Boosted photocatalytic activity of LaFeO3/Ag3PO4 heterojunction via carbon quantum dots: Higher conductivity, stability, and dispersivity

Abstract

Several restrictions including low photon conversion efficiency, unabiding material stability, and aggregation behavior hinder large scale applicability of conventional semiconductor photocatalysts for pollutants removal. In this work, the inexpensive carbon quantum dots (CQDs) was synthesized by facile one-step hydrothermal process and introduced into LaFeO3/Ag3PO4 nanocomposites for photodegradation of organic dyes. The morphology, surface chemical states, optical and electrochemical properties of as-prepared samples were systematically investigated using HRTEM, FT-IR, XPS, UV–vis,UV–vis, and PL. LaFeO3/Ag3PO4 with 3 wt% of CQDs presented the higher photocatalytic activity with 97.3 % removal rate of methylene blue (MB) organic dyes under 60 min visible light irradiation, which were three times that of the binary LaFeO3/Ag3PO4 composites. The effect of initial pH and co-existing inorganic ions on MB removal efficiency, particle aggregation behavior during photocatalytic process, and dominant reaction active species were investigated. The results showed that CQDs significantly improved the photoelectrochemical (PEC) performance of LaFeO3/Ag3PO4 composites, as well as protected Ag3PO4 from photo corrosion due to variation of electronic transfer path in composite material. Benefitting from numerous oxygen and nitrogen-containing functional groups, CQDs as a dispersing agent, improved water dispersibility and wettability of photocatalyst particles, and inhibited agglomeration of nano-photocatalyst on photocatalytic reactivity. These findings highlight the potential utility of CQDs in assisting a rapidly photodegrading molecular dye in an aqueous solution.