Facile fabrication and enhanced visible-light photocatalytic activity of In2O3/Ag2CrO4 composites

Abstract

A series of visible-light-driven In₂O₃/Ag₂CrO₄ composites were fabricated by a facile chemical precipitation method and characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL) spectroscopy. The In₂O₃/Ag₂CrO₄ composites showed much higher photocatalytic activity and stability than those of individual Ag₂CrO₄ and In₂O₃ for the photodegradation of methyl orange (MO) under visible light irradiation (λ > 420 nm). Excitingly, the optimum degradation rate constant of the In₂O₃/Ag₂CrO₄ composite at a weight content of 4.0% In₂O₃ for the degradation of MO was 8.8 and 3.3 times as high as that of individual In₂O₃ and Ag₂CrO₄, respectively. The enhancement in photocatalytic activity and stability was predominantly attributed to the effective separation and transfer of photogenerated charge carriers as a result of the formation of a Z-scheme system composed of In₂O₃, Ag and Ag₂CrO₄. Furthermore, radical trap experiments depicted that both the holes and superoxide radical anions are main oxidative species of the In₂O₃/Ag₂CrO₄ composite for MO degradation under visible light irradiation. Finally, based on the experimental results, a possible photocatalytic mechanism has been proposed.