Effect of mixed Mo/W polyoxometalate modification on photoelectrocatalytic activity of CdS nanocrystals for arsenic(III) oxidation

Modification of semiconductor materials by polyoxometalates (POMs) is a promising strategy for increasing their photoelectrocatalytic (PEC) activity. In this work, we synthesized POM-modified CdS composite nanocrystals based on three kinds of Keggin-type mixed-addendum Mo/W POMs (Ag 3 PMo 3 W 9 O 40 , Ag 3 PMo 6 W 6 O 40 , and Ag 3 PMo 9 W 3 O 40 ). This is the first report on the semiconductor properties of the three Keggin-type mixed-addendum Mo/W POMs. Their PEC performances were studied by transient photocurrent responses, electrochemical impedance spectroscopy , and PEC oxidation of As(III) to As(V). The PEC performances of POM-modified CdS composite nanocrystals (CdS/Ag 3 PMo 3 W 9 O 40 , CdS/Ag 3 PMo 6 W 6 O 40 , and CdS/Ag 3 PMo 9 W 3 O 40 ) were superior to the performance of pure CdS nanocrystals. CdS/Ag 3 PMo 3 W 9 O 40 composite nanocrystals exhibited the highest efficiency for the PEC oxidation of As(III) to As(V), which was about 85% higher than that of the pure CdS nanocrystals. The present study provides insight into developing novel composite nanocrystals with Keggin-type mixed Mo/W POMs for efficient PEC oxidation.