Integrated Electrocatalyst–Interface–Reactor Design for Coupled H ₂ and H ₂ O ₂ Production via Water Electrolysis

The co‐electrolysis of water into hydrogen (H 2 ) and hydrogen peroxide (H 2 O 2 ) offers a transformative dual‐energy molecule strategy that simultaneously generates a high‐value reductant and oxidant from a single feedstock. This coupled pathway not only enables closed‐loop energy storage and release but also eliminates the reliance on oxygen gas or anthraquinone processes for H 2 O 2 production. However, the cogeneration of H 2 and H 2 O 2 via hydrogen evolution reaction (HER) and two‐electron water oxidation reaction (2 e − ‐WOR) presents distinct challenges in terms of reaction selectivity, interfacial charge transfer, and system integration. This review provides a comprehensive mechanistic and technological roadmap across three critical dimensions: (i) advanced electrocatalyst design strategies to tune adsorption energetics and intermediate pathways, (ii) interfacial regulation via solvation environment and electric field modulation to promote H 2 /H 2 O 2 production, and (iii) reactor engineering innovations, including membrane‐based, bipolar, and flow‐assisted systems, to address mass transport, gas separation, and electrolyte compatibility. By integrating atomistic insights with system‐level design, this work offers a unifying framework to accelerate selective and scalable H 2 /H 2 O 2 coproduction, bridging fundamental electrochemistry with practical energy conversion technologies.