Boron Doping-Induced Ultrahigh Ce3+ Ratio in Amorphous CeO2/GO Catalyst for Low-Concentration CO2 Photoreduction

Abstract

Direct utilization of diluted CO2 enables sustainable CO2 conversion into valuable products, with reduced CeO2 emerging as an attractive candidate due to its exceptional redox flexibility. The catalytic efficacy of CeO2 is intimately tied to the electronic structure of 4f, yet the persistent challenge lies in maintaining a high and stable concentration of Ce3+. In this study, we propose a symmetry-breaking-induced amorphization strategy to achieve an exceptionally high Ce3+ ratio by B doping, which facilitates the reduction of Ce4+ to Ce3+ in amorphous CeO2. First-principles calculations and infrared spectroscopy reveal that B doping with three excess electrons induces the formation of planar triangular B-O₃ units by disrupting the original high-symmetry structure of CeO2, facilitating the spontaneous transition to the amorphous phase. Electronic structure analysis confirms that even a modest 7.5% B doping can significantly elevate the Ce3+ ratio to 85.7%. The resulting amorphous B-doped CeO2/GO shows a remarkable CO2-to-CO conversion rate of 249.33 µmol g-1 h-1(under 15% CO2) and 103.4 µmol g-1 h-1(under 1% CO2), with 100% selectivity in both cases. This performance highlights how amorphization stabilizes defect states, making amorphous CeO2/GO with high Ce3+ an effective material for CO2 photoreduction and addressing key challenges in CO2 capture and utilization.