Nanosized ZnWO4 photocatalysts were successfully synthesized via the sol-gel process in a temperature range of 450-800 ℃.The grain size,crystal size,and crystallinity of ZnWO4 particles increased with the increase of calcination temperature and prolonging calcination time.The photocatalytic activity was measured for the degradation of an aqueous Rhodamine-B(RhB)solution and gaseous formaldehyde(FAD).With the increase of calcination temperature and time,the activities increased to a maximum and then decreased.ZnWO4 photocatalyst prepared at 550 ℃ for 10 h showed the highest activity,which is similar to the photocatalytic activity of P25TiO2 for the degradation of gaseous FAD.High crystallinity,large surface area,and good dispersion are responsible for the high photocatalytic performance of the prepared ZnWO4.
