Study on micro-nanocrystalline structure control and performance of ZnWO4 photocatalysts

ZnWO 4 micro/nanocrystals with different sizes and well-developed crystals were synthesized by the molten salt method at low temperature. The crystal structure and growth morphology of the ZnWO 4 crystals were characterized and the crystalline and band structure of ZnWO 4 was simulated using Materials Studio software to reveal the relationship between crystal structure, surface morphology and properties. The results show that the ZnWO 4 single crystal can be obtained at 500 °C for 12 h. The photocatalytic activity of the nanocrystalline ZnWO 4 crystals prepared at different calcining times is decreased in the order 12 h > 24 h > 6 h > 0 h and the fluorescence emission intensity of the ZnWO 4 crystals prepared at 500 °C for 24 h exhibited strong photoluminescence properties. The photocatalytic and photoluminescence properties of the ZnWO 4 crystals were closely related to the crystal structure, micromorphology and crystal size. Based on the theoretical calculation of the energy band structure, the photoexcited electrons transmitted from the O 2p orbitals at the top of the VB to the empty W 5d orbitals at the bottom of the CB and the larger photoelectric transmission rate can inhibit the recombination of electron-hole pairs and promote the photocatalytic reaction. In contrast, the binding and complexation of carriers contributed to the manifestation of photoluminescence performance. ZnWO 4 micro/nanocrystals with different sizes and well-developed crystals were synthesized by the molten salt method at low temperature.