The generation of green hydrogen as a renewable energy carrier via water electrolysis is pivotal in addressing the interconnected challenges posed by fossil fuels. To date, two main techniques, namely alkaline water electrolysis (AWE) and proton exchange membrane water electrolysis (PEMWE), stand out as the most viable options for industrial-scale clean hydrogen production. AWE typically offers higher material compatibility, enabling the use of earth-abundant transition metals to reduce capital expenses. Meanwhile, the unique character of AWE also contributes to a longer electrolyzer lifetime of up to 10 years. However, the ongoing request for highly effective OER catalysts to improve the overall H2 production efficiency remains a limiting factor for transition metal-based AWE systems. Compared to AWE, PEMWE provides the advantage of operating water electrolysis at high current densities (>2 A/cm 2 ), while its locally acidic media calls for high-yield catalysts, typically restricted to costly platinum group metals (PGMs). Against this backdrop, development of new catalysts based on earth-abundant transition metals, which display high catalytic activity under both alkaline and acidic conditions, presents an alternative option for advancing the commercialization of industrial-scale water electrolysis.