Crystal defects engineering of BiOI elevated photocatalytic CO2 to C2 conversion performance

BiOI materials show significant potential for photocatalytic CO 2 reduction, but their limited CO 2 activation and poor charge carrier properties hinder conversion efficiency. In this study, we engineered BiOI-based photocatalysts with abundant crystal defects to enhance performance. X-ray diffraction (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM) revealed lattice distortions and twin crystals in BiOI-LD and BiOI-TC. Ultraviolet-visible spectroscopy, micropore and chemisorption analyses, and photoluminescence spectroscopy demonstrated that crystal defects improved light absorption, CO 2 adsorption, charge transfer efficiency, and carrier lifetime. Electron paramagnetic resonance (EPR) spectroscopy showed increased superoxide radical generation in BiOI-TC, suggesting higher reactivity. Consequently, BiOI achieved a CH 3 CH 2 OH generation rate of 6.2 µmol g −1 h −1 with 100% selectivity. Key intermediates (*CO, *COCO, *CHO, *CH 2 ) for CH 3 CH 2 OH production were identified, and C 2 H 6 formation in BiOI-LD was linked to the generation of *CH 3 .