Ga based Sillenite-TiO2 composite for efficient sunlight induced photo reduction of Cr (VI) and photo degradation of ampicillin

Abstract

This work reports the design and development of an efficient sillenite based visible light photoactive Bi₂₄Ga₂O₃₉-TiO₂ (BGT) heterostructure. Structural and morphological studies based on X-ray diffraction (XRD) and high-resolution scanning electron microscopy (HRSEM) confirm the formation of combined phase as well the overall morphology of composite BGT. Additionally, X-ray photoelectron spectroscopy (XPS) results confirm the presence of Bi³⁺, Ga³⁺, Ti⁴⁺ & O^2-. The composite exhibits a shift in the absorbance edge towards visible region of electromagnetic spectrum when compared to that of TiO₂. Suitable band edge positions in the composite facilitate the formation of type-1 heterojunction enhancing visible light photocatalytic property. The photocatalytic activity is evident from photo reduction of Cr (VI) (95% reduction in 180 min). The composite also plays an improved and effective role in the degradation of persistent drug ampicillin-cloxacillin (AMC) with a rate constant of 0.02 min^-1. Photocatalytic experiments conducted at different pH values showed higher performance at lower pH ∼3. Trapping experiments performed on the sample confirm the role of holes as the main active species during photocatalysis. Appreciable recyclability of BGT composite was noted with respect to AMC drug degradation.

Keywords: Ampicillin antibiotic drug; Bi(24)Ga(2)O(39); Composite; Cr (VI) reduction; Photocatalytic; TiO(2).