Fabrication of Nano-Ag Encapsulated on ZnO/Fe₂V₄O₁₃ Hybrid-Heterojunction for Photodecomposition of Methyl Orange

Novel silver encapsulated nanocomposite zinc oxide/iron tetra-poly-vanadate (Ag-ZnO/Fe2V4O13) was synthesized with various wt% of silver (1.0–2.5 wt% of Ag) by cost-effective photo-deposition method under the irradiation of ultraviolet-A (UV-A) light. The nanostructure of the Ag-ZnO/Fe2V4O13 was explored by various characterization techniques. The surface functionalities were confirmed by Fourier transform infrared spectra and the crystalline nature of the material was revealed by X-ray diffraction patterns. Furthermore, the surface morphology and the optical properties of the composites were analyzed by scanning electron microscopy, energy dispersive X-ray–elemental color mapping (ECM), high-resolution transmission electron microscopy (HRTEM), ultraviolet–visible diffuse reflectance spectroscopy and photoluminescence. The crystallite size of Ag-ZnO/Fe2V4O13 was 28.5 nm which was consistent with HRTEM analysis. The photocatalytic activity was tested against aqueous methyl orange degradation under UV-A light irradiation. In all five runs, the stability of the catalyst was confirmed by reusability measurements and almost 98% of degradation was achieved. A suitable degradation pathway was proposed based on intermediates obtained during the degradation analyzed by gas chromatography–mass spectrometry. Trapping experiments confirmed that the superoxide radical anion (O2•−) was considered as the most active species for this degradation process. Complete mineralization was confirmed by the measurements of chemical oxygen demand

The surfactants mediated electropolymerized poly(aniline) (PANI)-reduced graphene oxide (rGO) composite counter electrode for dye-sensitized solar cell

In this work, poly(aniline) (PANI)-reduced graphene Oxide (rGO) low-cost nanocomposite used for counter electrode (CE) in dye-sensitized solar cells (DSSCs) for the replacement of the high-cost platinum (Pt) CE. The nanocomposite CEs were prepared with three different types of structural determine agents (cationic, non-ionic and anionic namely CTAB, Triton-X100, SDS) in aqueous medium and characterized by HR-SEM & TEM, XRD pattern analysis, FT-IR and Raman spectral studies. Electrochemical impedance spectroscopy (EIS) studies were used to determine the PANI-rGO-anionic surfactant in lower charge transfer resistance compared with, PANI, rGO and other type surfactants used in the preparation of CEs. DSSC assembled with a N719 dye sensitized TiO2 photo-anode, Poly(ethylene oxide) (PEO), iodide/triiodide redox couple containing electrolyte and PANI-rGO-anionic surfactant CE showed a sunlight-into-electrical energy conversion efficiency of 7.60%, which is higher than that of DSSC fabricated with pure Pt (6.40%), PANI (4.81%), rGO (4.30%) and PANI-rGO-CTAB (6.26%) and PANI-rGO-Triton X 100 (5.72%)

NiO@ZnO composite bimetallic nanocrystalline decorated TiO 2-CsPbI 3 photo-anode surface modifications for perovskite-sensitized solar cell applications

In this work, we fabricated a novel NiO@ZnO modification of TiO2-CsPbI3 photoanode-based Perovskite solar cells (PSCs). A facile hydrothermal synthesis is adopted for the preparation of NiO@ZnO-modified TiO2-CsPbI3 composite. The as-prepared NiO@ZnO modified TiO2-CsPbI3 composite is characterized by XRD, HR-TEM, SAED, FE-SEM with EDAX, AFM, XPS, FT-IR, UV-Vis, and Tauc plot analysis. UV-Vis spectra show that visible light absorption of the NiO@ZnO modified TiO2-CsPbI3 bilayer photoanode was more effective than NiO/ZnO modified TiO2-CsPbI3. XRD analysis showed the formation of NiO@ZnO in the TiO2-CsPbI3 in cubic crystalline nature. Morphological analyses were performed using FESEM, HRTEM, SAED, and AFM which revealed the formation of NiO@ZnO-modified TiO2-CsPbI3 with a multi-crystalline surface. EDAX and XPS analyses confirmed the presence of Ni, Zn, O, Ti, Cs, Pb, and I elements in the NiO@ZnO-modified TiO2-CsPbI3 composite. FT-IR spectra of perovskite metal oxide and hydroxide stretching vibrations peaks appeared at 920 and 3450 cm -1. The band gap was found to be 2.47 eV for NiO@ZnO-modified TiO2-CsPbI3 by using a Tauc plot. Finally, the photoanode-based PSCs were opti-mized by adding NiO@ZnO and TiO2-CsPbI3 composite, giving a high efficiency of 8.73%. We confirm that NiO@ZnO-modified TiO2-CsPbI3 bilayer photoanode-based PSCs show a better performance than NiO and ZnO-modified TiO2-CsPbI3.(c) 2022 Elsevier B.V. All rights reserved