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From micro to macro-contaminants: The impact of low-energy titanium dioxide photocatalysis followed by filtration on the mitigation of drinking water organics
摘要： This study evaluated strategies targeting macro- and micro-organic contaminant mitigation using low-energy titanium dioxide photocatalysis. Energy inputs of 1, 2, and 5 kWh m-3 resulted in incomplete oxidation of macro-organic natural organic matter, signified by greater reductions of UV254 and specific ultraviolet UV absorbance (SUVA) in comparison to dissolved organic carbon (DOC). The rate of UV254 removal was 3 orders of magnitude greater than the rate of DOC degradation. Incomplete oxidation improved operation of downstream filtration processes. Photocatalysis at 2 kWh m-3 increased the bed life of downstream granular activated carbon (GAC) filter by 340% relative to direct filtration pretreatment. Likewise, photocatalysis operated ahead of microfiltration decreased fouling, resulting in longer filter run times. Using 2 kWh m-3 photocatalysis increased filter run time by 36 times in comparison to direct filtration. Furthermore, levels of DOC and UV254 in the membrane permeate improved (with no change in removal across the membrane) using low-energy photocatalysis pretreatments. While high-energy UV inputs provided high levels of removal of the estrogenic micro-organics estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethynlestradiol (EE2), low-energy photocatalysis did not enhance removal of estrogens beyond levels achieved by photolysis alone. In the cases of E1 and E3, the addition of TiO2 as a photocatalyst reduced degradation rates of estrogens compared to UV photolysis. Overall, process electrical energy per order magnitude reductions (EEOs) greatly improved using photocatalysis, versus photolysis, for the macro-organics DOC, UV254, and SUVA; however, energy required for removal of estrogens was similar between photolysis and photocatalysis.
关键词： granular activated carbon (GAC),estrogens,UV photolysis,dissolved organic carbon (DOC),advanced oxidation process (AOP),natural organic matter (NOM)
更新于2025-09-23 15:21:01
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Enhanced hole transport in benzoic acid doped spiro-OMeTAD composite layer with intergrowing benzoate phase for perovskite solar cells
摘要： Spiro-OMeTAD is one of the widely used hole-transfer materials for designing high-performance perovskite solar cells. It is reported that acid doping is an efficient and facile method to increase the conductivity of spiro-OMeTAD and accelerate its oxidation process. Besides, investigating the morphologic controlling mechanism of spiro-OMeTAD films would give a novel insight in designing the hole-transport layer (HTL) and further clarify the mechanism of acid additives. In this work, the effect of benzoic acid on the spiro-OMeTAD oxidation is studied, where the formation of the lithium benzoate phase can decrease the size of hollows in the spiro-OMeTAD film. By doping benzoic acid, the HTL exhibits faster oxidation process and better hole transfer ability. Meanwhile, the hysteresis of the perovskite solar device based on the HTL is effectively reduced via optimizing the doping content, with an improved power conversion efficiency reaching up to 16.26% under standard AM 1.5G illumination.
关键词： Benzoic acid,Perovskite solar cells,Hole-transport layer,Oxidation of spiro-OMeTAD
更新于2025-09-23 15:21:01
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Ti, Zn co-doped hematite photoanode for solar driven photoelectrochemical water oxidation
摘要： Although there have been many reports of metal doping to ameliorate the drawbacks of hematite as the photoanode for water oxidation, most of them focused on monometallic doping, and only a few of them payed attention to bimetallic doping. What is worse, the synergetic mechanism between two metal dopants was not su?ciently studied, especially the density functional theory (DFT) calculation. In this work, the n-type hematite was synthesized by introducing Ti dopant into hematite through the hydrothermal method, and dipping-sintering treatment was employed to further introduce homogeneously dispersed Zn dopant into that, forming the Ti, Zn co-doped hematite. Under the optimal condition, Ti-doped hematite photoanode reached approximately 2-times enhancement of the photocurrent density compared with the pristine one at 1.23 V vs. RHE, while Ti, Zn co-doped hematite anode obtained another 25% elevation. UV –Vis spectroscopy, Mott –Schottky plots, EIS analysis, photo-oxidation of hole scavenger (H 2 O 2 ), and DFT calculation were employed to understand the role of Ti, Zn dopant. Based on the obtained results, the synergetic mechanism of two dopants was discussed, i.e., the improvement of PEC performance of Ti, Zn co-doped hematite photoanode was possibly attributed to greater carrier density and improved charge separation e?ciency at the surface of hematite. This work provides new strategy and understanding of the improvement of PEC performance of hematite by doping engineering.
