Electron beam- induced defect engineering construction in MIL-68(In) for enhanced CO₂ photoreduction: unravelling...

Photocatalytic CO₂ reduction is a promising strategy to address both environmental issues and energy crisis. Defect engineering offers great potential for improving the photocatalytic performance. Herein, we report an innovative approach to introduce defects in MIL-68(In) via electron beam irradiation for the photoreduction of CO₂ into CH₄. The irradiated X-MIL-68(In) (X mean the irradiation dose) retained the crystal structure and morphology of pristine MIL-68(In), while generating novel organic framework defects. These defects significantly improved the CO₂ photoreduction activity, with 300-MIL-68(In) achieving the highest CH₄ rate of 87.5 μmol g^-1 h^-1 and a CH₄ selectivity of 74.8 %. Comprehensive ex situ and in situ characterizations, combined with DFT calculations, demonstrated that defects formation in 300-MIL-68(In) accelerated the separation and transfer of photoexcited carriers, thereby driving its superior photocatalytic performance. Furthermore, in situ DRIFTS along with DFT calculations confirmed that ^⁎COOH, ^⁎CHO and ^⁎CH₂O were key intermediates during CO₂ reduction process. This work highlights electron beam irradiation as an effective strategy for defect engineering, offering new opportunities for tuning the performance of photocatalysts.