Abstract
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•Co5.47N/CoMoOx particles are fabricated by hydrothermal and nitriding treatments.•The catalyst shows high HER activity (36 mV@10 mA cm−2) in 1.0 M KOH.•The cathode in assembled electrolyzer has a low cell voltage (1.54 V@10 mA cm−2).•The strong electron interaction and abundance of oxygen vacancies among different species drive the HER performance.
Designing the basic steps of water dissociation and hydrogen desorption rationally is essential to comprehend the role of oxygen vacancies in hydrogen evolution reaction (HER). This study uses interface and defect engineering to produce monodispersed Co5.47N/CoMoOx hybrid particles on carbon cloth with abundant oxygen vacancies. The optimized Co5.47N/CoMoOx catalyst shows a low overpotential of 36 mV at 10 mA cm−2, similar to commercial Pt/C. Additionally, the overall water splitting with Co5.47N/CoMoOx as cathode has a cell voltage of 1.74 V at 100 mA cm−2, better than Pt/C(−) || RuO2(+), and operates stably for 50 h at 100 mA cm−2 without degradation, making it a promising electrocatalyst for industrial use. Experiment and DFT calculations demonstrate that strong electronic interaction between different components and rich oxygen vacancies enhance the catalyst's electrical conductivity and water dissociation. As a result, the hydrogen adsorption free energy (ΔGH*, −0.06 eV) is nearly equal to the ideal adsorption energy (0 eV), demonstrating faster hydrogen absorption/desorption kinetics for Co5.47N/CoMoOx, thus improving its HER performance.