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M-polynomial method for topological indices of 2D-lattice of three-layered single-walled titania nanotubes
摘要： A numeric number which represents a complete shape of the chemical graph is said to be the topological index. In this paper, we study the 2D-lattice of three-layered single-walled Titania nanotubes (SWTNT) and investigate their M-polynomial. Mainly, we compute the certain topological indices (TI’s) which relates to degree-based by the help of this M-polynomial. In addition, we give the first as well as second Zagreb polynomials of the aforesaid 2D-lattice nanotubes. At the end, we draw a comparison for the better understanding of the computed results.
关键词： topological indices,titania nanotubes,m-polynomial,2d-lattice
更新于2025-09-12 10:27:22
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Effect of Surface Modification on SILAR Deposited CdS Quantum Dot Sensitized Hydrothermally Synthesised Titania Nanostructure
摘要： In the present work titaniana noflakes-nanorods were prepared on a flexible titanium metal foil by modified hydrothermal method. The titania nanoflakes-nanorods were further sensitized with CdS quantum dots through SILAR deposition. The surface charge of the titania surfaces were tuned using triethanolamine (TEA) to obtain maximum loading of CdS particles on the surface. The samples were characterized by XRD, FE-SEM and EDX analysis, which confirms the enhanced deposition of CdS quantum dots on the titania surface by TEA modification. The visible light photocatalytic studies were done by methylene blue degradation study. The modification in the SILAR cycle using TEA improves the photocatlytic performance around 4 times than those without TEA. The OH.radical formed in the photocatalytic reaction followed by photoluminescence study.
关键词： SILAR,Photocatalysis,Triethanolamine,CdS quantum dot,Titania nanorod
更新于2025-09-12 10:27:22
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Size-Controlled Synthesis of Pt Particles on TiO2 Surface: Physicochemical Characteristic and Photocatalytic Activity
摘要： Different TiO2 photocatalysts, i.e., commercial samples (ST‐01 and P25 with minority of rutile phase), nanotubes, well‐crystallized faceted particles of decahedral shape and mesoporous spheres, were used as supports for deposition of Pt nanoparticles (NPs). Size‐controlled Pt NPs embedded in TiO2 were successfully prepared by microemulsion and wet‐impregnation methods. Obtained photocatalysts were characterized using XRD, TEM, X‐ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) specific surface area, DR/UV‐vis and action spectrum analysis. The effect of deposition method, amount of Pt precursor and TiO2 properties on size, distribution, and chemical states of deposited Pt NPs were investigated. Finally, the correlations between the physicochemical properties and photocatalytic activities in oxidation and reduction reactions under UV and Vis light of different Pt‐TiO2 photocatalysts were discussed. It was found that, regardless of preparation method, the photoactivity mainly depended on platinum and TiO2 morphology. In view of this, we claim that the tight control of NPs’ morphology allows us to design highly active materials with enhanced photocatalytic performance. Action spectrum analysis for the most active Pt‐modified TiO2 sample showed that visible light‐induced phenol oxidation is initiated by excitation of platinum surface plasmon, and photocatalytic activity analysis revealed that photoactivity depended strongly on morphology of the obtained Pt‐modified TiO2 photocatalysts.
关键词： titania morphology,microemulsion,platinum size,Pt‐TiO2,TiO2 particle size,heterogeneous photocatalysis
更新于2025-09-12 10:27:22
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Complementary Properties of Silver Nanoparticles on the Photovoltaic Performance of Titania Nanospheres Based Photoanode in Dye-Sensitized Solar Cells
摘要： In this study, the fabrication of photoanode of dye-sensitized solar cell using silver@titania nanospheres and N719 dye, and its enhanced photovoltaic performance in the dye-sensitized solar cell is described. Silver@titania with different mol. % of silver (1, 3 and 5 %) are synthesized using facile sol-gel and photochemical reduction method and are characterized by suitable analytical techniques. The synthesized nanocomposite materials showed nanospheres like morphology. Moreover, photoluminescence studies revealed that incorporation of silver nanoparticles on the titania nanospheres surface suppressed charge recombination process and which is more beneficial for dye-sensitized solar cells. Silver@titania nanospheres are successfully employed as a photoanode and demonstrated an enhanced solar-to-electrical energy conversion efficiency of 5.24 %, under full sun illumination (100 mW cm-2, AM 1.5 G) which is 30.67 % enhancement than that of bare titania nanospheres (4.01 %). This enhanced efficiency is attributed to the rapid interfacial charge transfer process and plasmonic effect offered by silver nanoparticles present in the silver@titania nanospheres. The improved charge transfer process led to minimize the back electron transfer reaction in the device. With complementary properties of silver nanoparticles, the high performance demonstrated by the silver@titania nanospheres could be an excellent candidate for the light energy harvesting applications.
