Thread Content
Experimental determination of the intrinsic energy levels of single-atom catalysts and high-throughput screening achieved by our institute – Publication date: 2025-04-03. Recently, the team led by Academician Zhang Tao and Associate Researcher Yang Bing from the Institute’s Catalysis and New Materials Research Center (Group 1500), in collaboration with the teams of Professors Lu Junling and Wu Xiaojun from the University of Science and Technology of China, have made significant progress in the field of single-atom catalysis. “Since the concept of \"single-atom catalysis\" was first proposed in 2011 by Zhang Tao’s team and others, it has rapidly become a hot research topic and frontier in the field of catalysis worldwide. However, at present, there is still a lack of a general descriptor and unified theory that can quantitatively describe the structure-performance relationship of single-atom catalysts, making it impossible to interpret the essence of single-atom catalysis. Due to the quasi-homogeneous catalytic properties of single-atom catalysts, they can theoretically be described using frontier molecular orbital theory. However, experimental measurement of single-atom eigenenergies still faces huge challenges. Environmental sensitivity makes single-atom catalysts prone to oxidation when exposed to air, resulting in difficulties in measuring their intrinsic properties. In recent years, to address this challenge, Zhang Tao’s team has developed an \"visualization + quantification\" in-situ characterization method that combines in-situ microscopy with spectroscopic techniques, enabling quantitative analysis of the local and dynamic properties of single-atom catalysts (J. Am. Chem. Soc., 2023) ； Chem，2022 ； Nature Commun., 2024 ； ACS Catal., 2023). Building on this foundation, this work innovatively introduces Frontier Molecular Orbital theory (FMO) into the design of single-atom catalysts. By utilizing in-situ micro-photoelectron spectroscopy techniques, experimental measurements were carried out on the intrinsic structures, intrinsic electronic states, and intrinsic energy levels of a series of Pd1/MOx (where M = Zn, Ti, Ga, Co, Ni, etc.) single-atom catalysts supported on semiconductor oxides, thereby revealing the quantitative relationship between the orbital level coupling between the single atoms and the support and reaction activity. By utilizing the quantum size effect and adjusting the size of the MOx oxide carriers, researchers were able to precisely control the electronic properties of Pd single atoms as well as their performance in the selective hydrogenation of acetylene. Quantitative analysis of the structure-activity relationship shows that, on oxide supports of the same type, there is a good correlation between the valence state of Pd atoms and their activity (TOF), but no universal pattern can be observed across different oxide supports. In contrast, by utilizing quasi-in-situ UV photoelectron spectroscopy, researchers were able to accurately measure the LUMO orbital energy levels of different oxide carriers and relate them to reaction activity, obtaining a consistent linear relationship across 34 Pd1/MOx catalysts (including 14 n-type/p-type semiconductor oxide carriers). Further calculations using molecular orbital theory show that the upward shift in the LUMO energy level of the oxide carrier enhances orbital hybridization between Pd atoms and the carrier. This not only significantly improves the stability of the single atoms but also strengthens the orbital coupling between the hybridized Pd single-atom active centers and the reaction molecules, thereby increasing the reactivity. Furthermore, through structure-activity relationship screening, researchers found that Pd1/ZnO-1.9nm exhibits the best performance in acetylene hydrogenation reactions, outperforming existing Pd-based catalysts significantly in terms of activity, selectivity, and stability. This work achieves a quantitative analysis of the intrinsic energy levels of single-atom catalysts. For the first time, it proposes the LUMO orbital energy level of the support as a universal descriptor to enable high-throughput screening of single-atom catalysts, providing experimental evidence for interpreting the nature of single-atom catalysis through molecular orbital theory. The relevant findings, titled “Metal–support frontier orbital interactions in single-atom catalysis”, were recently published in Nature. The co-first authors of this achievement are Dr. Xi Xianxian and Dr. Wen Zhilin from the University of Science and Technology of China, as well as Assistant Researcher Gu Qingqing from our institute. This research was funded by the **Key Research and Development Program**, the National Natural Science Foundation of China’s Basic Science Center for \"Single-Atom Catalysis\" project, as well as the Youth Team program in the field of basic research at the Chinese Academy of Sciences.