Direct dual-Z-scheme PANI/Ag2O/Cu2O heterojunction with broad absorption range for photocatalytic degradation of methylene blue

Abstract

The PANI/Ag2O/Cu2O (PAC) direct dual-Z-scheme heterojunction was synthesized by ultrasonic-assisted wet impregnation method. The heterojunction utilizes broad spectrum form UV, visible to NIR region. The structural characterization and chemical composition was explored by series of instrumental techniques. A significant photodegradation rate of 275 × 10−4 min−1 against methylene blue (MB) were observed on addition of H2O2 at pH 8. H2O2 addition intensify the •OH radicals generation that photodegraded nearly 98% of MB in 40 min. Further, trapping experiment and ESR technique validate the active role of •OH, •O2− radicals and holes during photocatalytic process. Several critical factors governing the rate of photodegradation such as pH, concentration H2O2, MB and photocatalyst were also analysed. The degradation mechanism and the intermediate formed were established by performing HPLC and LCMS analysis. Lastly, the direction of charge migration, slower rate of recombination, and effective separation of charge carrier were explicit by XPS analysis and electrochemical study. Based on the obtained results, work function of independent photocatalysts and the alignment of energy bands, a plausible direct dual-Z-scheme charge migration were proposed.