650 nm-driven syngas evolution from photocatalytic CO2 reduction over Co-containing ternary layered double hydroxide nanosheets

Abstract

The conversion of solar energy to chemical fuels by CO2 photoreduction reaction (CO2PR) is a promising pathway to alleviate rapid energy consumption crisis. Nevertheless, only a few systems have been reported so far by applying solar energy in visible light region in particular high wavelength (such as λ ≥ 650 nm). Herein, we report an efficient 650 nm-induced CO2 photocatalytic reduction system to syngas by introducing Co into MgAl-layered double hydroxide (CoMgAl-LDH) nanosheets in conjunction with Ru(bpy)3]Cl2·6H2O as photosensitizer, in which [Ru(bpy)3]Cl2·6H2O could be activated to generate photogenerated electrons which further transfer to surface of CoMgAl-LDH for CO2 reduction. Under irradiation >400 nm, the CoMgAl-LDH nanosheets showed excellent CO2 conversion with TOF of 11.57 h−1, 3 times higher than that of CoAl-LDH. Most importantly, up to monochromatic irradiation wavelength at 650 nm, the CoMgAl-LDH nanosheets still displayed optimized syngas evolution rate, with CO rate of 0.35 μmol·h−1 with quantum yield of 0.86%. Furthermore, as evidenced by X-ray absorption fine structure spectroscopy and high-resolution synchrotron X-ray powder diffraction, the proper introduction of Co promoted its dispersion on the laminate of LDH. The suitable dispersion of Co active sites into LDH nanosheets facilitates the transportation of photo-generated electrons to further promote catalytic activity for reaction. This work paves a potential way for CO2PR to syngas under wavelength irradiation up to 650 nm.