关键词： Photoelectrochemical water oxidation,Zn co-doping,Ti,DFT calculation,Hematite
更新于2025-09-23 15:21:01
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The effects of growth TiO <sub/>2</sub> nanotubes on forged Ti <sub/>6</sub> Al <sub/>4</sub> V alloy and selectivelaser sintered Ti <sub/>6</sub> Al <sub/>4</sub> V alloy surfaces for environment and medical applications
摘要： The paper describes the effect of growth TiO2 nanotubes on titanium surfaces by anodic oxidation for environmental and medical applications. The importance of the metallurgical state of TiAl6V alloy on the growing of TiO2 nanotubes by anodization will be highlighted. Starting from the possibility of obtaining the TiO2 nanotubes, the paper presents results on TiO2 nanotubes grown by electrochemical anodization method, using a solution containing HF 0,4% and having as electrodes, graphite as cathode and titanium alloy specimens obtained by two technologies: by cold plastic deformation as well as by additive manufacturing process SLS, as anode. So, the nanotubes were produced by anodization and analysed by scanning electron microscopy. The aim of this paper is to compare the electrochemical formation of TiO2 on the surface of both specimens knowing that the titanium alloys and its oxides are used in many biomedical and environmental applications, thus providing the importance of nanotubes and the fact that their properties open doors in these fields.
关键词： medical applications,TiO2 nanotubes,environmental applications,anodic oxidation,Ti6Al4V alloy
更新于2025-09-23 15:21:01
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Laser printing of micro-electronic communication systems for smart implants applications
摘要： Endow the implant with intrinsic communication system between sensors and actuators or between implant and patient is a key factor for its long-term success. The capacity of early diagnosis of failures and the ability to remedy them are necessary to minimize expensive complications and reducing revision procedures. Ti6Al4V is the most used titanium alloy for implant’s fabrication. In this sense, this work presents a promising approach to print communication systems by using laser technology, aiming integrate the smart components on titanium implants. Laser has been employed as a versatile tool to modify the surface in different ways, such as texturing, oxidizing and sintering. Silver wires have been printed on Ti6Al4V surface in order to conduct electrical current. To minimize current loss for the substrate, titanium oxide layer has been produced by different methods (laser and anodization). Laser sintering (LS) has been also compared to a conventional method (Hot-pressing- HP) to consolidate the silver powder into the cavities. In comparison to the conventional techniques, laser demonstrated to be a competitive approach to oxidizing the surface and also for consolidating the micro-wires on Ti6Al4V surface. Consequently, the micro-wires printed by laser approach presented satisfactory results in terms of electrical resistance, actuating as the conductor path for electrical current, with values of 0.0131 Ω, which is similar to the resistance of the wire printed in an insulator substrate.
关键词： Ti6Al4V titanium alloy,Laser oxidation,Implants,Laser surface modification,Nd:YAG laser,Laser sintering
更新于2025-09-23 15:21:01
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9-Fluorenone as Photocatalyst for the Oxidation of Alcohols with Air
摘要： Das and co-workers report a visible light-induced oxidation of alcohols by using oxygen or air as oxidant in the presence of 9-fluorenone as organic photocatalyst. The presented methodology is applicable to activated alcohols (benzylic or allylic alcohols), but aliphatic, steroidal, and heterocyclic alcohols can also be used as substrates. Mechanistic studies indicate the presence of peroxide and superoxide radicals as the actual oxidants.
关键词： fluorenone,steroids,reactive oxygen species,alcohols,oxidation
更新于2025-09-23 15:21:01
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Flame Propagation Enhancement by Dielectric Barrier Discharge-Generated Intermediate Species
摘要： The interaction between nonthermal plasma (NTP) and fuel-air mixtures was studied both experimentally and by means of simulations, to elucidate their promotional effect on flame propagation. A promotional effect on flame propagation velocity was experimentally observed by generating a dielectric barrier discharge (DBD), prior to spark plug ignition of an n-heptane mixture in a high-pressure and -temperature environment, using a rapid compression and expansion machine (RCEM). A novel method of concentration calibration for mass-spectral analysis was conducted, to determine the intermediate species in the fuel-air mixtures passing through the DBD plasma. The effect of the intermediate chemical species on flame propagation was examined numerically using the PREMIX code, with the observed species being considered as initial additives in the calculations. The promotional effect was reproduced numerically with the addition of alkyl hydroperoxide to an n-heptane/air mixture; and the higher the temperature and leaner the mixture in the parameter region, the more pronounced was the effect. The promotional behavior was examined using reaction path analysis, on the basis of which enhanced low-temperature oxidation reactions, due to the dissociation of the alkyl hydroperoxide, were determined in pre-flame region.
