Selective Oxidation Strategies for Cost-Efficient Green Hydrogen Production via Hybrid Water Electrolysis

Sustainable hydrogen production is essential for decarbonizing energy and chemical manufacturing; however, conventional water electrolysis is limited by the high thermodynamic and kinetic demands of the oxygen evolution reaction (OER). Hybrid water electrolysis addresses this challenge by replacing the OER with more favorable organic oxidation reactions (OORs), reducing energy input while valorizing or remediating abundant biomass- and waste-derived feedstocks. This review presents the first unified assessment that integrates techno-economic analysis with mechanistic insight and electrocatalyst design principles to identify the most viable OOR pathways. We evaluate key substrates, including glycerol, 5-hydroxymethylfurfural, urea, methanol, and ethanol, and summarize advances in noble and non-noble metal catalysts enabling selective partial oxidation at reduced voltages. The remaining challenges in catalyst stability, product separation, membrane durability, and system integration are critically examined. Overall, this review provides a comprehensive framework for guiding the development and industrial deployment of hybrid electrolyzers for low-carbon, value-added hydrogen production.

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