Tuning the electronic structure of nickel-cobalt spinels via cerium ion doping on binder-free nickel foam for enhanced electrochemical activity in methanol oxidation-assisted hydrogen production: Synergistic experimental and DFT insights

The most promising method for producing green hydrogen, which is both environmentally friendly and efficient, is to split water using an electrocatalytic process. Developing a highly efficient and cost-effective catalyst that promotes the hydrogen evolution reaction (HER) is a persistent and significant challenge. Herein, the Ce-doped NiCo₂O₄ on nickel foam (NiCe_xCo_2-xO₄@NF (0^_.00≤x^_≤0.08)) electrocatalyst with compactly packed vertically oriented growth of nanorods and an optimized concentration of Ce (x = 0.04) achieved the lowest overpotential of 265 mV for HER. Additionally, the same optimized electrocatalyst required only 1.32 V potential for the methanol oxidation reaction (MOR) to achieve the current density of 20 mA/cm². The findings suggest that modifying the electronic configuration of the NiCo₂O₄@NF electrocatalyst by altering the Ce doping levels significantly enhances catalytic efficiency and prolongs catalyst durability. The electrocatalyst NiCe_xCo_2-xO₄@NF (x = 0.04) displayed good catalytic performance in the HER process, owing to metal redox couples (Ce³⁺/Ce⁴⁺), surface oxygen vacancies, and vertical alignment of nanorods with a significant active surface area. Density functional theory examines how Ce doping influences the activity of HER and the spin-dependent electronic structure of CN systems that have adsorbed hydrogen and water molecules. Our findings indicate that raising the concentration of the Ce dopant improves catalytic performance and HER activity. These findings highlight the important role that Ce dopants play in changing the electrical and catalytic characteristics of CNs for HER applications.