Gao Meiqi, Ma Junhao, Li Yanyan, Lin Ximao, Wu Limin, Zou Yidong, Deng Yonghui
Institute of Chemistry, Henan Academy of Sciences, Zhengzhou 450000, China.
Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, iChEM, Fudan University, Shanghai 200433, China.
ACS Appl Mater Interfaces. 2024 Apr 10;16(14):17563-17573. doi: 10.1021/acsami.4c00510. Epub 2024 Mar 29.
Hydrogen generation is one of the crucial technologies to realize sustainable energy development, and the design of advanced catalysts with efficient interfacial sites and fast mass transfer is significant for hydrogen evolution. Herein, an coassembly strategy was proposed to engineer a cerium-doped ordered mesoporous titanium oxide (mpCe/TiO), of which the abundant oxygen vacancies (O) and highly exposed active pore walls contribute to good stability of ultrasmall Pt nanoclusters (NCs, ∼ 1.0 nm in diameter) anchored in the uniform mesopores (. 20 nm). Consequently, the tailored mpCe/TiO with 0.5 mol % Ce-doping-supported Pt NCs (Pt-mpCe/TiO-0.5) exhibits superior H evolution performance toward the water-gas shift reaction with a 0.73 mol·s·mol H evolution rate at 200 °C, which is almost 6-fold higher than the Pt-mpTiO (0.13 mol·s·mol H). Density functional theory calculations confirm that the structure of Ce-doped TiO with Ce coordinated to six O atoms by substituting Ti atoms is thermodynamically favorable without the deformation of Ti-O bonds. The O generated by the six O atom-coordinated Ce doping is highly active for HO dissociation with an energy barrier of 2.18 eV, which is obviously lower than the 2.37 eV for the control TiO. In comparison with TiO, the resultant Ce/TiO support acts as a superior electron acceptor for Pt NCs and causes electron deficiency at the Pt/support interface with a 0.17 eV downshift of the Pt -band center, showing extremely obvious electronic metal-support interaction (EMSI). As a result, abundant and hyperactive Ti-O(-Ce)-Pt interfacial sites are formed to significantly promote the generation of CO and H evolution. In addition, the stronger EMSI between Pt NCs and mpCe/TiO-0.5 than that between Pt and mpTiO contributes to the superior self-enhanced catalytic performance during the cyclic test, where the CO conversion at 200 °C increases from 72% for the fresh catalyst to 99% for the used one. These findings reveal the subtle relationship between the mesoporous metal oxide-metal composite catalysts with unique chemical microenvironments and their catalytic performance, which is expected to inspire the design of efficient heterogeneous catalysts.
氢气生成是实现可持续能源发展的关键技术之一，设计具有高效界面位点和快速传质的先进催化剂对于析氢至关重要。在此，我们提出了一种共组装策略来制备铈掺杂的有序介孔二氧化钛（mpCe/TiO），其丰富的氧空位（O）和高度暴露的活性孔壁有助于锚定在均匀介孔（. 20 nm）中的超小铂纳米团簇（NCs，直径约1.0 nm）具有良好的稳定性。因此，掺杂0.5 mol%铈的定制mpCe/TiO负载的铂纳米团簇（Pt-mpCe/TiO-0.5）在水煤气变换反应中表现出优异的析氢性能，在200°C时析氢速率为0.73 mol·s·mol，几乎是Pt-mpTiO（0.13 mol·s·mol H）的6倍。密度泛函理论计算证实，通过取代Ti原子使Ce与六个O原子配位的Ce掺杂TiO结构在热力学上是有利的，且Ti-O键无变形。由六个O原子配位的Ce掺杂产生的O对H₂O解离具有高活性，能垒为2.18 eV，明显低于对照TiO的2.37 eV。与TiO相比，所得的Ce/TiO载体作为铂纳米团簇的优良电子受体，导致Pt/载体界面处电子缺乏，Pt能带中心下移0.17 eV，显示出极其明显的电子-金属-载体相互作用（EMSI）。结果，形成了丰富且高活性的Ti-O(-Ce)-Pt界面位点，显著促进了CO的生成和析氢。此外，Pt纳米团簇与mpCe/TiO-0.5之间的EMSI比Pt与mpTiO之间的更强，这有助于在循环测试中具有优异的自增强催化性能，其中200°C时的CO转化率从新鲜催化剂的72%提高到使用后催化剂的99%。这些发现揭示了具有独特化学微环境的介孔金属氧化物-金属复合催化剂与其催化性能之间的微妙关系，有望激发高效多相催化剂的设计。
