Li Jianfeng, Professor of Xiamen University and his collaborators have made new breakthroughs in the study of oxygen reduction mechanism on the surface of platinum single crystal

Recently, Professor Li Jianfeng, School of chemistry and chemical engineering, Xiamen University, made a great breakthrough in the study of in situ Raman spectroscopy of the orr reaction mechanism at the platinum single crystal interface Relevant research results were published in nature energy (DOI: 10.1038 / s41560-018-0292-z) under the title of "in situ Raman specific evidence for oxygen reduction reactionintermediates at platform single crystal surfaces" The oxygen reduction reaction (ORR) on the surface of platinum based catalyst is the most important cathodic reaction in fuel cell Although after decades of research, the specific response path of orr is not really clear It is generally believed that the orr process on platinum surface can be divided into two categories: one is that oxygen molecules eventually generate water or Oh through the 4-electron reduction process; the other is that oxygen molecules generate peroxides through the 2-electron reduction process However, there is no consensus on the reaction path of orr process on the surface of Pt based catalysts, because many trace and short-lived intermediate species are involved in the process, which is difficult to be effectively captured At the same time, the complex electrochemical environment also challenges the study of orr reaction path and mechanism Although the smooth single crystal surface at the atomic level has certain surface atomic arrangement structure and surface energy level, it is an ideal model system for correlation experiment and theory However, it is difficult to obtain the enhanced Raman signal and the direct spectral evidence on the atom level smooth single crystal surface, which limits people's understanding of the orr reaction process and guides the preparation of highly active catalysts In this study, Professor Li Jianfeng's research group first used the electrochemical shell isolated nanoparticles enhanced Raman spectroscopy (shiners) technology developed by him to study the orr reaction process on the surface of Pt (hkl) single crystal, and successfully captured O 2 -, OH * and HO 2 in the 1150cm-1, 1080cm-1 and 732cm-1 domains* Based on the direct Raman spectra of some important intermediate species, the corresponding isotope substitution experiments and DFT theoretical simulation confirmed the peak assignment and adsorption configuration of the intermediate species The orr reaction mechanism on the surface of Pt (hkl) single crystal in acid condition is that O2 molecules first adsorb on Pt (hkl) single crystal electrode to form the adsorbed O2 * and then form the HO 2 * species after proton electron transfer Then the O-O bond breaks and forms a pair of adsorbed o * and OH * on the adjacent platinum atom Finally, OH * forms H 2O by proton electron transfer Because the Gibbs free energy and activation energy of the same intermediate species on different crystal surfaces are different, the existence state and the subsequent orr reaction are difficult to be different, so the orr activity on Different Pt (hkl) crystal surfaces is obviously different In general, the direct Raman spectrum evidence of the important intermediate species of orr reaction was obtained in situ on the surface of Pt (hkl) single crystal for the first time, and a reasonable orr reaction path was proposed, which deepened people's understanding of the orr reaction mechanism and provided a feasible research idea for the study of other interface catalytic reaction mechanism The research work was jointly completed by several research groups inside and outside Xiamen University Professor Li Jianfeng's research group was responsible for the related electrochemical in-situ Raman spectroscopy experiment, Professor Juan Feliu's research group of Alicante University in Spain was responsible for the single crystal electrochemical experiment, and Professor Wu Deyin's research group of School of Chemistry and chemical engineering of Xiamen University was responsible for the DFT theoretical simulation, The research group of Professor Yang Zhilin in the Department of physics is responsible for the theoretical simulation of 3D-FDTD Dong Jinchao, the first author of the research, and Zhang Xiaguang, the second author, are 2014 level doctoral students (graduated) and 2015 level doctoral students respectively from the school of chemistry and chemical engineering of Xiamen University The research work was greatly supported by NSFC (21522508, 21427813, 21521004, 21533006, 21621091 and 21775127) Professor Zhou Zhiyou and Professor Cheng Jun, School of chemistry and chemical engineering, Xiamen University, Associate Professor Zhang Hua, School of materials, Professor Gary Attard, University of Liverpool, UK, as well as Dr Su min, Wang Yaohui, Lu Bangan and Dr Yang Xiaodong gave strong support and help to the research.