Synthesis of mesoporous NiWO4 nanocrystals for enhanced photoelectrochemical water oxidation

• Synthesis of mesoporous NiWO4 nanoparticles.
• Amphiphilic organosilane surfactant was utilized to generate mesoporosity.
• Significantly improved visible-light-driven photoelectrochemical water oxidation with mesoporous NiWO4.
• Comparative photoelectrochemical water oxidation efficiency of mesoporous NiWO4 with TiO2 and nonporous NiWO4.

Nanocrystalline mesoporous nickel tungstate (m-NiWO4) was synthesized via surfactant assisted hydrothermal templating technique. TEM, HRTEM and N2 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 m2 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-NiWO4 exhibited much better photoelectrochemical H2O oxidation than TiO2 and non-mesoporous NiWO4 nanocrystals due to the enhanced crystallinity, surface morphology and mesoporosity.