Recent Progress in Nonsacrificial H2O2 Generation Using Organic Photocatalysts and In Situ Applications for Environmental Remediation

Conspectus The photocatalytic generation of hydrogen peroxide (H 2 O 2 ) through the utilization of only H 2 O, O 2, and sunlight represents an energy-efficient and ecofriendly innovation in pursuit of a sustainable society. Despite significant efforts that have been directed toward the development of H 2 O 2 generation via photocatalysis, the solar-to-chemical conversion (SCC) efficiency has not yet reached the levels required for large-scale practical applications. Consequently, there is an urgent demand to develop and design novel photocatalysts characterized by several key attributes: high catalytic activity, cost-effectiveness, and good stability. However, traditional inorganic photocatalysts, such as TiO 2, have exhibited limited activity, partly attributable to the potential decomposition of H 2 O 2 caused by metal cations. Recent research has found organic photocatalysts as highly promising candidates to address these limitations. Organic materials offer several remarkable advantages for photocatalysis, including narrow bandgap, adjustable band edge potentials, the ability to control surface configurations for use as active sites, and the potential for rational design of structural units that promote efficient charge separation and transfer. In the field of photocatalytic H 2 O 2 generation without sacrificial reagents, efficient organic photocatalysts have been widely studied, and various strategies to improve the activity and stability of organic photocatalysts have been explored. These strategies include the construction of donor–acceptor structures, the design of conjugated structures, the incorporation of heteroatoms, the enhancement of the internal electric field, and the substitution of functional groups. Currently, organic materials have exhibited exceptional activity, far exceeding that of well-established TiO 2 . In this Account, we introduce state-of-the-art organic materials for H 2 O 2 generation based on our recent works and typical results from other groups. This classification system encompasses the anthraquinone-mediated oxygen reduction reaction (ORR), the radical-related ORR, the water oxidation reaction (WOR), and the dual ORR and WOR pathways. Through this classification, we delve into essential kinetic parameters, such as production rate, apparent quantum efficiency (AQE), and SCC efficiency that have been achieved. Additionally, we highlight the early exploration of in situ utilization of generated H 2 O 2 for environmental remediation. Furthermore, we outline forthcoming challenges in the field, including suboptimal solar energy utilization, the need for a clearer understanding of the structure–activity relationship, and insufficient research on in situ H 2 O 2 utilization. In conclusion, this Account makes a substantial contribution to the field by providing a comprehensive overview of recent advancements based on typical works from us and other groups, addressing current challenges, and suggesting areas for future research in the development of organic photocatalysts for H 2 O 2 generation. The ultimate goal is to drive forward the practical applications of organic semiconductor materials in the environmental and energy fields, thereby advancing the cause of sustainable energy production and environmental remediation.