关键词： dielectric barrier discharge,flame propagation velocity,Plasma-assisted combustion,low-temperature oxidation,isomerization
更新于2025-09-23 15:21:01
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Redox Properties of Cu <sub/>2</sub> O(100) and (111) Surfaces
摘要： Intense research efforts are directed towards Cu and Cu2O based catalysts as they are viewed as potential replacements for noble metal catalysts. However, applications are hampered by deactivation, e.g. through facile complete oxidation to CuO. Despite the importance of the redox processes for Cu2O catalysts a molecular level understanding of the deactivation process is still lacking. Here we study the initial stages of oxidization of well-defined Cu2O bulk single crystals of (100) and (111) termination by means of synchrotron radiation X-ray photoemission spectroscopy (XPS) and scanning tunneling microscopy (STM). Exposure of the (100) surface to 1 mbar O2 at 25 ℃ result in formation of a 1.0 monolayers (ML) CuO surface oxide. The surface is covered by 0.7 ML OH groups from trace moisture in the reaction gas. In contrast, neither hydroxylation nor oxidation was observed on the (111) surface under similar mild exposure conditions. On Cu2O(111) the initial formation of CuO requires annealing to ～400 ℃ in 1 mbar O2, highlighting the marked different reactivity of the two Cu2O surfaces. Annealing of the (100) surface, under ultrahigh vacuum conditions, to temperatures up to ～225 ℃ resulted in removal of the OH groups (0.46 ML decrease) at a rate similar to a detected increase in CuO coverage (0.45 ML increase), suggesting the reaction path 2OHadsorbed + Cu2Osolid → H2Ogas + 2CuOsolid. STM was used to correlate the observed changes in surface chemistry with surface morphology, confirming the surface hydroxylation and CuO formation. The STM analysis showed dramatic changes in surface morphology demonstrating a high mobility of the active species under reaction conditions.
关键词： XPS,surface oxidation,redox properties,hydroxylation,STM,Cu2O
更新于2025-09-23 15:21:01
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Design of an inherently-stable water oxidation catalyst
摘要： While molecular water-oxidation catalysts are remarkably rapid, oxidative and hydrolytic processes in water can convert their active transition metals to colloidal metal oxides or hydroxides that, while quite reactive, are insoluble or susceptible to precipitation. In response, we propose using oxidatively-inert ligands to harness the metal oxides themselves. This approach is demonstrated by covalently attaching entirely inorganic oxo-donor ligands (polyoxometalates) to 3-nm hematite cores, giving soluble anionic structures, highly resistant to aggregation, yet thermodynamically stable to oxidation and hydrolysis. Using orthoperiodate (at pH 8), and no added photosensitizers, the hematite-core complex catalyzes visible-light driven water oxidation for seven days (7600 turnovers) with no decrease in activity, far exceeding the documented lifetimes of molecular catalysts under turnover conditions in water. As such, a fundamental limitation of molecular complexes is entirely bypassed by using coordination chemistry to harness a transition-metal oxide as the reactive center of an inherently stable, homogeneous water-oxidation catalyst.
关键词： visible-light driven,hematite,polyoxometalates,water oxidation,catalyst
更新于2025-09-23 15:21:01
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Shape-dependent activity of anisotropic Ag nanostructures supported on TiO2 for the photoelectrocatalytic water oxidation
摘要： Herein, we report shape-dependent photoelectrocatalytic activity of Ag/Ag2O nanostructures supported on pristine or nitrogen-doped TiO2 (NTiO2). Isotropic (spherical) and anisotropic (cubic and triangular) nanocrystals of Ag/Ag2O nanocrystals were fabricated using complexing and surface directing agents. Microscopic images confirmed the formation of nanospheres (～ 50–60 nm), nanocubes (～ 50–70 nm), triangular nanoplates (～ 40–60 nm). The X-ray photoelectron spectroscopy indicated the presence of metallic silver (Ag0) and oxidized silver (Ag+). The as-prepared photoelectrodes were illuminated by Ultraviolet–Visible (λ = 300–600 nm) or visible radiations (λ = > 420 nm), and photoelectrochemical oxidation of water was examined. The findings indicate a significant correlation in the shape of Ag/Ag2O nanostructures, the incident wavelength, and the photoelectrochemical performance. In addition, different performance trend was discerned under Ultraviolet–Visible and visible excitations with respect to the amount of deposited Ag/Ag2O. The variation in activity observed with different shapes of Ag/Ag2O was correlated to enhanced optical property, arising due to the anisotropic structure, and electrical conductivity.
关键词： Photoelectrocatalytic activity,NTiO2,Water oxidation,Shape-dependent,Ag/Ag2O nanostructures,TiO2
更新于2025-09-23 15:21:01