Liu Conghui, Li Rongtan, Feng Xiaohui, Sun Yuting, Fan Yamei, Li Jiaxin, Fu Qiang
School of Chemistry, Dalian University of Technology Dalian 116024 China.
State Key Laboratory of Catalysis, Chinese Academy of Sciences, Dalian Institute of Chemical Physics Dalian 116023 China
Chem Sci. 2025 Jun 20. doi: 10.1039/d5sc01637a.
Water has a profound effect on the surface structure and catalytic performance of numerous heterogeneous catalysts. Understanding the mechanism of structural evolution in water-containing reaction atmospheres is essential for the rational design of catalysts with enhanced catalytic efficiency and stability. In this work, we have observed spontaneous redispersion of physically mixed ZnO particles onto TiO surfaces in water-containing environments at room temperature. Water vapor at a pressure greater than 3.2 kPa is a prerequisite for the efficient ZnO redispersion, in which a water adlayer with a thickness of about three monolayers forms on the TiO surface. Raising the sample temperature to 50 °C or rendering the TiO surface hydrophobic prevents the formation of the water adlayer and thereby inhibits the ZnO redispersion. Solid-state nuclear magnetic resonance spectroscopy and spectroscopic analyses confirm that the surface water adlayer serves as a migration channel for ZnO species. Moreover, ZnO achieves more rapid and complete redispersion in a liquid water environment. This structural regulation strategy increases the number of exposed active sites in the ZnO-TiO catalyst, leading to enhanced catalytic activity in propane dehydrogenation.
水对众多非均相催化剂的表面结构和催化性能有着深远影响。了解在含水反应气氛中结构演变的机制对于合理设计具有更高催化效率和稳定性的催化剂至关重要。在这项工作中，我们观察到在室温下，物理混合的ZnO颗粒在含水环境中会自发地再分散到TiO表面上。压力大于3.2 kPa的水蒸气是ZnO有效再分散的先决条件，在此过程中，TiO表面会形成一层厚度约为三个单分子层的水吸附层。将样品温度升高到50°C或使TiO表面疏水会阻止水吸附层的形成，从而抑制ZnO的再分散。固态核磁共振光谱和光谱分析证实，表面水吸附层充当了ZnO物种的迁移通道。此外，ZnO在液态水环境中实现了更快且更完全的再分散。这种结构调控策略增加了ZnO-TiO催化剂中暴露的活性位点数量，从而提高了丙烷脱氢反应中的催化活性。
