Engineered Framework Photocatalysts for Green H₂O₂ Synthesis: Overcoming Fundamental Barriers With MOFs, COFs, and...

Hydrogen peroxide (H₂O₂) is an important green oxidant used in chemical synthesis and environmental remediation. However, its conventional anthraquinone-based production is energy-intensive, centralized, and environmentally demanding. Solar-driven photocatalytic H₂O₂ synthesis through selective oxygen reduction and water oxidation has emerged as a sustainable alternative, although practical implementation remains hindered by rapid charge recombination, limited oxygen activation, sluggish mass transfer, and catalyst-induced H₂O₂ decomposition. In this context, porous framework materials including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and hydrogen-bonded organic frameworks (HOFs) have attracted significant attention due to their tunable porosity, programmable active sites, and versatile electronic structures. This review provides a unified and mechanistically informed analysis of framework-based photocatalysts for H₂O₂ production, correlating framework architecture, defect engineering, heterojunction formation, and active-site coordination with photocatalytic performance. Key challenges associated with light harvesting, charge separation, oxygen transport, product stability, and long-term durability are critically discussed alongside important benchmarking metrics such as apparent quantum yield and solar-to-chemical conversion efficiency. Furthermore, the review highlights scalability considerations and emerging design strategies required to transition framework-based photocatalysts from laboratory studies toward decentralized and industrially relevant H₂O₂ production systems. This work provides a comprehensive roadmap for the rational development of next-generation porous photocatalysts for a sustainable economy.