Plasmon enhanced photocatalytic degradation of 4-chlorophenol using zinc oxide nanorods decorated with gold nanoparticles as supported catalysts under natural sunlight

Abstract

The photocatalytic degradation of 4-chlorophenol (4-CP) was evaluated under natural sunlight using zinc oxide nanorods (ZnO NRs) and gold nanoparticles (AuNPs) decorated ZnO NRs catalysts. Microwave-assisted hydrothermal growth of ZnO NRs followed by photoinduced deposition of AuNPs on ZnO NRs was carried out to fabricate the ZnO-Au catalysts. The photocatalytic degradation of 4-CP with different AuNPs sizes and surface coverage obtained from varying Au loading on ZnO NRs was studied. 0.1 mM AuNPs concentration exhibited the best result, with a degradation efficiency of 97% for 10 ppm of 4-CP within 180 min. The degradation enhancement for the ZnO-Au catalysts was owing to enhanced absorption in the visible region. The visible-light-induced localized surface plasmon resonance property of AuNPs reduced the recombination and promoted the electrons and holes separation. The substantial change in the binding energy of the valance band maximum exhibited the charge transfer from AuNPs to ZnO NRs. Photocatalytic degradation of four different concentrations (10, 50, 100, and 200 ppm) of 4-CP was studied. During the photocatalytic degradation, various hydroxylated intermediates formed, namely hydroquinone, benzoquinone, 4-chlorocatechol, and 4-chlororesorcinol. The photocatalytic results indicate that the ZnO-Au catalyst is a promising candidate for environmental decontamination of organic pollutants in the aqueous media.