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Surface defect and rational design of TiO2?x nanobelts/ g-C3N4 nanosheets/ CdS quantum dots?hierarchical structure for enhanced visible-light-driven photocatalysis
摘要： TiO2-x/g-C3N4/CdS ternary heterojunctions are fabricated through thermal polymerization-chemical bath deposition combined with in-situ solid-state chemical reduction approach. The prepared materials are characterized by X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption, and X-ray photoelectron spectroscopy. The results show that the ternary heterojunctions are formed successfully and CdS quantum dots (QDs) and TiO2 are anchored on surface of g-C3N4 nanosheets simultaneously. The visible-light-driven photocatalytic degradation ratio of Bisphenol A and hydrogen production rate are up to 95% and ~254.8 mmol h-1, respectively, which are several times higher than that of pristine TiO2. The excellent visible-light-driven photocatalytic activity can be ascribed to the synergistic effect of TiO2-x, g-C3N4 and CdS QDs which extend the photoresponse to visible light region and favor the spatial separation of photogenerated charge carriers.
关键词： Photocatalysis,Ti3+ self-doping,g-C3N4 nanosheets,CdS quantum dots,TiO2 nanobelts
更新于2025-09-04 15:30:14
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Stability study of natural green dye based DSSC
摘要： Evolution of solar cell based on natural molecules flourished expeditiously, which is a good alternative for silicon-based solar cells or thin film technologies due to their low assembling cost, lightweight and flexibility. But natural dye-based dye-sensitized solar cell (DSSC) has low cell efficiency and stability, which limits the use of organic solar cells. In this research, natural green dye extracted from spinach (Spinacia oleracea) and used as a sensitizer source for natural dye-based DSSC. The measured cell efficiency of natural green dye-sensitized DSSC was 0.398%. Also, the cell stability test has been carried out by measuring the degradation rate (cell efficiency) by aging the dye molecule for DSSC has been conducted after 48, 96, 144 and 196 hours under 100mW/cm2 illumination (1.5 AM) at the ambient condition.
关键词： natural green dye,degradation,DSSC,chlorophyll,TiO2,stability
更新于2025-09-04 15:30:14
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Enhanced photocatalytic characteristics by Ag-sensitized TiO2 photocatalysts with mixed phases
摘要： The Ag-sensitized TiO2 photocatalysts with various contents of Ag were fabricated by a facile sol-gel method. The Ag nanoparticles with an average diameter of only a few nanometers distributed uniformly over the TiO2 surface. Their presence resulted in suppressed recombination and more effective utilization of the visible-light radiation through surface plasmon resonance. However, excess Ag nanoparticles led to higher recombination rates, reduced surface area, and thereby lower photocatalytic activity. Comparative study on the photocatalytic performance of the photocatalysts without and with various Ag loadings was systematically carried out. The moderate reduction of Ag nanoparticles by an appropriate surface treatment condition to increase the area for dye adsorption was favorable to photodegradation. By double calcinations, mixed phases of anatase and rutile were obtained, which exhibited better performance than single phase. The synergistic effect of Ag nanoparticles, mixed phase TiO2 and high surface area has qualified the Ag-sensitized TiO2 nanocomposites as highly promising photocatalysts.
关键词： Calcination,Photodegradation,Ag-sensitized,TiO2,Ag decoration,Mixed phases
更新于2025-09-04 15:30:14
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Alkaline Hydrothermal Synthesis, Characterization, and Photocatalytic Activity of TiO <sub/>2</sub> Nanostructures: The Effect of Initial TiO <sub/>2</sub> Phase
摘要： One-dimensional (1D) titanate nanostructures were synthesized by hydrothermal route, using commercially available TiO2 (P25) and anatase powders as precursor materials and strong NaOH solution as catalyzer. The prepared titanates were calcined, followed by protonation to produce TiO2 nanostructures having enhanced photocatalytic and photovoltaic properties. The synthesized TiO2 1D nanostructures were characterized using field-emission scanning electron microscope, high-resolution electron microscope, X-ray diffraction analysis, and UV-Vis photospectroscopy to understand the effect of initial TiO2 phase on morphological and crystallographic features, and bandgap. Methylene blue degradation test was applied to evaluate the photoactivity of the products obtained after different stages of the process. The findings indicate that 1D TiO2 nanostructures form by different mechanisms from dissolved aggregates during hydrothermal process, depending on the crystal structure of the initial precursor used. Photocatalytic test results reveal that protonated titanates have considerable adsorption capability, while photocatalytic degradation depends on TiO2 transformation.
