Efficient photocatalytic dehydrogenation and synergistic selective oxidation of benzyl alcohol to benzaldehyde for Zn0.5Cd0.5S co-modified with MoS2 nanoflowers and g-C3N4 nanosheets

The Zn0.5Cd0.5S solid solution co-modified with MoS2 nanoflowers and g-C3N4 nanosheets (C3N4/MoS2/Zn0.5Cd0.5S) was successfully synthesized with highly efficient photocatalytic dehydrogenation and synergistic selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). The reaction selectivity is explored by detecting all substances of solution after reaction for the Zn0.5Cd0.5S and C3N4/Zn0.5Cd0.5S using gas chromatography-mass spectrometry (GCMS) test, and the mechanism for highly efficient photocatalytic dehydrogenation and synergistic selective oxidation of BA to BAD was systematically investigated by electron paramagnetic resonance (EPR) and first-principles density-functional theory (DFT) calculations. The research work would provide a feasible, sustainable, economical, and potential technique for the highly efficient dehydrogenation and synergistic selection of benzyl alcohol based on photocatalysis which excludes the usage of noble metals and sacrificial reagents. [Display omitted] •Zn0.5Cd0.5S solid solution co-modified by MoS2 nanoflowers & g-C3N4 nanosheets.•Highly efficient photocatalytic dehydrogenation by C3N4/MoS2/Zn0.5Cd0.5S.•Synergistic selective almost 100% oxidation benzyl alcohol to benzaldehyde.•PBN-carbon centered radicals induced are the key intermediates for dehydrogenation.•Mechanism for enhanced dehydrogenation & selective oxidation of BA were proposed. Zn0.5Cd0.5S solid solution co-modified by MoS2 nanoflowers and g-C3N4 nanosheets (C3N4/MoS2/Zn0.5Cd0.5S) was synthesized with highly efficient photocatalytic dehydrogenation and synergistic selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). The photocatalytic dehydrogenation rate and BAD yield are 1.7 mmol·g−1·h−1 and 35.8% for C3N4/MoS2/Zn0.5Cd0.5S, and selective oxidation to BAD is almost 100%. Reaction selectivity was explored by detecting all the substances of the solution after reaction for Zn0.5Cd0.5S and C3N4/Zn0.5Cd0.5S using gas chromatography-mass spectrometry (GCMS), and analysis results indicated that BA was converted to other substances because of the insufficient hole oxidation capacity of the samples. The mechanism for highly efficient photocatalytic dehydrogenation and synergistic selective oxidation of BA to BAD was systematically investigated by electron paramagnetic resonance (EPR) and first-principle density-functional theory calculations. The EPR spectra of the phenyl-N-tert-butyl-nitrone (PBN)-carbon centered radical indicated that ·C induc