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Atomic-thick TiO <sub/>2</sub> (B) nanosheets decorated with ultrafine Co <sub/>3</sub> O <sub/>4</sub> nanocrystals as a highly efficient catalyst for lithium-oxygen battery
摘要： Development of high efficient catalysts based on transition metal oxides (TMOs) is desirable, and remains a big challenge for lithium-oxygen (Li-O2) batteries. In the present work, atomic-thick TiO2(B) nanosheets decorated with ultrafine Co3O4 nanocrystals (Co3O4-TiO2(B)) was synthesized and utilized as cathode catalyst in Li-O2 batteries by designing a hybrid and inducing oxygen vacancies. The XPS characterization results suggested that the introduction of Co3O4 nanocrystals could induce numerous oxygen vacancies in the TiO2(B) nanosheets through Co doping in the hybrid catalyst. The subsequent electrochemical experiments indicated that the Li-O2 batteries with the prepared hybrid catalysts showed high specific capacity (11000 mAhg-1), and good cycling stability (200 cycles at a limited capacity of 1000mAhg-1) with low polarization (above 2.7V for discharge medium voltage and below 4.0V for charge medium voltage within 80 cycles). Furthermore, a possible working mechanism was proposed for a better understanding of the high performance of Co3O4-TiO2(B) catalysts for the Li-O2 batteries. This work also provided some new insights into designing efficient catalysts through interface engineering between 2D (two dimentional) TMOs and 0D (zero dimentional) TMOs for Li-O2 batteries or other catalysis related fields.
关键词： film-like Li2O2,oxygen vacancies,TiO2(B) nanosheets,Co3O4 nanocrystals,Li-O2 battery
更新于2025-09-23 15:21:21
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Thermal and Photocatalytic Reactions of Methanol and Acetaldehyde on Pt-Modified Brookite TiO <sub/>2</sub> Nanorods
摘要： The influence of adding Pt on the catalytic and photocatalytic activity of monodispersed brookite phase TiO2 (B-TiO2) nanorods (NRs) was investigated. Pt was deposited on the NRs by photo-deposition in solution and the Pt-modified NRs were characterized using XPS, STEM, and LEIS. The thermal and photocatalytic activity of the Pt-modified NRs were then evaluated using temperature-programmed desorption (TPD) in ultra-high vacuum (UHV). It was found that while Pt primarily acted as a site blocker for thermal reactions, Pt also acted as a recombination center for photogenerated electrons and holes, resulting in suppressed photocatalytic activity. Upon pretreatment with O2, however, the Pt-modified NRs exhibited enhanced photoactivity, indicating that adsorbed oxygen prevents electron-hole recombination by reacting with photogenerated conduction band electrons from the B-TiO2 to produce stable superoxide species on the Pt surface deposits. These results clearly demonstrate how the dynamics of charge carriers at the oxide surface may be altered by metal deposits such as Pt, as well as by the presence of adsorbed species on the metal surface.
关键词： brookite,acetaldehyde,photo-oxidation,TiO2,TPD,UHV,methanol,Pt
更新于2025-09-23 15:21:21
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Defect-associated adsorption of monoethanolamine on TiO2(1 1 0): An alternative way to control the work function of oxide electrode
摘要： Controlling defects is one of the basic strategies for tailoring electronic structure of materials, which has not been explored that much yet for organic-inorganic hybrid systems. In this study, we investigated the control of work function of oxide electrode by defect-associated adsorption of molecules at the single-molecule level by means of scanning tunneling microscopy and first principle calculations. The equilibrium adsorption configuration of monoethanolamine (MEA, HO(CH2)2NH2), an effective coating for lowering the work function of an oxide electrode, varies as a function of surface coverage at TiO2(1 1 0) surfaces. Our results showed that defects at the oxide surface and intermolecular interactions dominate the stable configuration of adsorbates as well as work function of the system. The dissociative adsorption at Ov was found to be more efficient at lowering the work function of TiO2(1 1 0) surface, suggesting that defect control can be used to improve the performance of organic-inorganic hybrid systems.
