Highly efficient simultaneous hydrogen evolution and benzaldehyde production using cadmium sulfide nanorods decorated with small cobalt nanoparticles under visible light

Abstract

Photocatalytic hydrogen evolution coupled with selective oxidation to produce fine chemicals under mild conditions is a promising strategy for green synthesis of both fuel carriers and useful materials. Herein, we report a highly efficient catalyst, created by in-situ anchoring cobalt nanoparticles onto cadmium sulfide nanorods, for simultaneous hydrogen evolution and benzaldehyde production from photocatalytic dehydrogenation of benzyl alcohol under visible light. Two half reactions, hydrogen evolution and benzaldehyde production, are well coupled as the reductive side and oxidative side, respectively. The system can produces hydrogen and benzaldehyde with high selectivity and efficiency. The optimal selectivity for benzaldehyde production is ∼94.4%. Mechanism studies indicate that the carbon-centered radical is the key intermediate during the oxidation of benzyl alcohol and plays a very important role on the selectivity for benzaldehyde production. Under optimal conditions, the rate of hydrogen evolution in the present noble-metal-free system is ∼848 µmol h−1 and an apparent quantum yield of 63.2% (λ = 420 ± 5 nm) is achieved. To the best of our knowledge, this is the highest value ever reported for hydrogen evolution from photocatalytic dehydrogenation of benzyl alcohol under visible light.