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

• Photoreduction CO 2 to syngas evolution could be achieved by CoMgAl-LDH. • The highl high dispersion of Co and hydroxyl defects contributed the photoactivity. • CoMgAl-LDH exhibited excellent performance under high wavelength of 650 nm. The conversion of solar energy to chemical fuels by CO 2 photoreduction reaction (CO 2 PR) 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 CO 2 photocatalytic reduction system to syngas by introducing Co into MgAl-layered double hydroxide (CoMgAl-LDH) nanosheets in conjunction with Ru(bpy) 3 ]Cl 2 ·6H 2 O as photosensitizer, in which [Ru(bpy) 3 ]Cl 2 ·6H 2 O could be activated to generate photogenerated electrons which further transfer to surface of CoMgAl-LDH for CO 2 reduction. Under irradiation >400 nm, the CoMgAl-LDH nanosheets showed excellent CO 2 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 CO 2 PR to syngas under wavelength irradiation up to 650 nm.