Cocatalyst Embedded Ce-BDC-CeO S-Scheme Heterojunction Hollowed-Out Octahedrons With Rich Defects for Efficient CO Photoreduction.

Constructing heterojunction photocatalysts with optimized architecture and components is an effective strategy for enhancing CO photoreduction by promoting photogenerated carrier separation, visible light absorption, and CO adsorption. Herein, defect-rich photocatalysts (NiP@Ce-BDC-CeO HOOs) with S-scheme heterojunction and hollowed-out octahedral architecture are prepared by decomposing Ce-BDC octahedrons embedded with NiP nanoparticles and subsequent lactic acid etching for CO photoreduction. The hollowed-out octahedral architecture with multistage pores (micropores, mesopores, and macropores) and oxygen vacancy defects are simultaneously produced during the preparation process. The S-scheme heterojunction boosts the quick transfer and separation of photoinduced charges. The formed hollowed-out multi-stage pore structure is favorable for the adsorption and diffusion of CO molecules and gaseous products. As expected, the optimized photocatalyst exhibits excellent performance, producing CO with a yield of 61.6 µmol h g, which is four times higher than that of the original Ce-BDC octahedrons. The X-ray photoelectron spectroscopy, scanning Kelvin probe, and electron spin resonance spectroscopy characterizations confirm the S-schematic charge-transfer route. The key intermediate species during the CO photoreduction process are detected by in situ Fourier transform infrared spectroscopy to support the proposed mechanism for CO photoreduction. This work presents a synthetic strategy for excellent catalysts with potential prospects in photocatalytic applications.