Electronic Structure Modulating of W₁₈O₄₉ Nanospheres by Niobium Doping for Efficient Hydrogen Evolution Reaction

Hydrogen, known for its high energy density and environmental benefits, serves as a prime substitute for fossil fuels. Nonetheless, the hydrogen evolution reaction (HER), essential in electrolysis, encounters challenges with slow kinetics and significant overpotential, which elevate costs and reduce efficiency. Thus, developing efficient electrocatalysts to reduce HER overpotential is vital to enhance hydrogen production efficiency and minimize energy consumption. Adjusting the electronic structure of transition metal oxides via elemental doping is a potent strategy to improve the effectiveness of electrocatalysts for hydrogen evolution. In this work, we synthesized a set of niobium-doped tungsten oxides (Nb_x-W₁₈O₄₉) under anoxic conditions using a straightforward "one-pot" solvothermal approach. After doping Nb, the oxygen vacancy content inside W₁₈O₄₉ was increased, which induced a synergistic effect with the active sites of tungsten. In acidic environments, the hydrogen evolution activity of the Nb_0.6-W₁₈O₄₉ electrocatalyst is second only by 20 wt % Pt/C. It attains a current density of -10 mA cm^-2 at an overpotential of 102 mV. By comparison with W₁₈O₄₉, Nb_0.4-W₁₈O₄₉ and Nb_0.5-W₁₈O₄₉, Nb_0.6-W₁₈O₄₉ demonstrates a reduced charge transfer resistance, which significantly enhances its conductivity and the speed of electron movement across interfaces. Coupled with this feature are notably faster HER kinetics. Additionally, it exhibits excellent stability, meaning it maintains its performance and structural integrity over prolonged periods and under various operational conditions. This article provides a new perspective for discovering inexpensive and efficient hydrogen evolution electrocatalyst materials.