Interface Engineered Bimetallic Cu2MoS4/MIL-88B(Fe, Ni) S-Scheme Nanohybrid for Photo-Assisted Green Hydrogen Generation and Oxidative Cleavage of Cinnamaldehyde to Benzaldehyde.

The production of green hydrogen and natural benzaldehyde is in high demand due to requirement of pollution-free fuel and preference of natural flavors and pharmaceutical ingredients. Herein, a Cu2MoS4/MIL-88B(Fe, Ni) binary nanohybrid is designed for high-throughput photocatalytic hydrogen evolution and natural benzaldehyde production by oxidative cleavage of cinnamaldehyde. To facilitate stimulated charge migration, Ni2+ ion is substituted in Fe3O cluster of Fe-MOF to form Fe2+/Fe3+-Ni2+/Ni3+ redox couple. The coordination environment and oxidation state of metal ions in bimetallic MOF are elucidated by EXAFS, XANES, and ESR studies. Furthermore, the texture of Cu2MoS4 is modified by acid etching to generate abundant active sites and Cu vacancies. The orbital contribution to the electronic band structure of the semiconductors is elucidated by DFT study. The Cu2MoS4/MIL-88B(Fe, Ni) nanohybrids displayed superior physicochemical and optoelectronic features compared to pristine components. Comprehensive investigation of charge transfer mechanism using Kelvin probe microscopy, femtosecond transient absorption spectroscopy, and in situ XPS revealed S-scheme mechanism. The optimized nanohybrid showed 8225 µmol g-1 h-1 hydrogen production with 14.7% light conversion efficiency. Additionally, oxidative cleavage of cinnamaldehyde to benzaldehyde is achieved at a rate of 2810 µmol g-1 h-1 by using dioxygen as green oxidant with 68% selectivity.