Activating NiO nanorods array via nitrogen ion implantation for enhanced alkaline hydrogen evolution

Developing efficient and inexpensive electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline water-electrolysis is crucial in advancing the hydrogen economy to address future energy demands. Despite their compositional and structural diversity, low cost, and eco-friendliness, earth-abundant transition metal oxide catalysts, such as NiO, have been deemed inactive for HER due to inadequate adsorption abilities, poor electrical conductivity, and limited catalytic active sites. In this study, we present a promising strategy to activate transition metal oxide catalysts for efficient HER by employing ion implantation technique. Nitrogen ion implantation with various fluences was conducted on NiO-based catalysts, comprising an array of three-dimensional NiO nanorods (NRs). N-ion implantation with an optimized fluence enables the synergistic effects of nitrogen dopants and oxygen vacancies in the NiO NRs. This leads to optimized hydrogen adsorption and electrical conductivity, resulting in significant enhancements in both HER and OER performances. Our approach offers an effective and universal methodology for designing bi-functional electrocatalysts composed of earth-abundant elements, aiming to facilitate efficient electrochemical hydrogen production.