关键词： STM,Work function,DFT,TiO2(1 1 0),Defect,Monoethanolamine
更新于2025-09-23 15:21:21
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Effect of dissolved silica on photocatalytic water purification with a TiO2 ceramic catalyst
摘要： If photocatalytic water purification technologies will find practical applications, the impact of total dissolved solids in the source water on the activity of the photocatalyst must be evaluated. In this study, we evaluated the effects of SiO3 2? in water on a TiO2 ceramic photocatalyst; specifically, we determined the effects of SiO3 2? on the rate of photocatalytic degradation of formic acid (as a model contaminant) and on the rate of photocatalytic inactivation of Escherichia coli in an aqueous solution. Both the rate of formic acid degradation and the sterilization rate decreased with increasing SiO3 2? concentration. On the other hand, at a given SiO3 2? concentration, the activity of the photocatalyst did not decrease over the course of 120 h, and the surface structure of the photocatalyst did not change (i.e., no precipitate formed on the surface). The decreases in photocatalytic activity due to the presence of SiO3 2? could be recovered by flushing the experimental apparatus with distilled water. These results show that the reason for the lower photocatalytic activity in the presence of SiO3 2? than in its absence was due to adsorption of SiO3 2? onto the surface of the TiO2 photocatalyst and that SiO3 2? adsorption was an equilibrium process in water.
关键词： TiO2 ceramic photocatalyst,SiO3 2?,Photocatalysis,formic acid,E. coli
更新于2025-09-23 15:21:21
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Engineering hierarchical porous oxygen-deficient TiO2 fibers decorated with BiOCl nanosheets for efficient photocatalysis
摘要： The hierarchical porous oxygen-deficient TiO2 (TiO2-δ) fibers decorated with BiOCl nanosheets, for the first time, were synthesized through a sol-gel method combined with centrifugal spinning, and subsequent heat treatment under steam. Therein, the byproduct water-soluble NaCl crystal was recycled and used as the self-manufactured and self-sacrificial template. The dissolving out of NaCl for the in situ preparation of BiOCl on the surface of TiO2-δ generates rich mesoporous fiber structure. The flower-like BiOCl nanosheets provide large surface area for the adsorption of reactants, and more light scattering/reflection channels for enhancing light absorption. A series of characterizations confirmed that the introduction of oxygen vacancies in TiO2 broadens the light response to visible range, and the promotion of charge separation due to the formation of p-n junction between BiOCl and TiO2-δ. As a result, the BiOCl/TiO2-δ fiber exhibits enhanced broadband photocatalytic performance in the degradation of reactive brilliant red and colorless phenol. The apparent reaction rate constant achieved by the optimized BiOCl/TiO2-δ composite (0.0636 min-1) far surpasses that of TiO2-δ fibers (0.0026 min-1) by a factor of 24 under visible light irradiation. The reactive species involved in photocatalysis were detected by scavenger experiments and electron spin resonance spectra. The possible charge transfer processes and mechanism were explored and discussed in detail. This work provides novel insight into the design and synthesis of broadband and effective heterostructure photocatalysts for practical wastewater treatment.
关键词： BiOCl,oxygen-deficient TiO2,p-n junction,broadband photocatalysis
更新于2025-09-23 15:21:21
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A Phosphonate Substituted Ruthenium(II) Bipyridyl Derivative as Photoelectrochemical Probe for Sensitive and Selective Detection of Mercury(II) in Biofluids
摘要： A ruthenium(II) bipyridyl derivative photoelectrochemical probe, Ru-1, is synthesized and coupled with TiO2 nanoparticles (Ru-1/TiO2) for the specific recognition and highly sensitive PEC detection of Hg2+ in a series of biofluids. The probe is designed with a chromophore, a thiocyanate recognition unit, a π-conjugated photoelectron transfer pathway, and a phosphonate anchor. TiO2 nanoparticles with strong affinity to phosphonate and suitable conduction band energy are used as intermediate layers to increase the Ru-1 adsorption amount and amplify the photocurrent response. Under irradiation, the Ru-1/TiO2/FTO with strong visible light harvesting capacity, aqueous stability and efficient photoelectron transfer, shows a high and stable photocurrent response. In the presence of Hg2+, however, the specific Hg2+ and NCS coordination changes the photophysical properties of Ru-1, imposing the probe with a wider band gap, a weaker absorbance, and a poorer photoelectron and hole separation efficiency, thus resulting in a significant photocurrent decrease. Based on the Hg2+ induced photocurrent change, the Ru-1/TiO2/FTO shows good selectivity and high sensitivity towards the PEC detection of Hg2+, with wide linear ranges from 10-12 to 10-7 and 10-7 to 10-3 g/mL, and a low limit of detection of 0.63 pg/mL. The PEC probe is recyclable and accurate for selective detection of Hg2+ in urine, serum and cell extracts. The whole analysis can be completed within 15 minutes. These good analytical performances indicate the PEC method might have great potential for the onsite detection of small molecules in bio-systems.
