Directing charge transfer in a chemical-bonded Ni/Cd0.7Mn0.3S Schottky heterojunction for selective photocatalytic oxidation of benzyl alcohol structural organic platform molecules coupled with hydrogen evolution reaction

Solar-energy-driven half-reactions coupling is a vital photocatalysis strategy to simultaneously realize low-value organic platform molecules value-added conversion and hydrogen production. It is essential to design photocatalyst with appropriate band structures and efficient spatial separation of photogenerated hole/electron pairs (h+/e-) to drive reduction/oxidation half-reactions, respectively. Herein, chemical-bonded Ni/Cd0.7Mn0.3S Schottky junction was constructed via hydrothermal-chemical reduction method for sunlight-driven catalytic selective dehydrogenation oxidization of benzyl alcohol (BA) coupling with hydrogen evolution reaction (HER). The optimal 8% Ni/Cd0.7Mn0.3S exhibited excellent BA conversion rate (77%), benzaldehyde (BAD) yield (2.88 mmol·g−1·h−1), selectivity (99%) and HER activity (2.94 mmol·g−1·h−1). The selective oxidation of BA and its para-substituents (-CH3, -OCH3, -Br, -NO2) proceeded a carbon-centred radical mechanism via the cleavage of αC-H bond. Furthermore, the Ni/Cd0.7Mn0.3S exhibits excellent selective oxidation of the other organic platform molecules with benzyl alcohol structure, such as 5-hydroxymethylfurfural (HMF) and vanillyl alcohol (VAL), etc, validating that the chemical-bonded Ni/Cd0.7Mn0.3S possess the excellent performance in αC-H bond activation of benzyl alcohol structure unit. By combining experiment and DFT calculation results, the Ni-S bond formed at Ni/Cd0.7Mn0.3S interface can accelerate the directing charge transfer, thus boosting the organic platform molecules selective oxidation coupling with HER.