Ultrasonically synthesized core-shell Au/Pt nanoparticles decorated g-C3N4heterostructures for enhanced sunlight-driven photocatalytic degradation of aflatoxin B1 in domestic wastewater

Abstract

The discharge of domestic wastewater from washing agricultural products contaminated with aflatoxin B1 (AFB1), even at low concentrations, poses significant risks to food chain integrity and public health. Core-shell Au/Pt nanoparticles anchored on a g-C3N4 heterostructure (Au-PtNPs/g-C3N4) were developed as a highly promising photocatalyst for the efficient degradation of AFB1 in domestic wastewater treatment applications. Herein, core-shell Au-PtNPs were synthesized via a straightforward one-step chemical reduction method assisted by ultrasonic irradiation. The core-shell Au-PtNPs (46.52±0.15nm) were uniformly anchored onto the g-C3N4 nanosheets via hydrogen bonding during ultrasonic dispersion. The Au-PtNPs/g-C3N4 composites were systematically characterized and evaluated for AFB1 photodegradation. Complete removal of AFB1 (50μgL-1) was accomplished within just 1min under natural sunlight using 0.50mg of catalyst at pH 7.0, demonstrating a 6.7-fold enhancement over pristine g-C3N4. Mechanistic investigations confirmed that the AuNPs core induced a surface plasmon resonance (SPR) effect that broadened visible-light absorption, while the PtNPs shell served as an efficient electron sink, facilitating charge separation. Simultaneously, the g-C3N4 nanosheets functioned as a visible-light-responsive photoactive scaffold, promoting effective charge generation and directional migration across the heterojunction interface. These synergistic effects were validated by diffuse reflectance UV-vis spectroscopy, linear sweep voltammetry, electrochemical impedance spectroscopy, photoluminescence quenching, and Mott-Schottky analysis. The combined enhancements significantly promoted the generation of reactive oxygen species (•O-2, •OH and h∗), driving the efficient photodegradation of AFB1. Thus, the Au-PtNPs/g-C3N4 photocatalyst provides a promising, sunlight-driven strategy for AFB1 detoxification in real wastewater from domestic, agricultural and food industry sources.