Constructing visible light induced direct dual Z scheme heterostructure for photodegradation of organic pollutants

Abstract

newline xi newlineABSTRACT newlineIn the present work, a novel and highly efficient direct dual PANI/Ag2O/Cu2O (PAC) Z-scheme and Bi2WO6/Fe2O3/WO3 S-scheme heterojunction, prepared by ultrasonic assisted wet impregnation approach and used for the photodegradation of methylene blue (MB) in the presence of H2O2. The as-prepared ternary heterojunction exhibited an excellent wide-spectrum response to wavelengths ranging from ultraviolet (UV) to near-infrared (NIR), indicating its potential for effective utilization of solar energy. The nanocomposites characterized by different spectral and microscopic technologies which confirm the formation of nanocomposites such as surface morphology, particle size, hkl planes and d-spacing was analysed using scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM), the phase purity and crystalline structures were affirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) which is used to detect chemical bonds of the composites, Brunauer Emmett Teller (BET) to investigate specific surface area, X-ray photoelectron spectroscopy (XPS) to investigated the elemental composition of nanocomposites and the electron immigration in the heterojunction. The energy bandgap of nanocomposites was calculated from Ultraviolet-visible-near infrared diffuse reflectance (UV Vis-DRS-NIR) and Ultraviolet-visible diffuse reflectance (UV Vis-DRS) spectroscopy, which indicated the usability as a photocatalyst under UV-Vis-NIR and visible light. The photoluminescence analysis confirmed reduction in recombination of photogenerated electron and hole pairs. Photocurrent and electrochemical impedance spectroscopy results further demonstrated that the composites exhibited higher photocurrent density and lower charge transfer resistance than those of the pure photocatalyst. Magnetic behavior of sample detect by Vibrating sample magnetometer (VSM), high performance liquid chromatography analysis (HPLC) and liquid chromatography mass spectroscopy (LCMS) was performed to analyze the degradation products, electron spin resonance spectra (ESR) and trapping experiment to detect the active species in the photocatalytic system. The effect of catalyst dosage, initial pH, effect of pollutant concentration, H2O2 concentration and presence of inorganic anions of solution on photocatalytic efficiency was investigated. The synergistic effect between the PAC nanoparticles exhibits superior catalytic activity with 98% of MB degradation with 40 min in the presence of H2O2 under the UV-Vis-NIR spectrum. Other than this, degradation efficiency bisphenol-A (BPA) newlinexii newlinereached up to 99% with 30min in the presence of BFW photocatalyst under visible light. This work provides new insights for the design of a novel direct dual based heterojunction for highly efficient simultaneous photocatalytic degradation. newlineKeywords: Photocatalysis, Direct dual Z-scheme heterojunction, Direct dual S-scheme heterojunction, Visible light driven photocatalyst, NIR active photocatalyst, Methylene blue, Bisphenol -A.