Density Functional Theory Approximations and Experimental Investigations on Co_1–xMo_xTe₂ Alloy Electrocatalysts Tuning the Overall Water Splitting Reactions

Understanding the relationship between electronic structure, surface characteristic, and reaction process of a catalyst helps to architect proficient electrodes for sustainable energy development. The highly active and stable catalysts made of earth-abundant materials provide a great endeavor toward green hydrogen production. Herein, we assembled the Co 1– x Mo x Te ( x = 0–1) nanoarray structures into a bifunctional electrocatalyst to achieve high-performance hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics under alkaline conditions. The designed Co 0.75 Mo 0.25 Te and Co 0.50 Mo 0.50 electrocatalysts require minimum overpotential and Tafel slope for high-efficacy HER and OER, respectively. Furthermore, we constructed a Co 0.50 Mo 0.50 Te 2 ∥Co 0.50 Mo 0.50 Te 2 device for overall water splitting with an overpotential of 1.39 V to achieve a current density of 10 mA cm –2, which is superior to noble electrocatalyst performance, with stable reaction throughout the 50 h continuous process. Density functional theory approximations and Gibbs free energy calculations validate the enhanced water splitting reaction catalyzed by the Co 0.50 Mo 0.50 Te 2 nanoarrays. The partial replacement of Co atoms with Mo atoms in the Co 0.50 Mo 0.50 Te 2 structure substantially enhances the water electrolysis kinetics through the synergistic effects between the combined metal atoms and the bonded chalcogen.