Origin of enhanced visible-light photocatalytic activity of transition-metal (Fe, Cr and Co)-doped CeO₂: effect of 3d orbital splitting

详细信息    查看全文

• 作者：Ke Yang ; Dong-Feng Li ; Wei-Qing Huang ; Liang Xu ; Gui-Fang Huang…
• 刊名：Applied Physics A
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：123
• 期：1
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Condensed Matter Physics; Optical and Electronic Materials; Nanotechnology; Characterization and Evaluation of Materials; Surfaces and Interfaces, Thin Films; Operating Procedures, Materials Treatment
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-0630
• 卷排序：123

文摘

Enhanced visible-light photocatalytic activity of transition-metal-doped ceria (CeO₂) nanomaterials has experimentally been demonstrated, whereas there are very few reports mentioning the mechanism of this behavior. Here, we use first-principles calculations to explore the origin of enhanced photocatalytic performance of CeO₂ doped with transition metal impurities (Fe, Cr and Co). When a transition metal atom substitutes a Ce atom into CeO₂, t_2g and e_g levels of 3d orbits appear in the middle of band gap owing to the effect of cubic ligand field, and the former is higher than latter. Interestingly, t_2g subset of Fe_Ce (Co_Ce and Cr_Ce)–V_o–CeO₂ splits into two parts: one merges into the conduction band, the other as well as e_g will remain in the gap, because O vacancy defect adjacent to transition metal atom will break the symmetry of cubic ligand field. These e_g and t_2g levels in the band gap are beneficial for absorbing visible-light and enhancing quantum efficiency because of forbidden transition, which is one key factor for enhanced visible-light photocatalytic activity. The band gap narrowing also leads to a redshift of optical absorbance and high photoactivity. These findings can rationalize the available experimental results and provide some new insights for designing CeO₂-based photocatalysts with high photocatalytic performance.