Investigation of Re and Nb doped molybdenium disulfide by x-ray spectroscopy methods
Transition metals disulfides are currently being actively studied due to their interesting physicochemical properties. Modification of these compounds by doping atoms makes it possible to obtain materials with the necessary electronic properties. In particular, molybdenum disulphide is promising for use in such areas as catalysis , transistors fabrication , production of lithium-ion batteries . In this work we investigated solid solutions with stoichiometry Mo1-xMxS2, x = 0, 0.05, 0.1, 0.15, 0.2 based on MoS2, doped with electronically redundant Re atoms and electron-deficient Nb atoms. The structure of the conduction and valence band will depend strongly on concentration and type of doping atoms. The dependence of the band gap on the dopant concentration was experimentally determined from the valence band XPS and the XANES edges. XANES and valence band XPS were obtained on the Russian-German RGBL beamline at BESSY II synchrotron source. The use of the TEY and PEY modes for XAFS experiments made it possible to obtain surface spectra and the spectra of bulk and surface superposition. The effect of surface defects on electronic structure was evaluated. To complete the study the XPS and the XES were obtained. According to the results of XES and XPS studies, we assume that Re-clusters are formed even at low dopant concentrations in the samples. This assumption was confirmed by the HRTEM method .
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