The organic-inorganic S-scheme heterojunction with enhanced charge separation simultaneously catalyze the production of hydrogen and imine

Photocatalytic hydrogen production coupled with value-added chemical synthesis has attracted extensive research interests as a promising route to realize efficient conversion of solar energy to chemical energy. However, the rapid charge recombination hinders the improvement of conversion efficiency. Herein, a pyrene-based conjugated polymer (PyDF)/Mn 0.2 Cd 0.8 S (MCS) organic-inorganic S-scheme heterojunction photocatalyst (PMCS) was reported. The incorporation of large delocalized π -conjugation system and formation of the S-scheme heterojunction significantly enhanced the charge separation and transfer. As a result, the optimal PMCS 0.5 composite exhibited a hydrogen evolution rate of 16.3 mmol h –1 g –1 with ascorbic acid as sacrificial agent. In the coupled system for benzylamine (BA) oxidation and hydrogen production, it delivered a hydrogen evolution rate of 3.72 mmol h –1 g –1 , with nearly 100% conversion of 358.8 μmol BA to N -benzylidene benzylamine (NBBA) within 4 h. To elucidate the charge transfer mechanism within the S-scheme heterojunction, density functional theory calculations, in-situ X-ray photoelectron spectroscopy, and in-situ irradiated Kelvin probe force microscopy were conducted. In addition, in-situ diffuse reflectance infrared Fourier transform spectroscopy was employed to monitor the stepwise transformation of amines to imines during the photocatalytic process. This work offers a promising approach for bifunctional photocatalyst design toward simultaneous energy conversion and green synthesis.