Highly photoactive SnO2 nanostructures engineered by electrochemically active biofilm

This paper reports the defect-induced band gap narrowing of pure SnO2 nanostructures (p-SnO2) using an electrochemically active biofilm (EAB). The proposed approach is biogenic, simple and green. The systematic characterization of the modified SnO2 nanostructures (m-SnO2) revealed EAB-mediated defects in the pure SnO2 nanostructures (p-SnO2). The modified SnO2 (m-SnO2) nanostructures in visible light showed the enhanced photocatalytic degradation of p-nitrophenol and methylene blue compared to the p-SnO2 nanostructures. The photoelectrochemical studies, such as the electro-chemical impedance spectroscopy and linear scan voltammetry, also revealed a significant increase in the visible light response of the m-SnO2 compared to the p-SnO2 nanostructures. The enhanced activities of the m-SnO2 in visible light was attributed to the high separation efficiency of the photoinduced electron hole pairs due to surface defects mediated by an EAB, resulting in a band gap narrowing of the m-SnO2 nanostructures. The tuned band gap of the m-SnO2 nanostructures enables the harvesting of visible light to exploit the properties of the metal oxide towards photodegradation, which can in turn be used for environmental remediation applications.