Unique and facile solvothermal synthesis of mesoporous WO(3) using a solid precursor and a surfactant template as a photoanode for visible-light-driven water oxidation

Mesoporous tungsten trioxide (WO(3)) was prepared from tungstic acid (H(2)WO(4)) as a tungsten precursor with dodecylamine (DDA) as a template to guide porosity of the nanostructure by a solvothermal technique. The WO(3) sample (denoted as WO(3)-DDA) prepared with DDA was moulded on an electrode to yield efficient performance for visible-light-driven photoelectrochemical (PEC) water oxidation. Powder X-ray diffraction (XRD) data of the WO(3)-DDA sample calcined at 400°C indicate a crystalline framework of the mesoporous structure with disordered arrangement of pores. N(2) physisorption studies show a Brunauer-Emmett-Teller (BET) surface area up to 57 m(2) g(-1) together with type IV isotherms and uniform distribution of a nanoscale pore size in the mesopore region. Scanning electron microscopy (SEM) images exhibit well-connected tiny spherical WO(3) particles with a diameter of ca. 5 to 20 nm composing the mesoporous network. The WO(3)-DDA electrode generated photoanodic current density of 1.1 mA cm(-2) at 1.0 V versus Ag/AgCl under visible light irradiation, which is about three times higher than that of the untemplated WO(3). O(2) (1.49 μmol; Faraday efficiency, 65.2%) was evolved during the 1-h photoelectrolysis for the WO(3)-DDA electrode under the conditions employed. The mesoporous electrode turned out to work more efficiently for visible-light-driven water oxidation relative to the untemplated WO(3) electrode.