Photodeposited Ag–Pd on PMo12/g-C3N4, a Ternary Nanocomposite for Photocatalytic H2 Production

Abstract A ternary Ag–Pd/PMo12/g-C3N4 photocatalyst for visible-light-driven formic acid dehydrogenation was synthesized via a photodeposition strategy that eliminates the need for external chemical reductants such as NaBH4 or hydrazine. In this approach, Keggin-type PMo12 species are photoreduced by photogenerated electrons from g-C3N4 under UV irradiation and subsequently mediate electron transfer for the in situ formation of Ag–Pd nanoalloys at near-room temperature (30 °C). The high negative charge density of PMo12 anchored on porous g-C3N4 is proposed to promote nucleation of the bimetallic phase in proximity to polyoxometalate sites, consistent with the observed uniform dispersion and strong interfacial interactions. Under visible-light irradiation, the optimized catalyst generates approximately 75 mL of gas within 70 min, corresponding to a mass-normalized gas evolution rate of 5.26 × 105 μmol g–1 h–1. The catalyst outperforms the corresponding monometallic and binary systems while maintaining stable activity over five consecutive cycles, consistent with the formic acid dehydrogenation pathway. This work provides an environmentally benign strategy for engineering multicomponent photocatalysts for visible-light-driven FA dehydrogenation.