Simultaneously Photocatalytic H2 Production and C–C Coupling of 4-Pyridinemethanol on Pt Doped CdS/TiO2 Heterojunction

Abstract The synergistic coupling of photocatalytic hydrogen production with high-value-added organic conversion provides a new research direction for the efficient use of solar energy and green chemical synthesis. However, key challenges remain in the same catalytic system, such as severe carrier recombination and difficulty in precisely controlling the interfacial reaction pathways. To address these issues, we construct CdS/TiO2 heterojunction photocatalysts with Pt species introduced by ion exchange and photodeposition. As a result, the Cd(Pt)S/TiO2–Pt composite photocatalyst is successfully prepared. Under visible light irradiation, the catalyst achieves highly selective conversion of 4-pyridinemethanol to the C–C coupling product 1, 2-di(4-pyridyl)-1,2-ethanediol, with a selectivity of 89.22%. Under optimized reaction conditions, the maximum H2 production rate of the catalyst reaches 4.66 mmol·g–1·h–1. Mechanistic studies show that the photogenerated holes enriched on the surface of Cd(Pt)S drive the sp3 C–H dehydrogenation of 4-pyridinemethanol to form •CH(OH)C5H4N radicals, which then undergo radical coupling to form new C–C bonds. Meanwhile, the photogenerated electrons transfer through TiO2 to the Pt active sites to participate in hydrogen evolution. This study provides new insights into regulating the selective conversion of radicals via interfacial electronic engineering and designing photocatalytic coupled reaction systems.