关键词： Hg2+ detection,photoelectrochemical probe,TiO2 nanoparticles,ruthenium(II) bipyridyl derivative,biofluids
更新于2025-09-23 15:21:21
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AIP Conference Proceedings [Author(s) PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON CURRENT PROGRESS IN MATHEMATICS AND SCIENCES 2017 (ISCPMS2017) - Bali, Indonesia (26–27 July 2017)] - Preparation and characterization of TiO2/BiVO4 composite: Can this photocatalyst, under visible light, be able to eliminate rhodamine B from water and why?
摘要： Bismuth vanadate (BiVO4) can be composited with titanium dioxide (TiO2) to obtain a photocatalyst that can be activated by visible light. Such photocatalyst may be operated by solar light, principally, a free photon source. Many researchers have been working hard to find a stable, efficient, and low cost photocatalytic systems. In this presentation, we will report our effort to prepare and characterize TiO2/BiVO4 composite, which is responsive under visible light. The TiO2/BiVO4 composite was prepared by co-precipitation method, in which the self-prepared TiO2 nanotubes was immersed in solution containing bismuth (III) and vanadate ions under certain pH. The freshly obtained TiO2/BiVO4 was dried and subjected to a heat treatment, then was characterized by XRD, UV-visible diffuse reflectance spectrophotometer, SEM, and photo-electro-chemical working station. The results showed a crystal phase mixture of TiO2/BiVO4 composite system, which are anatase (2θ of 27.5°, 36.1°, 54.3°) and monoclinic scheelite, bismuth vanadate (2θ of 19°, 29°). The photocurrent evolution under visible light exposure was investigated carefully. The results showed that the composite system is active under visible light, due to visible light absorption by narrow bandgap semiconductor, namely BiVO4. While the heterojunction system in TiO2/BiVO4 composite enhanced the separation of electron and charge, eventually, the electron would flow from the conduction band of BiVO4 to conduction band of TiO2, so the photocurrent will be enhanced. When this composite was being applied to the photoelectrocatalytic reactor system, containing aqueous rhodamine B, the enhancement of photo-catalytic degradation of rhodamine B was also significantly observed. The influence of bias potential applied during photoelectrocatalytic degradation process will be further discussed.
关键词： degradation rhodamine B,TiO2/BiVO4 composite,photocatalyst
更新于2025-09-23 15:21:21
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AIP Conference Proceedings [Author(s) PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON CURRENT PROGRESS IN MATHEMATICS AND SCIENCES 2017 (ISCPMS2017) - Bali, Indonesia (26–27 July 2017)] - Nickel sulfide sensitized TiO2 nanotubes system as photo-anode: Will this system active under visible light and why?
