Boron Doping‐Induced Ultrahigh Ce ³⁺ Ratio in Amorphous CeO ₂ /GO Catalyst for Low‐Concentration CO ₂ 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mi>F</mml:mi> <mml:mi>m</mml:mi> <mml:mover><mml:mn>3</mml:mn> <mml:mo>¯</mml:mo></mml:mover> <mml:mi>m</mml:mi></mml:mrow> <mml:annotation>$Fm\bar 3m$</mml:annotation></mml:semantics> </mml:math> 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.