关键词： Dye-sensitized solar cells,Plasmonic nanoparticles,Schottky barrier,Titania nanospheres,Silver nanoparticles
更新于2025-09-11 14:15:04
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Influence of Semiconductor Morphology on Photocatalytic Activity of Plasmonic Photocatalysts: Titanate Nanowires and Octahedral Anatase Nanoparticles
摘要： Octahedral anatase particles (OAP) with eight exposed and thermodynamically most stable (101) facets were prepared by an ultrasonication-hydrothermal (US-HT) reaction from potassium titanate nanowires (TNW). The precursor (TNW) and the product (OAP) of US-HT reaction were modi?ed with nanoparticles of noble metals (Au, Ag or Pt) by photodeposition. Samples were characterized by X-ray di?raction (XRD), X-ray photoelectron spectroscopy (XPS), di?use re?ectance spectroscopy (DRS), scanning transmission electron microscopy (STEM) and time-resolved microwave conductivity (TRMC). The photocatalytic activity was investigated in three reaction systems, i.e., anaerobic dehydrogenation of methanol and oxidative decomposition of acetic acid under UV/vis irradiation, and oxidation of 2-propanol under vis irradiation. It was found that hydrogen liberation correlated with work function of metals, and thus the most active were platinum-modi?ed samples. Photocatalytic activities of bare and modi?ed OAP samples were much higher than those of TNW samples, probably due to anatase presence, higher crystallinity and electron mobility in faceted NPs. Interestingly, noble metals showed di?erent in?uence on the activity depending on the semiconductor support, i.e., gold-modi?ed TNW and platinum-modi?ed OAP exhibited the highest activity for acetic acid decomposition, whereas silver- and gold-modi?ed samples were the most active under vis irradiation, respectively. It is proposed that the form of noble metal (metallic vs. oxidized) as well as the morphology (well-organized vs. uncontrolled) have a critical e?ect on the overall photocatalytic performance. TRMC analysis con?rmed that fast electron transfer to noble metal is a key factor for UV activity. It is proposed that the e?ciency of plasmonic photocatalysis (under vis irradiation) depends on the oxidation form of metal (zero-valent preferable), photoabsorption properties (broad localized surface plasmon resonance (LSPR)), kind of metal (silver) and counteraction of “hot” electrons back transfer to noble metal NPs (by controlled morphology and high crystallinity).
关键词： silver,platinum,gold,photocatalyst morphology,faceted titania,morphology-governed activity,plasmonic photocatalysis,octahedral particle,titanate nanowire,noble metal
更新于2025-09-11 14:15:04
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<i>In situ</i> fabrication of a direct <i>Z</i> -scheme photocatalyst by immobilizing CdS quantum dots in the channels of graphene-hybridized and supported mesoporous titanium nanocrystals for high photocatalytic performance under visible light
摘要： We report the considerable advantages of direct Z-scheme photocatalysts by immobilizing high-quality CdS quantum dots (QDs) in the channels of graphene-hybridized and supported mesoporous titania (GMT) nanocrystals (CdS@GMT/GR) under facile hydrothermal conditions. The photocatalysts have been characterized by XRD, PL, XPS, SEM, DRS, TEM, EIS, and N2 adsorption. CdS QDs primarily serve as photosensitizers with a unique pore-embedded structure for the e?ective utilization of the light source. This direct Z-scheme CdS@GMT/GR exhibits higher photocatalytic activity than CdS/GR, GMT/GR, or CdS@MT. In addition, the rate constant of CdS@GMT/GR-2 is approximately twice the sum of those of CdS@MT and GMT/GR, because GR played the role of hole-transporting and collection layer as well as the hybridization level formation in terms of hybridizing MT and serving as a support. Therefore, the GR content tunes the energy band, a?ects the surface area, and controls the interfacial hole transfer and collection rate of the direct Z-scheme system. Furthermore, CdS@GMT/GR retains its high performance in repeated photocatalytic processes. This can be attributed to the fact that GR prevents QDs from photocorrosion by means of the hole-transporting and collection e?ect. A possible reaction mechanism is proposed. This work provides a promising strategy for the construction of highly e?cient visible-light-driven photocatalysts to reduce the growing menace of environmental pollution.