关键词： TiO2,Photocatalytic Activity,1D Structure,Hydrothermal Process,Nanoribbons
更新于2025-09-04 15:30:14
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Preparation of TiO2/Fe2O3/Chitosan Nanocomposite Films and Its Photocatalytic Degradation of Rhodamine B
摘要： A new photocatalytic thin films TiO2/Fe2O3/chitosan was synthesized by a solution casting technology to degrade the azo coloured compounds in the industrial waste water. The prepared TiO2/Fe2O3/chitosan was characterized by X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy (HRTEM). TiO2 and Fe2O3 were entrpped in the chitosan film uniformly. The catalytic ability of TiO2/Fe2O3/chitosan was evaluated by photodegradtion of Rhodamine B. About 99.4 % Rhodamine B were photodegraded by 0.5 g L-1 photocatalyst under solar lights irradiation for 120 min. The influence of the reaction pH has been well investigated. And TiO2/Fe2O3/chitosan has good stability and reusability, it is suitable for the practical industrial waste water treatment.
关键词： Photocatalytic degradation,Chitosan,Fe2O3,TiO2
更新于2025-09-04 15:30:14
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Bandgap Tailored TiO2 Thin Films by Addition of SiO2 for Enhanced Photocatalytic Activity against Congo Red under Visible Light Illumination
摘要： Colloidal solutions of SiO2-TiO2 mixed oxides having different SiO2 contents were synthesized by sol-gel technique and thin films were deposited over glass slides by using dip coating technique. The films were subjected to high temperature at 400 °C for growing TiO2 crystals. Energy dispersive X-ray spectroscopy was used to indicate the elements in the films. X-ray diffraction analysis indicated that SiO2-TiO2 films contain only anatase phase. Scanning electron microscopy was used to study the films surface morphology. The SiO2-TiO2 films that were contacted with congo red (5 ppm) and irradiated with visible light showed a high photocatalytic activity. UV spectrophotometry technique was used to monitor the degradation of congo red by the reduction of main absorbance peak at 497 nm. Complete degradation was achieved after 2 h for 3 mol % SiO2-TiO2 thin film.
关键词： Congo red,SiO2,Dip coating,TiO2,Photocatalytic activity
更新于2025-09-04 15:30:14
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Electrolyte Factors Influencing Separated Pore Growth of Anodic TiO2 Nanotube Arrays
摘要： This work presents an investigation of electrolyte properties in relation to the growth of TiO2 nanotube array films, particularly concerning the measurement of conductivity in the diethylene glycol-hydrofluoric-water electrolyte system. The work aims to elucidate the behavior of ions in the anodized electrolytes with a better insight into the relation between molar conductivity and concentration of the additives. Differing solvation of the fluoride ion in various composition of water in the DEG-H2O mixture is attributed to the major factor determining the capability of proton transfer, controlling the ionic mobilities and the molar conductivities. Applying the feature of the two-factorial experiment has demonstrated a clear interaction of electrolyte parameters and titanium concentration dissolving into the electrolyte, which is believed to be a combination effect on pore widening and separating of nanotubes. A proposed schematic drawing has been demonstrated, summarizing how the nanotube arrays are constructed as a consequence of varying electrolyte type and composition.
