Liu Zhipan and Li Yefei of Fudan University determined the active sites of layered MnOx catalytic cracking water by a new potential energy surface search method

Recently, ichem researchers, Professor Liu Zhipan, Department of chemistry, Fudan University, and Li Yefei, a young researcher, have made new progress in the study of dynamic structural transformation and catalytic activity under the condition of oxidized water Through the self-developed surface random walk algorithm (SSW), the structural transformation of Mn 3O 4 in situ under electrochemical conditions was studied, and the possible defect structure and its influence on the catalytic activity of oxidized water were clarified This work is another important breakthrough in the field of MnOx material structure after the research on the phase transition from layered to cross-linked structure of MnO2 (j.am.chem.soc., 2016, 138, 5371) The research results were published in the Journal of American Chemical Society (J am Chem SOC., 10.1021 / JACS 7b11393) under the title of "active site revealed for water oxidation on electrically induced δ - MnO2: role of spinel to layer phase transition" The source of crystal structure of Mn3O4 and δ - MnO2: J am Chem SOC Since the discovery of PSII photocatalytic water oxidation system in nature, it has a long history to search for active MnOx materials as artificial water decomposition catalyst A large number of literature reports show that the common MnOx crystal forms (such as α -, β -, δ - MnO2) have very low water oxidation activity under acidic or neutral pH conditions However, recent studies have shown that the layered δ - MnO2 structure formed in situ on spinel Mn 3O 4 under electrochemical conditions has much higher water oxidation activity than other MnOx materials, but there is no clear theoretical explanation for its internal cause In this study, the SSW route sampling method was used to elucidate for the first time the atomic level mechanism of the solid-solid phase transition from spinel Mn3O4 to layered δ - MnO2 in the solution containing water and electricity The researchers found that h 0.5 MnO 2 phase is the precursor of phase transformation at high voltage (> 1V), which then undergoes solid-solid transition and produces layered δ - MnO 2 phase In the process of phase transformation, Mn ions will be dissolved and dislocated, and water molecules and cation layers will be embedded, which will lead to the formation of defect structure Using the first principle calculation, the researchers found a special defect structure, that is, the layered edge of δ - MnO2 phase with Mn ion vacancy, which can significantly enhance the activity of water oxidation at the edge The theoretical overpotential of the defect site is only 0.59v, which is nearly 0.2V lower than the edge of the defect free δ - MnO2 Such an activity enhancement effect is due to the formation of an angular deficient mn4o4 cubic alkane structure This kind of defective cubic structure is similar to the camn4o4 cluster in PSII system in geometry and electron This work not only deepens the understanding of the structure-activity relationship between the structure and oxidation water property of Mn3O4 materials, but also provides a new idea for the design of new catalytic materials for oxidation water The research work was supported by NSFC (21533001, 91545107, 21773032, 91745201), Shanghai Science and Technology Commission (08dz2270500), Shanghai Education Commission (Oriental Scholars), etc Paper link: http://pubs.acs.org/doi/10.1021/jacs.7b11393 brief introduction of corresponding author: Professor Liu Zhipan of Fudan University: http:// Professor Liu Zhipan young researcher: http:// researcher Li Yefei