Engineering oxygen vacancies in NiCoAl-LDH@NiP hybrid catalysts for an efficient hydrogen evolution reaction

Replacing platinum-based electrodes with non-precious metal-layered double hydroxides (LDHs) has gathered significant attention in the field of the electrocatalytic hydrogen evolution reaction (HER). LDHs composed of Ni, Al and Co are emerging as potent electrocatalysts due to their inimitable features such as composition, surface morphology and abundant electrocatalytically active sites. A key strategy to enhance their overall electrocatalytic performance involves generating oxygen vacancies by varying the cobalt content. Irregular lamellar morphology of the NiCoAl LDH provides a larger surface area for the reaction to occur. Additionally, incorporating an NiP matrix support improves mechanical stability and conductivity. Irregular NiCoAl LDH flakes grown on the globular NiP matrix lowers the charge transport distance and enhances the overall catalytic activity of the electrode towards the alkaline HER. By tuning the NiCoAl content in the NCA@NP electrode, a low η₁₀ value of 135 mV and a low Tafel slope of 95 mV dec^-1 are achieved. The interaction between NiCoAl and the NiP matrix improves the number of catalytically active sites, thus promoting charge transport kinetics. The NCA@NP electrode offers a scalable and promising option for the development of HER electrodes with significant electrocatalytic performance.