关键词： environmental pollution,visible-light-driven photocatalysts,graphene-hybridized mesoporous titania,direct Z-scheme photocatalysts,CdS quantum dots
更新于2025-09-11 14:15:04
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Photocatalytic properties of TiO2 and Fe-doped TiO2 prepared by metal organic framework-mediated synthesis
摘要： The Ti-containing metal organic framework (MOF) MIL-125 has been used as sacrificial precursor to obtain TiO2 materials through the MOF-mediated synthesis route. In this study, Fe3+ was deposited on the surface of MIL-125 after its hydrothermal synthesis. Targeted Fe-doped titania photocatalysts were prepared through the direct calcination in air of Fe/MIL-125 crystals and/or by using a two-step method, including carbonization in inert atmosphere followed by calcination in air. The relationship between the synthesis conditions and the properties of the Fe-doped titania nanopowders, such as Fe content, porosity, phase composition and particle size was investigated. From elemental mapping, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, UV–Vis absorption spectroscopy and photoluminescence emission spectra, the presence of highly dispersed Fe3+ ions incorporated into the TiO2 crystal lattice was confirmed, which led to a significant red shift of photoresponse towards visible light and reduced the recombination rate of electron-hole pairs at low iron content. By varying the pre-carbonization temperature, both crystal size and phase composition in the final materials were modulated. The performance of Fe-doped titania materials in photocatalytic water-splitting was tested for hydrogen evolution. Optimal photocatalytic performance was found at 0.15 and 0.5 wt. % iron concentration and exceeded those of non-doped titania and commercial anatase both under visible and UV light irradiation, respectively, and among the highest reported in literature for these systems.
关键词： water splitting,Metal Organic Frameworks,H2 production,MOF-mediated synthesis,Fe-doped titania
更新于2025-09-11 14:15:04
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Modification of P25 titania in presence of hydrazine for <i>Staphylococcus aureus</i> inactivation
摘要： Titania and its polymorphs are one of the most studied semiconductor photocatalyst. Herein, the P25 titania was used as a precursor to modify the phase and structure with microwave assisted hydrothermal and sonochemical methods in presence of alkaline hydrazine. The outcome results show the cotton ball structure titanate composite phases (nanotubes, nanosheets and nanoparticles) and monoclinic titanate phase (TiO2-B) with microwave assisted hydrothermal method and sonochemical method, respectively. The nitrogen doping was confirmed by FTIR and DRS in modified TiO2. And some visible light absorption was observed in modified TiO2 due to the nitrogen doping. The composite phase titanate having cotton ball structure was found to be efficient for methicillin-resistant superbug Staphylococcus aureus (MRSA) inactivation. Herein, we also reported the submicron TiO2-B sword like morphology fabricated by sonochemical method for the first time in presence of alkaline hydrazine.
关键词： Bacterial inactivation,Titania,Sonochemical,Microwave assisted hydrothermal
更新于2025-09-10 09:29:36
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Microwave Assisted Synthesis, Modification With Platinum And Photocatalytical Properties of TiO2 Nanofibers
摘要： In the present work formation of active TiO2 nanoparticles in microwave synthesis and their modification with platinum were studied. Anatase nanopowder and 10 M KOH solution were used as raw materials. Microwave assisted synthesis method permited to obtain TiO2 nanofibres and nanowires with a diameter of 10 nm and a specific surface area in the range of 70 – 150 m2/g. In order to modify TiO2 nanofibers with platinum it was stirred in H2PtCl6 solution under UV irradiation. Photocatalytic activity was determined by degradation of the methylene blue (MB) solution under UV and visible light irradiation. The obtained samples showed higher photocatalytic activity with respect to pure TiO2 nanofibers. The doped TiO2 nanofibers were appropriate for degradation of harmful organic compounds as well as for hydrogen production by water splitting.
关键词： platinum,nanowires,titania nanofibers,anatase,photocatalysis
更新于2025-09-10 09:29:36
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Aryl–Aryl Coupling on Semiconductor Surfaces
摘要： Bottom-up strategies in nanotechnology offer unprecedented precision in fabrication of functional structures and devices. Soon after the advent of scanning probe microscopies in the 1980s, it was demonstrated that on-surface nanoobjects may be constructed at ultimate level of control—one atom at a time. Later on, it was shown that even a chemical reaction between two molecular entities is manageable in a stepwise fashion—all steps of a chemical reaction may be induced with scanning tip at will. The limits of precision have been reached. If one considers practical implementations, however, a major obstacle of tip-induced processes appears to be their tediousness. Alternative, fast, yet, precise routes to nanostructure formation are sought. In such a context non-locally induced procedures seem to be especially rewarding. There are, still, at least two expectations with regard to nonlocally induced chemical reactions. First, there is a need for a kind-of-trigger that will allow for a controlled activation of a given procedure. Second, it would be beneficial if the whole process is controllable by means of additional constraints, for example, a specific substrate may lead to a particular nanoobject morphology. An impressive example of such a strategy is aryl halide C–C coupling on surfaces allowing for construction of various 1D and 2D structures. In particular, when aryl halide C–C coupling is combined with cyclodehydrogenation reaction it facilitates synthesis of miscellaneous graphene derivatives, such as nanoribbons of different widths and diverse edge topology.
关键词： On-Surface Polymerization,Semiconductor Surfaces,Aryl–Aryl Coupling,Ge(001):H Surface,Rutile Titania
更新于2025-09-10 09:29:36