Photocatalysis and photoelectrochemical properties of tungsten trioxide nanostructured films.
Tungsten trioxide (WO₃) possesses a small band gap energy of 2.4-2.8 eV and is responsive to both ultraviolet and visible light irradiation including strong absorption of the solar spectrum and stable physicochemical properties. Thus, controlled growth of one-dimensional (1D) WO₃ nanotubular structures with desired length, diameter, and wall thickness has gained significant interest. In the present study, 1D WO₃ nanotubes were successfully synthesized via electrochemical anodization of tungsten (W) foil in an electrolyte composed of 1 M of sodium sulphate (Na₂SO₄) and ammonium fluoride (NH₄F). The influence of NH₄F content on the formation mechanism of anodic WO₃ nanotubular structure was investigated in detail. An optimization of fluoride ions played a critical role in controlling the chemical dissolution reaction in the interface of W/WO₃. Based on the results obtained, a minimum of 0.7 wt% of NH₄F content was required for completing transformation from W foil to WO₃ nanotubular structure with an average diameter of 85 nm and length of 250 nm within 15 min of anodization time. In this case, high aspect ratio of WO₃ nanotubular structure is preferred because larger active surface area will be provided for better photocatalytic and photoelectrochemical (PEC) reactions.
Nanotechnology & Catalysis Research Centre (NANOCAT), Institute of Postgraduate Studies (IPS), University of Malaya, 3rd Floor, Block A, 50603 Kuala Lumpur, Malaysia.
Chin Wei
CW
Lai
D064751:Ammonium Compounds; D002384:Catalysis; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004573:Electrolytes / Q000737:chemistry; D005459:Fluorides / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D008027:Light; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning / Q000379:methods; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects* / Q000648:ultrastructure; D010084:Oxidation-Reduction / Q000528:radiation effects; D010087:Oxides / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D013499:Surface Properties; D014414:Tungsten / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D064751:Ammonium Compounds; D004573:Electrolytes; D008567:Membranes, Artificial; D010087:Oxides; D000644:Quaternary Ammonium Compounds; D013431:Sulfates; D014867:Water; C012036:sodium sulfate; C024822:ammonium fluoride; D006859:Hydrogen; C511604:tungsten oxide; D005459:Fluorides; D014414:Tungsten