Wu Longxia, Wu Zongfang, Li Fei, Wang Zhengming, Zhang Zhen, Gong Xue-Qing, Huang Weixin
Key Laboratory of Precision and Intelligent Chemistry, iChEM, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, P.R. China.
Core Facility of Wuhan University, Wuhan University, Wuhan 430072, P. R. China.
J Phys Chem Lett. 2024 Aug 22;15(33):8481-8486. doi: 10.1021/acs.jpclett.4c02137. Epub 2024 Aug 12.
Photochemistry of methanol on TiO surfaces is of great importance both fundamentally and industrially. Methanol was previously reported only to occur photogenerated hole-participating oxidation reactions on TiO surfaces. Herein, we report that, upon UV light illumination, the methoxy species formed by methanol dissociation at the 5-fold coordinated Ti sites (CHO(a)) of a reconstructed rutile TiO(001)-(1 × 1) surface also undergoes the C-O bond cleavage into methyl fragments mediated by photogenerated electrons, in addition to the well-established photogenerated hole-participating oxidation reactions. Upon subsequent heating, the resulting methyl species undergoes hydrogenation and coupling reactions into methane and ethane, respectively. Accompanying theoretical calculations showed that the lowest unoccupied molecular orbital (LUMO) of CHO(a) is localized almost at the conduction band minimum of the CHO-adsorbed reconstructed rutile TiO(001)-(1 × 1) surface, indicating the likely TiO → CHO(a) interfacial photoexcited-electron transfer. These results greatly broaden the photochemistry of methanol on TiO surfaces and demonstrate a photocatalytic methanol-to-hydrocarbon reaction route.
甲醇在TiO表面的光化学在基础研究和工业应用方面都具有重要意义。此前报道甲醇在TiO表面仅发生光生空穴参与的氧化反应。在此，我们报道，在紫外光照射下，在重构的金红石TiO(001)-(1×1)表面五重配位Ti位点（CHO(a)）处由甲醇解离形成的甲氧基物种，除了既定的光生空穴参与的氧化反应外，还会在光生电子介导下发生C-O键断裂生成甲基片段。随后加热时，生成的甲基物种分别发生氢化反应和偶联反应生成甲烷和乙烷。伴随的理论计算表明，CHO(a)的最低未占据分子轨道（LUMO）几乎定域在CHO吸附的重构金红石TiO(001)-(1×1)表面的导带最小值处，表明可能存在TiO→CHO(a)界面光激发电子转移。这些结果极大地拓宽了甲醇在TiO表面的光化学，并展示了一条光催化甲醇制烃的反应路线。
