Presenter：Bin Liu, School of Chemical and Biomedical Engineering, Nanyang Technological University
Topic：Identification of Co2+ in Spinel Co3O4 as Active Sites for Water Oxidation
Time：09：30AM, July 21st
Location：909-B
Abstract
Spinel cobalt oxide (Co3O4) has been extensively studied as promising electrocatalyst for water oxidation. It is believed that the cobalt ions in spinel Co3O4 should be oxidized during the oxygen evolution reaction (OER). Therefore, the observed evident anodic peak prior to the rise of the OER current in the linear sweep voltammetry (LSV) scan in spinel Co3O4 was ascribed to the oxidation of cobalt ions accompanying with a phase transformation. Here, through a combination of independent in-situ measurements including X-ray absorption and grazing-angle X-ray diffraction under operando conditions, we found that both the spinel structure and cobalt valence states in Co3O4 remained unchanged during electrochemical water oxidation. Following a potential-resolved in-situ Raman analysis, it was revealed that the anodic peak current could be mainly contributed from the formation of peroxide moieties (e.g., Co-OO-Co or Co-OOH) on the surface of Co3O4, and more importantly, the tetrahedral Co2+ ions in Co3O4 should be the crucial sites to bridge the µ-OO bond.
Biography
Bin Liu received his B.Eng. (1st Class Honors) and M.Eng. degrees in Chemical Engineering from the National University of Singapore, and obtained his Ph.D. degree in Chemical Engineering from
Contact: Yanguang Li
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