Novel ternary p-ZnIn2S4/rGO/n-g-C3N4 Z-scheme nanocatalyst with enhanced antibiotic degradation in a dark self-biased fuel cell

Abstract A novel ternary heterojunction nanocatalyst, p-ZnIn2S4/rGO/n-g-C3N4, was synthesized as a low-cost, high-efficiency photoelectrocatalyst. A hybrid composite of p-type ZnIn2S4, n-type g-C3N4, and GO was formed at 80 °C by a simple hydrothermal method. When installed in a dark self-biased fuel cell with cathodic Pt nanocatalysts, the anodic p-ZnIn2S4/rGO/n-g-C3N4 (83%) achieved higher triclosan (TCS) pollutant removal rate than anodic ZnIn2S4/g-C3N4 (52.3%), ZnIn2S4 (35%), and g-C3N4 (18%) after 30 min. Moreover, the p-ZnIn2S4/rGO/n-g-C3N4 not only extended the photo-response range but also accelerated the electron transfer and electron–hole separation in the absence of light or any external energy input. By comparing the different conditions in the fuel cell system, the dark condition was still comparable to the visible light and ultraviolet irradiation during the final monitoring time. scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM) were applied to characterize the morphology, composition, and structure of ZnIn2S4/g-C3N4, ZnIn2S4, and g-C3N4. Furthermore, reactive oxygen species were formed via aeration and activation of molecular oxygen through interfacial electron transfer, and active species were detected via electron spin resonance spectrometer (ESR). Finally, TCS degradation mechanisms in the self-biased fuel cell were proposed.