Tuning the selectivity of photoreduction of CO2 to syngas over Pd/layered double hydroxide nanosheets under visible light up to 600 nm

Photocatalytic reduction of CO2 with H2O to syngas is an effective way for producing high value-added chemical feedstocks such as methanol and light olefins in industry. Nevertheless, the precise control of CO/H-2 ratio from photocatalytic CO2 reduction reaction still poses a great challenge for the further application. Herein, we prepared a series of highly efficient heterostructure based on highly dispersed palladium supported on ultrathin CoAl-layered double hydroxide (LDH). In conjunction with a Ru-complex sensitizer, the molar ratios of CO/H-2 can be tuned from 1:0.74 to 1:3 under visible-light irradiation (lambda > 400 nm). More interestingly, the syngas can be obtained under light irradiation at lambda > 600 nm. Structure characterization and density functional theory calculations revealed that the remarkable catalytic activity can be due to the supported palladium, which improved the charge transfer efficiency. Meanwhile, more H atoms were used to generate H-2 on the supported palladium for further tunable CO/H-2 ratio. This work demonstrates a new strategy for harnessing abundant solar-energy to produce syngas from a CO2 feedstock. (C) 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.