The development of efficient catalytic structure for selective cleavage of thermodynamically stable C–C and C–H bonds is a challenging research field for renewable polyol oxidation, which is largely unexplored. Herein, we constructed an unsaturated coordination Fe–O_v–Ti_5c structure for glycerol oxidation to glycolic acid via tuning the crystal forms of TiO₂. Compared with Fe/TiO₂-rutile dominated with Fe–O–Ti_6c sites, Fe/TiO₂-anatase exhibits rich Fe–O_v–Ti_5c sites with strong electron transfer and abundant surface oxygen vacancies originating from the chemical nature of the (101) facet. Specifically, the synergistic effect between unsaturated Ti_5c sites and Fe_5c (five-coordination) sites promotes the adsorption of glycerol via strong electron transfer from the TiO₂-anatase (101) to Fe species. Moreover, the abundant surface oxygen vacancies enhance the activation of the C–H bond and the cleavage of the C–C bond over the interfacial unsaturated coordination Fe–O_v–Ti_5c structure. Consequently, the Fe/TiO₂-anatase catalyst exhibits record high catalytic activity (TOF: 54.4 h^–1) and glycolic acid selectivity (59.1%). The outcome of this work may provide some meaningful suggestions for the rational design of catalysts in biopolyol oxidation systems.

中文翻译：

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具有增强的 C-H 和 C-C 键活化能力的不饱和 Fe-Ov-Ti5c 结构用于甘油选择性氧化为乙醇酸


开发用于选择性裂解热力学稳定的 C-C 和 C-H 键的高效催化结构是可再生多元醇氧化的一个具有挑战性的研究领域，该领域在很大程度上尚未得到探索。在此，我们通过调整 TiO ₂ 的晶型，构建了不饱和配位 Fe-O _v -Ti _5c 结构，用于甘油氧化为乙醇酸。与 Fe/TiO ₂ -金红石以 Fe-O-Ti _6c 位点为主相比，Fe/TiO ₂ -锐钛矿表现出丰富的 Fe-O _v –Ti _5c 位点具有强电子转移和丰富的表面氧空位，这源于（101）面的化学性质。具体而言，不饱和Ti _5c 位点和Fe _5c （五配位）位点之间的协同效应通过TiO ₂ 的强电子转移促进甘油的吸附-锐钛矿 (101) 至 Fe 物种。此外，丰富的表面氧空位增强了界面不饱和配位Fe-O _v -Ti _5c 结构上C-H键的活化和C-C键的断裂。 。因此，Fe/TiO ₂ -锐钛矿催化剂表现出创纪录的高催化活性（TOF：54.4 h ^–1 ）和乙醇酸选择性（59.1％）。这项工作的结果可能为生物多元醇氧化系统中催化剂的合理设计提供一些有意义的建议。