3D atomic mapping of rutile-TiO2(110) supported Vanadium oxide catalyst using X-ray Standing Wave excited XPS

XSW excited XPS was used to study atomic-scale structure of 1/2 monolayer vanadium oxide catalyst supported on rutile TiO2(110) single crystal. The experiments were performed at I09 beamline at the Diamond Light Source. Collecting V 2p, O 1s and Ti 2p XPS signals as we scanned across a Bragg peak at different stages of a redox reaction allowed tracking of surface sites for chemically distinct V atoms, important for understanding their catalytic behaviour. V5+ and V4+ 2p XPS peaks were found to be separated by 1.4 eV and were found to have different XSW coherent fraction and position. Summation of these Fourier components for 5 symmetry inequivalent hkl Bragg peaks generates a chemical state sensitive 3D atomic map of vanadium. These results give us unique insights into this as well as other related oxide supported catalysts.