Waste‐derived electrocatalysts for green hydrogen production: Standardized benchmarking, techno‐economic translation, and circular engineering barriers

Green hydrogen is increasingly viewed as a decarbonization pathway for refining, chemicals, steel, maritime transport, and long‐duration energy storage; however, its deployment remains constrained by electrolyzer cost, electricity price, water demand, catalyst durability, and reliance on precious or critical materials. This review evaluates waste‐derived electrocatalysts as a circular engineering strategy for water electrolysis. Recent catalysts derived from biomass, shell waste, plastics, electronic waste, and spent batteries are assessed for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water‐splitting performance. Representative reports show HER overpotentials as low as 26 mV at 10 mA cm −2 , competitive OER overpotentials in the low hundreds of millivolts at 10 mA cm −2 , and selected alkaline full‐cell voltages near 1.597 V at 10 mA cm −2 under laboratory conditions. However, most reported results remain limited to half‐cell tests, low current densities, and short stability durations of 30–125 h, well below commercial durability expectations. Therefore, this review emphasizes standardized benchmarking, feedstock pretreatment, impurity control, high‐current‐density testing, and the translation of voltage to the Levelized Cost of Hydrogen (LCOH). A practical roadmap is proposed for advancing waste‐derived electrocatalysts from promising laboratory materials to scalable electrolyzer components.