Gong Dongkun, Wu Yingjie, Jiang Hao, Li Chunzhong, Hu Yanjie
Key Laboratory for Ultrafine Materials of Ministry of Education, Shanghai Environmental Friendly Materials Technical Service Platform, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China.
Langmuir. 2024 Apr 9;40(14):7492-7501. doi: 10.1021/acs.langmuir.3c04020. Epub 2024 Mar 26.
The important concept of confined synthesis is considered a promising strategy for the design and synthesis of definable nanostructured materials with controllable compositions and specific morphology, such as highly loaded single-atom catalysts capable of providing abundant active sites for photocatalytic reactions. In recent years, researchers have been working on developing new confined reaction systems and searching for new confined spaces. Here, we present for the first time the concept of a bubble liquid film as a novel confined space. The liquid film has a typical sandwich structure consisting of a water layer, sandwiched between the upper and lower surfactant layers, with the thickness of the intermediate water layer at the micro- and nanometer scales, which can serve as a good confinement. Based on the above understanding and combined with the photodeposition method, we successfully confined synthesized Ag/TiO, Au/TiO, and Pd/TiO photocatalysts in liquid film. By HAADF-STEM, it can be seen that the noble metal morphologies are all nanoclusters of about 1 nm and are highly uniformly dispersed on the TiO surface. Compared with photodeposition in solution, we believe that the surfactant molecular layer restricts a limited amount of precursor to the liquid film, avoiding the accumulation of noble metals and the formation of large particle size nanoparticles. The liquid film, meanwhile, restricts the migration path of noble metal precursors, allowing for thorough in situ photodeposition and enables the complete and uniform dispersion of noble metal precursors, greatly reducing the photodeposition time. The uniform loading of the three noble metals proved the universality of the method, and the catalysts showed high activity for photocatalytic CO reduction. The rates of reduction of CO to CO over the Ag/TiO photocatalytic reached 230 μmol g h.This study provides a new idea for the expansion of the confined reaction system and a reference for the study of liquid film as the confined space.
受限合成的重要概念被认为是一种很有前景的策略，用于设计和合成具有可控组成和特定形态的可定义纳米结构材料，例如能够为光催化反应提供丰富活性位点的高负载单原子催化剂。近年来，研究人员一直在致力于开发新的受限反应体系并寻找新的受限空间。在此，我们首次提出气泡液膜作为一种新型受限空间的概念。该液膜具有典型的三明治结构，由夹在上、下表面活性剂层之间的水层组成，中间水层的厚度处于微米和纳米尺度，可作为良好的限制环境。基于上述认识并结合光沉积方法，我们成功地在液膜中受限合成了Ag/TiO、Au/TiO和Pd/TiO光催化剂。通过高角度环形暗场扫描透射电子显微镜（HAADF-STEM）可以看出，贵金属形态均为约1nm的纳米团簇，并且高度均匀地分散在TiO表面。与溶液中的光沉积相比，我们认为表面活性剂分子层将有限量的前驱体限制在液膜中，避免了贵金属的积累和大粒径纳米颗粒的形成。同时，液膜限制了贵金属前驱体的迁移路径，使得原位光沉积得以充分进行，并使贵金属前驱体能够完全且均匀地分散，大大缩短了光沉积时间。三种贵金属的均匀负载证明了该方法的通用性，并且这些催化剂对光催化CO还原表现出高活性。在Ag/TiO光催化作用下，CO还原为CO的速率达到230 μmol g h 。本研究为扩展受限反应体系提供了新思路，并为将液膜作为受限空间的研究提供了参考。
