Synthesis of ZnWO4 Electrode with tailored facets: Deactivating the Microorganisms through Photoelectrocatalytic methods

Abstract

The exotic invasive species from the ballast water in the ship will bring about serious damages to ecosystem. Photocatalyst films have been widely studied for sterilization. In this study, ZnWO 4 with different exposed facets was synthesized by hydrothermal method, and ZnWO 4 film electrodes have been applied in ballast water treatment through the electro-assisted photocatalytic system. Then the samples were investigated by X-ray diffraction (XRD), X-ray photo-electron spectroscopy (XPS), Field emission on scanning electron microcopy (FE-SEM), Transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), BET specific surface area analysis, Fourier transform infrared (FT-IR) and Electrochemical impedance spectra (EIS). ZnWO 4 with an appropriate exposure of (0 1 1) facets ratio exhibited the best photocatalytic and photoelectrocatalytic activities. The microorganisms deactivated completely in 10 min by ZnWO 4 films with 3 V bias. The mechanisms of (0 1 1) facets enhanced the photocatalytic and photoelectrocatalytic activities which were deduced based on the calculated result from the first principles. Simultaneously, appropriate exposed facets and applied bias could reduce the recombination of the photogenerated electron-hole pairs, and improve the photocatalytic activities of ZnWO 4 .

Strong Photo-Oxidative Capability of ZnWO4 Nanoplates with Highly Exposed {0 1 1} Facets

“…The diffraction spots of most important crystallographic planes are labeled in Figure 2. From the Miller index of the diffraction spots, the zone axis of ZnWO 4 nanoplates was determined to be [011]. In this way, the normal line of the nanoplate was determined as [011].…”

“…Zinc tungstate (ZnWO 4 ) is known for its use as an efficient scintillator [1], phosphor [2], photocatalyst [3], and photoelectrocatalyst [4,5]. In order to solve the serious environmental problem of organic contaminants in waste water by harnessing the solar power of sunlight, a variety of ZnWO 4 nanostructures were intensively investigated as photocatalysts [6][7][8][9][10][11][12].…”

“…In spite of the progress achieved in the past 20 years, no data were given to demonstrate if these ZnWO 4 nanostructures can completely mineralize the fragments of organic pollutants into waste water . Since the intermediates formed through the photocatalytic reactions are often more toxic than the original organic contaminants in waste water, it is critically important for the ZnWO 4 photocatalysts to have such a strong photo-oxidative capability that they can completely mineralize these harmful intermediates.…”

“…that ZnWO 4 nanoplates will have quite different photocatalytic performance with respect to ZnWO 4 nanoparticles. However, the profound influence of the crystal facet on the photocatalytic activity of ZnWO 4 attracted little attention [4]. In our previous report, Eu 2+ and Eu 3+ doubly doped ZnWO 4 nanoplates were synthesized, and their light-emitting properties and electronic structures were studied [28].…”

Eu2+ and Eu3+ Doubly Doped ZnWO4 Nanoplates with Superior Photocatalytic Performance for Dye Degradation

“…Belonging to a wide group of wolframite-type tungstates, zinc tungstate (ZnWO 4 ) is a technologically important material for numerous applications in the fields of luminescent materials [1,2,3,4,5], photocatalysts [6,7,8,9,10,11,12,13,14], Li-ion batteries [15], humidity sensors [16], materials for stimulated Raman scattering [17], and materials for deactivating microorganisms [18]. Among these applications, the photocatalytic properties of ZnWO 4 nanostructures have been intensively investigated in order to solve one of the most serious environmental problems in our modern society via semiconductor-based photocatalytic degradation of organic contaminants in water under sunlight [6,7,8,9,10,11].…”