Enhanced sunlight photodegradation activity of methylene blue using Mn doped SnO2 loaded on corn cob activated carbon

Abstract

In this work, Mn doped SnO2 loaded with a (0.5 ​g) corn cob activated carbon (Mn: SnO2/CCAC) are successfully synthesized by chemical precipitation method and its photocatalytic performance was estimated by photodegradation of methylene blue (MB) under sunlight irradiation. The materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (UV–Vis, DRS), photoluminescence (PL), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray analysis (EDAX), Brunauer-Emmett-Teller (BET) surface area and electrochemical impedance spectroscopy (EIS) analysis. The XRD results confirmed the rutile tetragonal crystalline structure and average crystalline size is decreased (13.79 ​nm) upon Mn doping and CCAC loading samples. The band gap value (Mn: SnO2/CCAC) is decreased (3.49 ​eV) compared to pure SnO2 and Mn doped SnO2 samples. Further, reduced PL emission intensity of Mn: SnO2/CCAC and its reduced value of impedance from EIS analysis and enhanced separation of the photogenerated electron-hole pairs, supports the enhanced photodegradation efficiency. As a result, the optimum Mn (0.10 ​M) doped SnO2/CCAC of the removal efficiency (97.76%) of MB dye reveals both improves photocatalysts (Mn-doped SnO2) and adsorption (CCAC) under sunlight within 120 ​min. The mechanism for the enhancement of photocatalytic activity under sunlight irradiation is also proposed.