Charge properties and currents in the silicon/nanoparticles of zinc oxide heterostructure irradiated by the solar light

Silicon/zinc oxide heterostructures have shown themselves to be promising for use in photovoltaics. This paper presents the results of modeling the charge properties and currents in a Si/nanosized ZnO particle with different types of conductivity under sunlight irradiation. The simulation was carried out using the Comsol Multiphysics software package. The energy diagrams of the investigated heterostructures were plotted, the charge properties and currents flowing in the structure were investigated, the dependences of the rate of generation of charge carriers on wavelength on the surfaces of silicon, zinc oxide, and at the interface between silicon and zinc oxide, the rate of recombination of charge carriers at various wavelengths of incident radiation was obtained. The regularities of the influence of wavelength of the incident radiation on the charge density and electric potential on the surface of heterostructures have been established. It is shown that the potential on the surface of the p-Si / n-ZnO heterostructure is positive, depends on the wavelength of the incident radiation and reaches the maximum of 0.68 V. For other structures, it is negative and does not depend on the wavelength: n-Si / p-ZnO –0.78 V, p-Si / p-ZnO –0.65 V, n-Si / n-ZnO –0.25 V.

Visible light responsive metalloporphyrin- sensitized TiO2 nanotube arrays for artificial photosynthesis of methane production

The conversion of CO2 and water into valuable chemicals under sunlight irradiation is of great significance for solving the widespread problems of both lacking energy sources and global warming. In...

Tosyl iodide – a new initiator for the photo-controlled iodine transfer polymerization of methacrylates under sunlight irradiation

A very simple photo-controlled iodine transfer polymerization system consisting only of methacrylate monomers, solvent (dimethylacetamide), and initiator (tosyl iodide) under violet and sunlight irradiation is reported. In this report, the...

Assembling Ultrafine SnO2 Nanoparticles on MIL-101(Cr) Octahedrons for Efficient Fuel Photocatalytic Denitrification

Effectively reducing the concentration of nitrogen-containing compounds (NCCs) remains a significant but challenging task in environmental restoration. In this work, a novel step-scheme (S-scheme) SnO2@MCr heterojunction was successfully fabricated via a facile hydrothermal method. At this heterojunction, MIL-101(Cr) octahedrons are decorated with highly dispersed SnO2 quantum dots (QDs, approximate size 3 nm). The QDs are evenly wrapped around the MIL-101(Cr), forming an intriguing zero-dimensional/three-dimensional (0D/3D) S-scheme heterostructure. Under simulated sunlight irradiation (280 nm < λ < 980 nm), SnO2@MCr demonstrated superior photoactivity toward the denitrification of pyridine, a typical NCC. The adsorption capacity and adsorption site of SnO2@MCr were also investigated. Tests using 20%SnO2@MCr exhibited much higher activity than that of pure SnO2 and MIL-101(Cr); the reduction ratio of Cr(VI) is rapidly increased to 95% after sunlight irradiation for 4 h. The improvement in the photocatalytic activity is attributed to (i) the high dispersion of SnO2 QDs, (ii) the binding of the rich adsorption sites with pyridine molecules, and (iii) the formation of the S-scheme heterojunction between SnO2 and MIL-101(Cr). Finally, the photocatalytic mechanism of pyridine was elucidated, and the possible intermediate products and degradation pathways were discussed.

Amalgamation of g-C3N4 with KNbO3 for enhanced removal of Bisphenol A under sunlight irradiation

Bisphenol A (BPA) is a pollutant exits in an enormous amount in wastewater effluent resulted from the rapid industrialization. Advanced oxidation technology (AOP) based on solar photocatalysis can be employed to solve this issue. This study will focus on adopting photocatalyst graphitic carbon nitride (g-C3N4) with potassium niobate (KNbO3) via a simple sol-gel synthesis method. The different weight percentages 0.5, 1.0 and 1.5 wt% g-C3N4, were adopted to formed KNbO3/g-C3N4composites. The physicochemical properties of the created KNbO3/g-C3N4composites were characterized with advanced analysis methods to unveil this composite’s ability to enhance the photodegradation of BPA under sunlight irradiation. It was found that 1.0 wt% KNbO3/g-C3N4composites exhibited the highest photocatalytic degradation of 69.39% in 5 h. This superior photodegradation of BPA was achieved resulted from the presence of g-C3N4that enhances light-harvesting, especially in the visible light spectrum. The increase of light-harvesting enables the composite to excite more electrons and holes leading to the massive formation of active radicals. These massive active radicals will then enhance the redox reaction and further improve the efficacy of the photodegradation of BPA. Hence, the outcome of this study path an alternative solution for eliminating complex organic pollutants in wastewater treatment.

Feasibility study of municipal wastewater removal synchronized with electricity generation via solar-driven photocatalytic fuel cell with Bi2WO6/ZnO nanorods array photoanode

The reclamation of energy from municipal wastewater treatment process is highly demanded and could resolve the two most formidable dilemmas of water pollution and energy crisis nowadays. In this study, a photocatalytic fuel cell (PFC) utilizing a Z-scheme heterojunction Bi2WO6/ZnO nanorod arrays (NRAs) photoanode was employed for efficient municipal wastewater treatment and electricity generation simultaneously under sunlight irradiation. Various characterization techniques, including energy dispersive X-ray (EDX), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), transient photoresponse (TPR), and linear sweep voltammetry (LSV) were used to analyze the physical, chemical and photoelectrochemical characteristics of the as-synthesized photoanode. The results indicated that the Z-scheme heterojunction Bi2WO6/ZnO NRAs exhibited the excellent photocatalytic performance under sunlight irradiation as compared to pristine ZnO NRAs. Ergo, the PFC system achieved complete removal of COD and produced 3.30 μW cm−2, 37.10 μA cm−2 and 563 mV of maximum power density (Pmax ), short-current density (Jsc) and open-circuit voltage (Voc) within 4 h of sunlight irradiation, respectively. The boosted photoactivity was ascribed to the successful formation of the Z-scheme hybridization interface betwixt the Bi2WO6 and ZnO NRAs, that not only enhanced the visible light adsorption of ZnO NRAs, concomitantly significantly accelerated the spatial charge separation and restrained the electron-hole pair recombination.

Photocataytic Degradation of Phenol Using TiO2-Fe Under H2O2 Presence by Visible and Sunlight Irradiation

Phenol is one of the essential organic pollutants released into the environment because of its high stability and toxicity. It is harmful to organisms, environment, and posing a serious threat to human health at low concentration. This research investigated the photocatalytic degradation process of phenol using a TiO2-Fe catalyst under visible light irradiation and additional H2O2. The effect of various conditions process was applied, including different catalyst doses (0.2, 0.4, 0.6, and 0.8 g/L), pH (3, 6, 8, and 11), irradiation times (60, 90, 120, 150, and 210 minutes) and the presence of H2O2. The degradation process was studied at an initial concentration of phenol 5 mg/L. This study has been decreasing phenol content (90.51%) with catalyst doses 0.6 g/ L sample solution, pH solution 11, reaction time 210 minutes and H2O2 concentration 30%. This final phenol concentration after photodegradation under halogen light was 0.18 mg/L, while sunlight irradiation was 0.11 mg/L. This result is below government regulation as per Permen LH RI No. 5/2014 i.e. 0.5 mg/L. Therefore, this process possible to remove phenol in aqueous such as industrial wastewater or other resources.