₃-polyoxometalate hybrid nanobelt superstructures (MoO₃-POM HNSs, POM = PW₁₂O₄₀ and SiW₁₂O₄₀) using a simple hydrothermal method. Such superstructure with highly uniform nanoparticles as building blocks can expose more surface atoms and emanate increased specific surface area. The incorporated POMs generated abundant oxygen vacancies, improved the electronic mobility, and modulated the surface electronic structure of MoO₃, allowing to optimize the H* adsorption/desorption and dehydrogenation kinetics of catalyst. Notably, the as-prepared MoO₃-PW₁₂O₄₀ HNSs electrodes not only displayed the low overpotentials of 108 mV at 10 mA/cm² current density in 0.5 mol/L H₂SO₄ electrolyte but also displayed excellent long-term stability. The hydrogen evolution reaction (HER) performance of MoO₃-POM superstructures is significantly better than that of corresponding bulk materials MoO₃@PW₁₂O₄₀ and MoO₃@SiW₁₂O₄₀, and the overpotentials are about 8.3 and 4.9 times lower than that of single MoO₃. This work opens an avenue for designing highly surface-exposed catalysts for electrocatalytic H₂ production and other electrochemical applications.