Synthesis and characterization of nanostructured molybdenum oxynitride films fabricated by sub-atmospheric chemical vapor deposition

摘要

To support the trend of a new green energy introduction in economics it has become urgent nowadays that more available and cheaper materials would substitute noble and/or expensive materials (Au, Ag, Pt, Pd, Ga.). Therefore, we studied molybdenum oxynitride films due to their catalytic properties. Molybdenum oxynitride films were fabricated by sub-atmospheric chemical vapor deposition (SACVD). According to Raman spectroscopy, grown platelets possessed MoO3 structure up to 12 at. % NH3 in NH3/air mixture. With the increasing amount of NH3 in the reaction atmosphere (16-25 at. % NH3), the films became heterogeneous containing Mo4O11 and MoO2 suboxides. Nanostructures - nanorods, nanoribbons - developed gradually at those samples with highest concentrations of NH3 in the atmosphere (25-33 at. % NH3) whose structure was built by blocks of corner-sharing Mo-octaedra separated by double layers of edge-sharing Mo-octaedra, which was revealed by Electron Diffraction Tomography (EDT). X-ray Photoelectron Spectroscopy (XPS), similarly to Raman spectroscopy, showed a gradual rise of molybdenum suboxides with NH3 increase in the atmosphere, which was indicated by the successive appearance of Mo6+ -> Mo5+ -> Mo4+ species. As N 1s XPS signal was fully overlapped by the Mo 3d(5/2) one, a new procedure of a standard selected was used for the estimation of the nitrogen content in the films. This material was capable of reducing water under illumination as found by Cycling Votammetry (CV). (C) 2019 Elsevier B.V. All rights reserved.