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PHOTOCATALYTIC REMOVAL OF PHENOL OVER MESOPOROUS ZnO/TiO2 COMPOSITES
摘要： A series of mesoporous ZnO/TiO2 composites were successfully synthesized using cetyltrimethylammonium bromide surfactant. The composites of different Zn:Ti molar ratios (0.5:1, 0.75:1, and 1:1) were prepared by impregnating ZnO onto mesoporous TiO2. XRD results verified co-existence of both anatase TiO2 and hexagonal wurtzite ZnO in the ZnO/TiO2 composites. Based on the Tauc plots, all the composites showed almost the same band gap energy of approximately 3.21 eV. The fourier transform infrared spectroscopy results successful covering of ZnO on the surface of the TiO2 as the hydrophilicity property of TiO2 decreased remarkably with the loading of ZnO in the composites. N2 adsorption-desorption isotherms of the samples exhibited type-IV isotherm with a hysteresis loop. The Barrett-Joyner-Halenda pore size distribution revealed that the average pore size of the composites was around 3.6 nm, indicating the formation of mesopores dominantly in the samples. The photocatalytic removal of phenol over the samples under UV light irradiation after 3 h decreased in the order: ZnO/TiO2 composites > anatase TiO2 (with surfactant) > anatase TiO2 (without surfactant) > ZnO. The composite with Zn:Ti molar ratio of 0.75:1 has achieved the highest photocatalytic activity of 36.5% in the removal of phenol under UV light irradiation for 3 h.
关键词： photocatalytic activity,ZnO/TiO2 composites,phenol,ZnO,TiO2
更新于2025-09-23 15:21:01
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Cascade Structured ZnO/TiO2/CdS quantum dot sensitized solar cell
摘要： Cascade structure of ZnO/TiO2/CdS quantum dot sensitized solar cell (QDSSC) using precursor solutions of CdS quantum dots having different concentrations such as 0.1 M, 0.2 M, 0.5 M and 0.8 M were synthesized on fluorine doped tin oxide (FTO) substrate, using the successive ionic layer absorption and reaction (SILAR) method. A polysulfide electrolyte was used as a redox mediator. The combination of ZnO/TiO2 used as a photoanode gives the best results and changes the mechanism of the QDSSC. The conventional Pt counter electrode was replaced by a low cost CuS counter electrode. Morphological and structural characterizations were carried out by field-emission scanning electron microscope (FESEM) & X-ray diffractometer, respectively. The optical characterizations were carried out by using ultraviolet–visible (UV–Vis) spectroscopy. Degree of porosity of prepared quantum dot (QD) sensitizers on TiO2/ZnO surface of different precursor concentrations 48.90%, 45.90%, 44.20% and 42.41% were observed. J-V characteristics and the performance of the prototype solar cell devices were evaluated by using a solar simulator, under illumination with an AM 1.5G spectrum having light intensity of 100 mWcm?2. The highest efficiency was obtained 2.44% at 0.1 M concentration and the lowest was 0.52% at 0.8 M concentration.
关键词： Quantum dot sensitized solar cell,ZnO/TiO2/CdS,Counter electrode
更新于2025-09-23 15:21:01
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Thin Film of TiO <sub/>2</sub> a??ZnO Binary Mixed Nanoparticles as Electron Transport Layers in Low-Temperature Processed Perovskite Solar Cells
摘要： Organic–inorganic hybrid perovskite solar cells have become one of the highly promising candidates for photovoltaic technologies because of their low processing cost, rapid-growing power conversion efficiency and easy preparation process. Electron transfer layer (ETL) plays an important role in exciton separation and charge transport for perovskite devices. A TiO2–ZnO binary mixed nanoparticle (NP) ETL, which can be prepared in low-temperature hydrothermal method, was proposed. By analyzing the XRD and SEM, the incorporation of mixed NPs thin film improved the interfacial stability of ZnO/perovskite and prevented the perovskite layer from being decomposed as compared to the pure ZnO NPs thin film. Furthermore, UV spectrum and EIS results show that TiO2–ZnO mixed NP ETL has high transmittance and maintains good electrical properties of pure ZnO NPs basically. Finally, the efficiency of perovskite device based on TiO2–ZnO mixed NP ETL was improved to 15%. Our research provides a simple way for the application of ZnO in PCSs.
