Sanhawat Rumporee, Wissuta Boonta, Athis Watwiangkham, Taweesak Sudyoadsuk, Khetpakorn Chakarawet, Nawaporn Vinayavekhin, Syuji Fujii, Teera Butburee,* Suwit Suthirakun,* and Junjuda Unruangsri*

This study presents a simple and effective method to boost dual photocatalysis — the simultaneous generation of hydrogen fuel and valuable chemical products using sunlight. Hybrid photocatalysts were developed by combining cadmium sulfide (CdS) quantum dots with non-conjugated poly(ionic liquid)s, specifically poly(diallyl dimethyl ammonium bromide) (P(DADMA)) and poly(1-ethyl-3-vinylimidazolium bromide) (P(VEIM)), through electrostatic assembly. These polymers serve as electron donors, significantly improving charge separation and transfer within the CdS system. The optimized CdS/P(DADMA) hybrid showed outstanding performance under visible light, producing 12.8 mmol/g/h of hydrogen and selectively converting benzyl alcohol to racemic hydrobenzoin at 12.5 mmol/g/h with 99% selectivity — a reaction typically hindered in water due to mass transfer limitations. This work offers a promising approach for designing efficient solar-powered systems for clean fuel production and green chemical synthesis, contributing to more sustainable and integrated energy–chemical solutions.