Cocatalyst Embedded Ce-BDC-CeO 2 S-Scheme Heterojunction Hollowed-Out Octahedrons With Rich Defects for Efficient CO 2 Photoreduction.

Constructing heterojunction photocatalysts with optimized architecture and components is an effective strategy for enhancing CO 2 photoreduction by promoting photogenerated carrier separation, visible light absorption, and CO 2 adsorption. Herein, defect-rich photocatalysts (Ni 2 P@Ce-BDC-CeO 2 HOOs) with S-scheme heterojunction and hollowed-out octahedral architecture are prepared by decomposing Ce-BDC octahedrons embedded with Ni 2 P nanoparticles and subsequent lactic acid etching for CO 2 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 2 molecules and gaseous products. As expected, the optimized photocatalyst exhibits excellent performance, producing CO with a yield of 61.6 µmol h -1  g -1 , 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 2 photoreduction process are detected by in situ Fourier transform infrared spectroscopy to support the proposed mechanism for CO 2 photoreduction. This work presents a synthetic strategy for excellent catalysts with potential prospects in photocatalytic applications.