Solar‐Driven Photocatalytic H 2 O 2 Production: Mechanistic Foundations, Catalyst Design, Performance Benchmarking, and Sustainable Applications

Hydrogen peroxide (H 2 O 2 ) is a clean oxidant, disinfectant, and candidate liquid energy carrier, yet its industrial manufacture remains dominated by the energy‐intensive anthraquinone process. Solar photocatalytic H 2 O 2 synthesis offers a decentralized alternative that could combine water, molecular oxygen, and sunlight under ambient conditions. The field now spans inorganic semiconductors, graphitic carbon nitride (g‐C 3 N 4 ), covalent organic frameworks (COFs), heterojunctions, and other porous frameworks. This review connects reaction mechanisms, catalyst design, performance testing, and emerging applications across these major platforms. We examine the two‐electron oxygen reduction reaction (2e − ORR), two‐electron water oxidation reaction (2e − WOR), and dual‐channel photosynthesis. We then assess how intrinsic electronic and structural properties govern O 2 adsorption, intermediate stabilization, proton‐coupled electron transfer, selective two‐electron conversion, product release, and H 2 O 2 loss. Performance is interpreted together with the water matrix, donor use, O 2 supply, illumination, normalization basis, and analytical method. Finally, we consider collected H 2 O 2 production, in situ utilization, coupled synthesis, and multiscale optimization from molecular sites to reactors. Mechanistic verification, long‐term stability, mass transfer, and transparent reporting remain the central challenges for practical solar H 2 O 2 production.