摘要： This work is dedicated to enhance the photo catalytic activity of the modified 2 nanotube under visible light exposure. The narrow band gap of semiconductor such as NiS can be incorporated onto TiO2 nanotube (NiS/TiO2-NT) to obtain a composite which may active under visible light. The TiO2 nanotube was self-prepared by electro-oxidation of titanium plate in electrolyte containing ethylene glycol, NH4F, and water. Meanwhile, the incorporation of NiS onto TiO2 film was prepared by successive ionic layer absorption and reaction (SILAR) method, in which nickel(II) ion and sulfide ion were used as the precursor of NiS, to obtain the NiS/TiO2-NT film system. The obtained NiS/TiO2-NT films were characterized by UVDRS, FTIR, SEM, XRD, and photo-electro-chemical work station. The resultsindicated that the peak of absorption spectra of NiS/TiO2-NT fall within thevisible light region, which the final band gap was 2.85 eV; IR and XRD spectra were also revealed the characteristic peak of NiS/TiO2-NT system. Photo-electrochemical investigation revealed that the evolution of photocurrent under visible light (100 W wolfram lamp), as much as 0.26 mA/cm2 typically can be easily observed.
关键词： photo-electrode,SILAR,NiS/TiO2
更新于2025-09-23 15:21:21
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Effect of metal doped and co-doped TiO2 photocatalysts oriented to degrade indoor/outdoor pollutants for air quality improvement. A kinetic and product study using acetaldehyde as probe molecule
摘要： This study demonstrates the photocatalytic decomposition of an indoor air pollutant, acetaldehyde (CH3CHO), over 0.04 mol% metal-doped TiO2 (Mn-, Co- and Mn/Co-) nanoparticles activated by ultraviolet and visible irradiation. The photocatalytic activity, the photodegradation kinetics, and the ?nal product analysis were examined using a Static Photochemical Reactor coupled with a FTIR spectrophotometer. CH3CHO undergoes ef?cient decomposition over all photocatalysts under UV irradiation in the presence of one atmosphere N2 or synthetic air (SA). Metal doping causes substantial in?uence to photocatalysis by altering the amount of electron/hole pairs generated and/or the electron/hole recombination rates. Simulating the experimental results with pseudo-?rst order kinetics the corresponding degradation rate coe?cients were determined for each photocatalyst under UV irradiation and SA environment: kd UV(Mn-TiO2) = (1.9 ± 0.2)×10 ?1 h ?1, kd UV(Co-TiO2) = (2.8 ± 0.3)×10 ?1 h ?1, and kd UV(Mn/Co-TiO2) = (6.0 ± 0.7)×10 ?1 h ?1. These degradation kinetics under UV light irradiation are signi?cantly faster than undoped TiO2 revealing that the transition metal doping of TiO2 nanomaterials boosts the photocatalytic degradation of organic pollutants. Substantial decomposition of CH3CHO was achieved under visible light in the presence of oxygen over Mn-TiO2 with kd Vis(SA) = (0.44 ± 0.04)×10 ?1 h ?1 while for other samples no visible light photocatalysis was observed. CO2, CO, and H2O were the main oxidation products, with CO2 yields almost 100% under UV excitation, and CO yields up to 20% under UV and < 1% under visible excitation. Our experimental results suggest that Mn-TiO2 (0.04 mol%) nanoparticles may be considered as a potentially safe photocatalyst to remove acetaldehyde particularly from indoor atmospheric environments under visible irradiation, without yielding signi?cant toxic by-products. Other possible atmospheric implications are also discussed in the paper.
关键词： Metal-doped TiO2,Visible-ultraviolet photocatalysis,Photodegradation kinetics,Acetaldehyde,Indoor air pollution
更新于2025-09-23 15:21:21
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Pd/TiO <sub/>2</sub> -Photocatalyzed Self-Condensation of Primary Amines To Afford Secondary Amines at Ambient Temperature
摘要： Symmetric secondary amines were synthesized by the self-condensation of primary amines over a palladium-loaded titanium dioxide (Pd/TiO2) photocatalyst. The reactions a?orded a series of secondary amines in moderate to excellent isolated yields at ambient temperature (30 °C, in cyclopentyl methyl ether). Applicability for one-pot pharmaceutical synthesis was demonstrated by a photocatalytic reaction sequence of self-condensation of an amine followed by N-alkylation of the resulting secondary amine with an alcohol.
关键词： secondary amines,Pd/TiO2,self-condensation,primary amines,photocatalysis
更新于2025-09-23 15:21:21