The reporter learned from the University of Science and Technology of China on March 4 that recently, the team of Professor Zeng Jie and Professor Wang Zhengfei of the University of Science and Technology of China worked together to propose a new concept of topological quantum catalysis. Through ingenious design, the topological quantum state control scheme is used in catalytic experiments, which provides conclusive experimental evidence for revealing the "switch" effect of topological surface states in catalytic reactions. The results were recently published in the Journal of the American Chemical Society.
In heterogeneous catalysis, reactant adsorption, electron transfer, and intermediate evolution are highly sensitive to the surface environment of the catalyst. The topological surface state of the topological material is protected by symmetry and is not affected by local disturbances. Therefore, topological materials are an ideal platform for studying the effects of surface electronic states in catalytic reactions.
In this work, the researchers selected the room-temperature topological material bismuth selenide as the research object, and designed two sets of control experiments** The topological surface state "switch" effect in the electrocatalytic reaction: by reducing the thickness of bismuth selenide, the topological surface state can be eliminated with the help of the quantum confinement effect without changing the surface structure of the catalyst; The magnetic field of bismuth selenide with topological surface state is strengthened, and the Zeeman effect and orbital effect caused by the magnetic field are used to break the time reversal symmetry, and then the topological surface state is eliminated.
Theoretical studies have found that bismuth selenide with topological surface state can weaken the adsorption of key intermediates and significantly regulate the interface behavior of key intermediates. According to the structural properties of bismuth selenide, the researchers constructed bismuth selenide model catalysts with layer thicknesses of six nanometers and two nanometers, respectively. Angle-resolved photoelectron spectroscopy was used to confirm the existence of topological surface states of six-nanometer bismuth selenide and the absence of topological surface states of two-nanometer bismuth selenide. Electrocatalytic experimental studies have shown that the electrocatalytic reduction of carbon dioxide by six-nanometer bismuth selenide mainly forms liquid products, while two-nanometer bismuth selenide easily produces gaseous products. When six-nanometer bismuth selenide electrocatalyzes carbon dioxide reduction in a strong magnetic field, its catalytic performance gradually approaches that of two-nanometer bismuth selenide with the change of magnetic field strength. Density functional theory studies have found that bismuth selenide with topological surface state can increase the rapid control step reaction barrier for the formation of formic acid and oxalic acid and increase the rapid control step reaction barrier for carbon monoxide formation, which makes it easier to form liquid products. Therefore, the "on-off" topological surface state significantly regulates the performance of the CO2 electrocatalytic reduction reaction.
According to the researchers, the study provides direct experimental evidence for the condensation of the structure-activity relationship between the topological surface state of bismuth selenide and the performance of carbon dioxide electrocatalytic reduction reaction by accurately "switching" the topological surface state, and opens up a new direction of topological quantum catalysis. (Reporter Wang Qiao).