Morphological control of Ni loaded electrospun W:BiVO4 nanofibers and their photocatalytic activity for water splitting

Abstract

The rising human demand for developing clean and renewable energy has been promotive of photochemical/photoelectrochemical water splitting as a pathway to convert solar energy into chemical energy. Nanostructured catalysts are widely regarded as an opportunity to improve light harvesting and conversion efficiency for water splitting. For the water oxidation catalyst, 1D nanostructured tungsten doped bismuth vanadate nanofibers (W:BiVO4 NFs) with high specific surface area (SBET = 13.656 m2/g) were successfully prepared by facile electrospinning method. Nickel nanoparticles (Ni NPs) with diameter of 5-10 nm as co-catalysts for lowering the activation barrier of water redox reactions and assisting in charge separation near the co-catalyst and semiconductor interface were synthesized by the polyol method. Ni NPs decorated W:BiVO4 nanofibers (Ni/W:BiVO4 NFs) were characterized using X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM) and Transmission electron microscopy (TEM). The results proved that the elongated W:BiVO4 NFs in longitudinal direction had many small grains with monoclinic scheelite structure and bimodal pore distribution. The surface of W:BiVO4 NFs was covered in patches with the Ni NPs mostly comprised of the Ni metal phase. Photocatalytic activity of the prepared samples was measured by oxygen evolution test with sacrificial electron scavenger (AgNO3) and photo-absorption property of them was measured by diffuse-reflectance spectra. In the final analysis, the photocatalytic activity in water oxidation reactions was significantly improved by introducing Ni NPs on W:BiVO4 NFs in comparison with that of W:BiVO4 bulk or pristine W:BiVO4 NFs. In the results of the absorption properties and band gap calculation, Ni/W:BiVO4 NFs make a loss to harvesting photon energies. However, this negative effect is explicitlyexplicitly explicitlyexplicitlyexplicitlyexplicitlyexplicitlyexplicitly overcompensat...