Artificial Photoenzymatic Reduction of Carbon Dioxide to Methanol by Using Electron Mediator and Co-factorAssembled ZnIn2 S4 Nanoflowers.

Abstract

Increased absorption of visible light, low electron-hole recombination, and fast electron transfer are the major objectives for highly effective photocatalysts in biocatalytic artificial photosynthetic systems. In this study, a polydopamine (PDA) layer containing electron mediator, [M], and NAD+ cofactor was assembled on the outer surface of ZnIn2 S4 nanoflower, and the as-prepared nanoparticle, ZnIn2 S4 /PDA@poly/[M]/NAD+ , was used for photoenzymatic methanol production from CO2 . Because of effective capturing of visible light, reduced distance of electron transfer, and elimination of electron-holes recombination, a high NADH regeneration of 80.7±1.43 % could be obtained using the novel ZnIn2 S4 /PDA@poly/[M]/NAD+ . In the artificial photosynthesis system, a maximum methanol production of 116.7±11.8 μm was obtained. The enzymes and nanoparticles in the hybrid bio-photocatalysis system could be easily recovered using the ultrafiltration membrane at the bottom of the photoreactor. This is due to the successful immobilization of the small blocks including the electron mediator and cofactor on the surface of the photocatalyst. The ZnIn2 S4 /PDA@poly/[M]/NAD+ photocatalyst exhibited good stability and recyclability for methanol production. The novel concept presented in this study shows great promise for other sustainable chemical productions through artificial photoenzymatic catalysis.