Free-polymer controlling morphology of alpha-MoO3 nanobelts by a facile hydrothermal synthesis, their electrochemistry for hydrogen evolution reactions and optical properties

Abstract

Orthorhombic molybdenum oxide (alpha-MoO3) nanobelts were successfully synthesized by the 100-180 degrees C and 2-20 h hydrothermal reactions of (NH4) 6Mo7O24 center dot 4H(2)O solutions containing 15 ml 2 M acid (HNO3, H2SO4 or HCl) with no surfactant and template adding. These products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy, and electron microscopy (EM). In the present research, the product synthesized by the 180 degrees C and 20 h hydrothermal reaction of the solution containing HNO3 was alpha-MoO3 nanobelts with >10 mu m long and <200 nm wide. Electrochemistry for hydrogen evolution reactions (HER) and optical properties of the as-synthesized alpha-MoO3 nanobelts were characterized by linear sweep voltammetry (LSV) and Tafel plot, including UV-vis and photoluminescence (PL) spectroscopy. These imply that alpha-MoO3 nanobelts show satisfied performance for HER, with the 3.75 eV direct allowed band gap (E-g) due to the charged transition of O-2p -> Mo-4d, including the emission of 437 nm wavelength at room temperature. (C) 2011 Elsevier B. V. All rights reserved.