Design strategies, methods, and photophysical insights in polymeric photocatalysts for solar-driven hydrogen evolution

Solar-driven hydrogen evolution is emerging as a pivotal strategy in the sustainable energy transition, offering a viable pathway for renewable hydrogen production. Inorganic photocatalysts, such as metal oxides, sulfides, and carbon-based materials, have been extensively studied; however, their performance is often limited by poor tunability of energy levels and structures, low processability, and inadequate utilization of visible light. In contrast, polymeric photocatalysts offer distinct advantages, including precise molecular tunability, scalable fabrication via solution processing, and adjustable energy levels for optimized solar absorption. This review highlights recent advances in polymeric photocatalysts, with particular emphasis on molecular- and particle-level design strategies, fabrication methodologies, and photophysical insights. Molecular design approaches, such as backbone engineering, side-chain modification, and heteroatom incorporation, are discussed alongside particle-level optimization through control of size, morphology, and molecular ordering. Emerging fabrication techniques, including direct polymer dispersions and nanoparticle-based processing, are examined in relation to their effects on dispersibility, light harvesting, and catalytic activity. Photophysical studies are also emphasized to elucidate charge-carrier dynamics and to establish structure–property–performance correlations. Finally, evaluation methodologies, such as hydrogen evolution performance metrics, benchmarking practices, and ongoing challenges in standardization, are critically assessed. This review aims to synthesize current achievements and provide perspectives to guide future research toward the practical implementation of polymeric photocatalysts for solar-driven hydrogen evolution.