关键词： electrochemical anodization,tube separation,TiO2 nanotube arrays,electrolyte conductivity
更新于2025-09-04 15:30:14
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3D heterostructured Ti-based Bi2MoO6/Pd/TiO2 Photocatalysts for High-Efficiency Solar Light Driven Photoelectrocatalytic Hydrogen Generation
摘要： Hydrogen fuel generation using solar light via photoelectrochemical (PEC) methods can help meet growing global energy demands and decrease environmental pollution. The key to efficient PEC hydrogen production is the synthesis of solar light driven photoelectrodes with efficient charge carrier separation. Here, we designed and prepared a ternary Bi2MoO6/Pd/TiO2 photoelectrode composed of Bi2MoO6 nanosheets, Pd nanoparticles (NPs) and TiO2 nanotube arrays (NTAs) on a Ti substrate using electrochemical methods. This novel photoelectrode had good visible light absorbance and significantly improved PEC hydrogen production rates (~5 and > 15 times higher under UV-vis and visible light irradiation, respectively, compared with TiO2 NTAs). The interfacial charge transfer mechanism of Bi2MoO6/Pd/TiO2 NTAs was comprehensively studied by comparing its PEC and photoelectrocatalytic performance with other TiO2 NTAs (i.e. Pd/TiO2 NTAs, Bi2MoO6/TiO2 NTAs and Pd/Bi2MoO6/TiO2 NTAs). For Bi2MoO6/Pd/TiO2 NTAs, Pd NPs homogeneously dispersed across the inside and outside of TiO2 nanotube walls helped to tightly anchor Bi2MoO6 nanosheets onto the TiO2 surface, forming a ternary 3D heterostructure. This structure facilitated interfacial electron injection from Bi2MoO6 to TiO2, accelerating the separation of the photogenerated electron-hole pairs. And significantly enhanced the photocurrent response and hydrogen production rate were achieved compared with other TiO2 NTAs. This 3D ternary semiconductor/metal/semiconductor heterojunction provides a viable approach for designing and synthesizing highly efficient novel photocatalysts that can effectively utilize solar energy.
关键词： TiO2 nanotube arrays,Pd nanoparticles,Bi2MoO6 nanosheets,Photoelectrocatalytic hydrogen production,Ternary photocatalyst
更新于2025-09-04 15:30:14
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Ethiopian natural zeolites for photocatalysis
摘要： The combination of zeolites and photochemistry has recently shown excellent results due to the special structure of the zeolites that helps a better use of the solar energy improving the selectivity of the chemical reactions carried out. There are several reports on the preparation of TiO2 confined nanoparticles in synthetic zeolites. However, very few reports are found on the use of natural zeolites. Zeolites are a vast natural resource in Ethiopia that remains unexploited. Their microporous structure can accommodate a wide variety of cations such as sodium, potassium and magnesium among others. The main objective of our work was to test the potential use of the naturally occurring zeolites, with high content in titanium, as photocatalysts. The samples have been characterized by X-ray diffraction (XRD), chemical analysis (ICP-OES), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV-Vis) and photocatalytic activities of the samples were tested in photocatalytic degradation of methyl orange (MO).
关键词： Natural zeolite,Photocatalysis,Methyl orange,Band gap energy,TiO2 loading
更新于2025-09-04 15:30:14
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Photoelectrochemically Active N‐Adsorbing Ultrathin TiO <sub/>2</sub> Layers for Water‐Splitting Applications Prepared by Pyrolysis of Oleic Acid on Iron Oxide Nanoparticle Surfaces under Nitrogen Environment
摘要： Highly performing photocatalytic surfaces are nowadays highly desirable in energy fields, mainly due to their applicability as photo water-splitting electrodes. One of the current challenges in this field is the production of highly controllable and efficient photoactive surfaces on many substrates. Atomic layer deposition has allowed the deposition of photoactive TiO2 layers over wide range of materials and surfaces. However, nitrogen doping of the growing layers, a highly effective way of controlling the absorption edges of photoactive surfaced, is still a challenging task. Here, the preparation of hierarchical nanostructured surfaces based on Langmuir–Schaefer and atomic layer deposition is proposed. Ultrathin TiO2 layers that are photoelectrochemically active in water splitting are prepared by a relatively low-temperature catalytic decomposition of oleic acid capping layers of iron oxide nanoparticles and the posterior nitrogen adsorption. The results evidence that simple N-adsorption is sufficient to narrow the bandgap of TiO2 layers that is equal to bandgap narrowing (0.12 eV) observed for substitutionally N-doped materials. The photocatalytic activity tests of the prepared surfaces in water-splitting applications demonstrate ≈90% increase in the activity of the N-adsorbing TiO2 layers.
关键词： Langmuir–Schaefer,magnetite (Fe3O4),photocatalysis,titanium dioxide (TiO2),atomic layer deposition (ALD)
更新于2025-09-04 15:30:14