Pd Nanosheet-Decorated 2D/2D g-C 3 N 4 /WO 3 ·H 2 O S-Scheme Photocatalyst for High Selective Photoreduction of CO 2 to CO.

The development of the global economy in recent years, environmental problems, greenhouse effect, and so forth have been of concern for countries all over the world. The key for solving the greenhouse effect is the reduction of CO 2 . With the development of photocatalytic reduction of CO 2 , hybrid photocatalytic nanostructures composed of noble metals and plasmonic semiconductors are being widely studied. In this work, S-scheme photocatalysts with a g-C 3 N 4 /WO 3 ·H 2 O/Pd heterostructure was constructed by introducing ultrathin Pd nanosheets into the optimized 2D/2D g-C 3 N 4 /WO 3 ·H 2 O binary system. The S-scheme charge transfer generated by the matched band gap of g-C 3 N 4 and WO 3 ·H 2 O can effectually improve the electron transfer rate and the redox ability of photogenerated carriers. The introduction of Pd nanosheets can inject a large number of hot electrons into the semiconductor on the basis of the S-scheme heterojunction to participate in the reaction. The S-scheme electron transfer method is used to improve the utilization rate of thermionic electrons and achieve the effect of widening the near-infrared-light absorption area of the composite material. Moreover, the reaction was carried out in water without the addition of any sacrificial agent, which can better reflect the green environmental protection of the experiment. This investigation will promote the broad-spectrum application of new and environment-friendly thermoelectron-assisted S-scheme photocatalysts, and on this basis, the possible reaction mechanism is discussed.