Preparation and Electrochemical Performance of N-Doped Carbon Nanospheres Supported Multiple Transition Metal Sulfides Electrocatalyst

The design and preparation of economic and efficient electrolysis water catalysts is an important part in effectively developing and utilizing hydrogen energy. In this work, novel N-doped carbon nanospheres supported multiple transition metal sulfides (NiWCoS/NC) electrocatalysts were prepared by combining the radiation oxidation synthesis and synchronous carbonization-sulfurization. Initially, the precursor material (NiWCoS/OANI, here OANI refers to oligoaniline) containing sulfur- and multiple transition metal (Ni, W, and Co) ions loaded on oligoaniline nanospheres was directly one-pot synthesized at room temperature under γ-ray radiation. Subsequently, NiWCoS/NC electrocatalysts were successfully prepared by calcining the NiWCoS/OANI precursor at 800 °C. The electrocatalytic performance of NiWCoS/NC for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) was characterized by electrochemical analysis methods including linear sweep voltammetry, cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The influence of the relative content of the loaded transition metals on the electrocatalytic performance was also investigated. The results indicate that the novel NiWCoS/NC electrocatalyst can significantly reduce the overpotential and Tafel slope for both HER and OER compared to corresponding electrocatalysts with single metal or metal sulfide component. When NiWCoS/NC with a molar ratio of 3:6:10 for W, Co, and S elements was used as electrode material, the overpotentials for HER in 0.5 mol/L H₂SO₄ and OER in 1 mol/L KOH are only 161 mV and 243 mV at a current density of 10 mA/cm², respectively. The Tafel slopes are 74 mV/dec and 88 mV/dec, respectively. The paper provides a new direction and method for the design and green facile preparation of high-efficiency overall water splitting catalysts.