Synthesis of mesoporous NiWO4 nanocrystals for enhanced photoelectrochemical water oxidation

Abstract Nanocrystalline mesoporous nickel tungstate ( m -NiWO 4 ) was synthesized via surfactant assisted hydrothermal templating technique. TEM, HRTEM and N 2 sorption analysis verified the presence of mesoporous textured surface. These nanocrystals were near-spherical in shape with the size variation between 4 and 8 nm, and possessed high surface area (79 m 2  g −1 ). The nanocrystals were in monoclinic (wolframite structure) symmetry and possessed a band gap of 2.6 eV as shown by the XRD and optical measurements. The m -NiWO 4 exhibited much better photoelectrochemical H 2 O oxidation than TiO 2 and non-mesoporous NiWO 4 nanocrystals due to the enhanced crystallinity, surface morphology and mesoporosity.