Ternary CdS-MoS2 coated ZnO nanobrush photoelectrode for one-dimensional acceleration of charge separation upon visible light illumination

Abstract

Ternary CdS-MoS2 coated ZnO nanobrush photoelectrode from chemical bath deposition was successfully fabricated on a FTO substrate for photocatalytic degradation of amoxicillin. The vertically grown ZnO core on FTO substrates provided a direct pathway for electron transfer; while the well-crystallized CdS/MoS2 shell offered effective visible light absorption and increased active sites. Prolonged lifetime of charge carriers was demonstrated by transient photovoltage (TPV) measurement. The ternary brush-type electrode exhibited enhanced photoelectrochemical performance with a photocurrent density of 20.32 mA/cm2 at 0 V vs. Ag/AgCl under visible light illumination (λ ≧ 420 nm), which was 5.2 times, 1.8 times and 3.6 times of that of pristine CdS, CdS-MoS2 film and ZnO/CdS nanobrush, respectively. The improved photoelectrochemical activity was ascribed to the enhancement of light absorption, appropriate band alignment and prolonged charge carriers’ lifetime. The ZnO/CdS-MoS2 nanobrush film degraded 94% of amoxicillin in 60 min, exhibiting promising photocatalytic activity under visible light illumination (λ ≧ 420 nm). The reusability and stability of the electrode were evaluated by recycling experiments. The intermediates of amoxicillin oxidation were also identified and the degradation pathway was proposed.