Synthesis of ZnWO4−x nanorods with oxygen vacancy for efficient photocatalytic degradation of tetracycline

Abstract

Persistent organic pollutants (POPs) especially tetracycline pose a great threat to human health, and the photocatalytic degradation of tetracycline by ZnWO4 nanomaterials has drawn much attention. To improve the photo-response range and photoactivity, we prepared ZnWO4−x sample with oxygen vacancies by solvothermally treating Zn(NO3)3 and Na2WO4 in water/ethanol/PEG-400 mixture where ethanol could act as a reducing agent to selectively remove some oxygen atoms from ZnWO4. ZnWO4−x sample is composed of nanorods with length of ~50 nm and diameter of ~20 nm. Furthermore, ZnWO4−x nanorods are brown and exhibit the obviously broadened photoabsorption from ultraviolet (UV) to near infrared (NIR) region, compared with the tradition white ZnWO4 nanorod without oxygen vacancies and with UV absorption edge of 365 nm. Under the irradiation of UV or ultraviolet-visible-near infrared (UV–Vis–NIR) light, ZnWO4−x nanorods can photocatalytically degrade 91% or 78% tetracycline, higher than those (67% or 71%) by ZnWO4 nanorods. The enhanced photocatalytic efficiency can be attributed to the introduction of oxygen vacancies which have been found to reduce photogenerated electron-hole pair recombination and narrow band gap.