关键词： Perovskite solar cells,electron transport layers,ZnO,TiO2,low temperature
更新于2025-09-23 15:19:57
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Photocatalytic decontamination of phenol and petrochemical wastewater through ZnO/TiO <sub/>2</sub> decorated on reduced graphene oxide nanocomposite: influential operating factors, mechanism, and electrical energy consumption
摘要： ZnO/TiO2 anchored on a reduced graphene oxide (rGO) ternary nanocomposite heterojunction was synthesized via the multi-step method including hydrothermal, solvothermal and sol–gel methods. XRD, Raman, FESEM, EDX, Dot Mapping EDS, BET, FTIR, UV-VIS, TGA, and EIS techniques were utilized for characterizing as-synthesized catalysts. The XRD and Raman data proved the formation of anatase phase TiO2 and wurtzite phase ZnO in the prepared samples. Further, the UV-Vis spectrum confirmed that the band gap value of ZnO/TiO2 diminished on introduction of graphene oxide. Photocatalytic performance of the fabricated catalysts was investigated by decontamination of phenol in aqueous solutions. The effect of different operational factors such as pH, catalyst dosage, phenol concentration, and light illumination was investigated to find the optimum decontamination conditions. According to the results, complete degradation of phenol was achieved at pH = 4, catalyst dosage of 0.6 g L?1, light intensity of 150 W, and phenol initial concentration of 60 ppm at 160 min under visible light illumination. With the addition of graphene oxide to the composite, a significant increase was detected in the photocatalytic performance due to the higher available surface area and lower electron/hole recombination rate. In addition, the scavenging experiments revealed that the ?OH is responsible for the degradation of phenol during the reaction. The degradation mechanism, economic performance, mineralization, and recyclability were also investigated. Kinetic studies confirmed that photocatalytic degradation process followed the pseudo-first-order kinetic model. A case of real wastewater treatment was used to examine the performance of the catalyst for real case studies.
关键词： Phenol degradation,Nanocomposite,Wastewater treatment,Photocatalysis,ZnO/TiO2,Reduced graphene oxide
更新于2025-09-19 17:15:36
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Highly efficient planar heterojunction perovskite solar cells with sequentially dip-coated deposited perovskite layers from a non-halide aqueous lead precursor
摘要： High-performance planar heterojunction (PHJ) perovskite solar cells (PrSCs) with MAPbI3 perovskite films were fabricated using a facile, environmentally benign, efficient and low-cost dip-coating deposition approach on a bilayered ZnO/TiO2 electron transport system from aqueous non-halide Pb(NO3)2. Outstanding performance of PrSCs was achieved due to the PHJ configuration of FTO/TiO2/ZnO/MAPbI3/spiro-OMeTAD/MoO3/Ag. These PHJ PrSCs exhibited better performance and stability with thinner ZnO layers in contrast to those with mesoporous TiO2 scaffolds, indicating that the thickness of the ZnO layer in the PHJ architecture significantly affected the surface coverage, morphology, crystallinity, and stability of the MAPbI3 perovskite films processed by dip-coating deposition.
关键词： ZnO/TiO2 electron transport system,perovskite solar cells,planar heterojunction,dip-coating deposition,aqueous non-halide Pb(NO3)2
更新于2025-09-19 17:13:59
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Enhanced Electrochemical Stability of TiO <sub/>2</sub> -Protected, Al-doped ZnO Transparent Conducting Oxide Synthesized by Atomic Layer Deposition
摘要： Transparent, conductive coatings on porous, three-dimensional materials are often used as the current collector for photoelectrode designs in photoelectrochemical applications. These structures allow for improved light trapping and absorption in chemically-synthesized, photoactive overlayers while minimizing parasitic absorption in the current collecting layer. Atomic layer deposition (ALD) is particularly useful for fabricating transparent conducting oxides (TCOs) like Sn-doped In2O3 (ITO) and Al-doped ZnO (AZO) for structured materials because the deposition is specific to exposed surfaces. Unlike line-of-site deposition methods (evaporation, spray pyrolysis, sputtering), ALD can access the entire complex interface to make a conformal transparent conductive layer. While ITO and AZO can be grown by ALD, they are intrinsically soluble in the acidic and basic environments common for electrochemical applications like water splitting. To take advantage of the unique characteristics of ALD in these applications, is important to develop strategies for fabricating TCO layers with enhanced chemical stability. Ultra-thin coatings of stable materials can be used to protect otherwise unstable electrochemical interfaces while maintaining the desired function. Here, we describe experiments to characterize the chemical and electrochemical stability of ALD-deposited AZO TCO thin films protected by a 10nm TiO2 overlayer. The addition of a TiO2 protection layer is demonstrated to improve the chemical stability of AZO by orders of magnitude compared to unprotected, yet otherwise identically prepared AZO films. The electrochemical stability is enhanced accordingly in both acidic and basic environments. We demonstrate that TiO2-protected AZO can be used as a TCO for both the cathodic hydrogen evolution (HER) and anodic water oxidation (OER) half-reactions of electrochemical water splitting in base and for HER in acid when the appropriate electrocatalysts are added. As a result, we show that ALD can be used to synthesize a chemically stable TCO heterostructure, expanding the range of materials and electrochemical environments available for building complex photoelectrode architectures.
关键词： Water splitting,Transparent conducting oxides,Atomic layer deposition,Electrochemical stability,Al-doped ZnO,TiO2 protection layer
更新于2025-09-10 09:29:36