Decoration of ZnO surface with tiny sulfide-based nanoparticles for improve photocatalytic degradation efficiency

Modifying wide band gap ZnO nanoparticles surface by combine narrow bandgap semiconductors is a novel route to promote the ZnO to diverse applications. Herein, different metal sulfides (CdS, Ag2S and Bi2S3) were decorated on ZnO surface using facile a chemical route for photocatalytic application. Crystal structure, surface morphology and optical changes for the surface modified ZnO were studied by using various characterization techniques. The XRD spectra exhibited mixed phase of decorated metal sulfide nanoparticles along with strong pattens of hexagonal structure ZnO. The SEM images were confirmed that tiny CdS, Ag2S and Bi2S3 sulfide nanoparticles are well decorated on ZnO hexagonal rods surface. Band gap of the ZnO was tuned into visible region by modifying the surface by the sulfide nanoparticles. Textile industry-based crystal violet (CV) dye was used as a model pollutant to evaluate the photocatalytic activity of sulfides decorated well-crystalline ZnO photocatalysts under natural sunlight. Among the three catalysts, the Ag2S decorated ZnO achieved greatest photodegradation efficiency of 94.1% for degradation of the CV dye with rate constant value of 0.050. The highest catalytic activity may be related to Ag2S acting a significant part in reducing bandgap and boosting hole, superoxide radical, and hydroxyl radical formation, which inhibits recombination, hence enhancing the pho-tocatalyst's efficacy, activity, and also stability.

Automated summary

Modifying the surface of wide band gap ZnO nanoparticles with narrow bandgap semiconductors is an effective approach to enhance its applications. In this study, metal sulfides (CdS, Ag2S, and Bi2S3) were used to decorate ZnO surface for photocatalytic application. The crystal structure, surface morphology, and optical properties of the modified ZnO were characterized. The results showed the presence of decorated metal sulfide nanoparticles on ZnO surface, which tunned the band gap of ZnO into the visible region. Among the three catalysts, Ag2S decorated ZnO exhibited the highest photodegradation efficiency and catalytic activity for the degradation of crystal violet dye under natural sunlight.