Schiff-base-rich g-C_xN₄ supported PdAg nanowires as an efficient Mott–Schottky catalyst boosting photocatalytic dehydrogenation of formic acid

Abstract: Developing an efficient photocatalyst, catalyzing formic acid (FA) dehydrogenation, can satisfy the demand of the H₂ energy. Herein, a graphitic carbon nitride (g-C_xN₄)-based nanosheet (x = 3.2, 3.6 or 3.8) with melem rings conjugated by Schiff-base bond (N=C–C=N) was synthesized, tuning the bandgaps (E_g) of graphitic carbon nitride (g-C₃N₄) in the range of 1.8 < E_g < 2.7 eV, and grown PdAg nanowires (NWs) on its surface forming an efficient PdAg NWs/g-C_xN₄ Mott–Schottky heterojunction for enhancing dehydrogenation photocatalysis of FA. The boosting photocatalysis benefits from the Schiff-base bond tuning the E_g of g-C₃N₄ and strongly coupling from the heterojunction. Among the heterojunction, the Pd₅Ag₅ NWs/g-C_3.6N₄ exhibits the best dehydrogenation photocatalysis of FA [turnover frequency (TOF) = 1230 h⁻¹] under visible light (λ > 400 nm) without any additive at 25 °C, which is the best value among ever-reported ones. This work provides a new strategy to boost dehydrogenation photocatalysis of FA, which will be promising for practical application of H₂ in future energy field. Graphical abstract: [Figure not available: see fulltext.]