Investigations on the Phase Transition between CdV2O6 and Cd2V2O7 and Their Photocatalytic Performances

Abstract CdV 2 O 6 and Cd 2 V 2 O 7 were successfully synthesized by a simple hydrothermal process. The effects of the hydrothermal temperature and pH on the phase transition between CdV 2 O 6 and Cd 2 V 2 O 7 were investigated in detail. That the Cd 2 V 2 O 7 phase could transform into CdV 2 O 6 was attributed to polymerization of vanadate in an acidic environment as the V/O ratio increased as the pH decreased. V 2 O 7 4– was stable in a neutral or alkaline environment at an identical hydrothermal temperature, therefore, the Cd 2 V 2 O 7 phase was obtained after hydrothermal treatment for 24 h. Because the degree of hydrolysis of NH 4 Cl increased with increasing temperature in the solution, the increased temperature accelerated the speed of the pH decrease. Therefore, the hydrothermal temperature played an important part in the phase transition between CdV 2 O 6 and Cd 2 V 2 O 7 . CdV 2 O 6 and Cd 2 V 2 O 7 showed high photocatalytic activity for the degradation of methylene blue under visible‐light irradiation.