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Perfluorinated porphyrazines
摘要： Nucleophilic substitution of fluorine atoms in the phenyl rings by alkoxy groups was performed in perfluorosubstituted zinc(II) octaphenylporphyrazine [ZnPAF40]. Up to 12 fluorine atoms are substituted in the reaction with sodium butoxide in boiling butanol leading to the formation of [ZnPAF40–n(OBu)n] (n = 6—12). Up to eight monosaccharide groups are introduced in the reaction with 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose (Gal′) in toluene in the presence of sodium hydride leading to the formation of [ZnPaF(40–n)(Gal′)n] (n = 6—8). It was possible to obtain a water-soluble glycoconjugated zinc(II) porphyrazine [ZnPaF(40–n)(Gal)n] after removal of the isopropylidene protecting groups by treatment with trifluoroacetic acid. Substitution products are characterized by electron absorption spectroscopy, NMR spectroscopy, and mass spectrometry. Substituting the fluorine atoms with monosaccharide residues leads to an increase in the fluorescence quantum yield from ФF = 0.19 for [ZnPAF40] to 0.29 for [ZnPA(Gal′)nF40–n] (n = 6—8).
关键词： galactose,perfluorinated porphyrazines,water soluble porphyrazines,nucleophilic aromatic substitution
更新于2025-11-19 16:46:39
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Influence of water-controlled release process on the physical and chemical property of nanosize TiO <sub/>2</sub> particles
摘要： The water-controlled release process (WCRP) was utilized for the synthesis of TiO2 photocatalyst. The effect of alkylated esterified WCRP system on the morphology, specific surface area (SSA) and photocatalytic activity of TiO2 were studied systematically. By changing the structure of alcohol and acid involved in the esterification reaction, we found that the SSA and photocatalytic activity of TiO2 obtained in an ethanol/acetic acid reaction mixture showed the best results. Interestingly, the TiO2 obtained in t-butanol/acetic acid contains both the anatase and rutile phase, while the other systems only possessed anatase phases. The conditions of ethanol and acetic acid esterification were optimized and the experimental results showed that the SSA of nano-TiO2 was improved by shorting the reaction time or adding an organic solvent, which can form an azeotrope with water, but no effect on the photocatalytic activity could be observed. The reaction mechanism of esterified WCRP system was furthermore studied by NMR spectroscopy, showing three kinds of reaction, namely esterification, etherification and hydrolysis.
关键词： water-controlled release process(WCRP),p-toluenesulfonic acid,esterification,photocatalytic,titania
更新于2025-11-14 17:04:02
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Co and Fe Codoped WO <sub/>2.72</sub> as Alkaline‐Solution‐Available Oxygen Evolution Reaction Catalyst to Construct Photovoltaic Water Splitting System with Solar‐To‐Hydrogen Efficiency of 16.9%
摘要： Oxygen evolution electrode is a crucial component of efficient photovoltaic-water electrolysis systems. Previous work focuses mainly on the effect of electronic structure modulation on the oxygen evolution reaction (OER) performance of 3d-transition-metal-based electrocatalyst. However, high-atomic-number W-based compound with complex electronic structure for versatile modulation is seldom explored because of its instability in OER-favorable alkaline solution. Here, codoping induced electronic structure modulation generates a beneficial effect of transforming the alkaline-labile WO2.72 (WO) in to efficient alkaline-solution-stable Co and Fe codoped WO2.72 (Co&Fe-WO) with porous urchin-like structure. The codoping lowers the chemical valence of W to ensure the durability of W-based catalyst, improves the electron-withdrawing capability of W and O to stabilize the Co and Fe in OER-favorable high valence state, and enriches the surface hydroxyls, which act as reactive sites. The Co&Fe-WO shows ultralow overpotential (226 mV, J = 10 mA cm?2), low Tafel slope (33.7 mV dec?1), and good conductivity. This catalyst is finally applied to a photovoltaic-water splitting system to stably produce hydrogen for 50 h at a high solar-to-hydrogen efficiency of 16.9%. This work highlights the impressive effect of electronic structure modulation on W-based catalyst, and may inspire the modification of potential but unstable catalyst for solar energy conversion.
关键词： electrocatalysis,photovoltaic water splitting,oxygen evolution reaction,codoping,WO2.72
更新于2025-11-14 17:04:02
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Ups and Downs of Water Photodecolorization by Nanocomposite Polymer Nanofibers
摘要： Given the exponentially expanding water pollution causing water scarcity, there is an urgent need for operative nanotechnological systems that can purify water, with insignificant energy consumption, and rapidly. Here, we introduce a nanocomposite system based on TiO2 nanoparticles (NPs) and PES nanofibers (NFs) that can adsorb and then photodecompose organic water pollutants such as dye molecules. We evaluate pros and cons of this system with respect to its purification efficiency and structural properties that can be impacted by the photocatalytic activity of the nanofillers. While the material is superhydrophilic and able to remove 95% methylene blue (MB) from water via adsorption/photodecomposition, its thermomechanical properties decline upon UV irradiation. However, these properties still remain at the level of the neat NFs. The removal behavior is modeled by the first- and second-order kinetic models from the kinetic point of view. The nanocomposite NFs’ removal behavior complies much better with the second-order kinetic model. Overall, such feedbacks implied that the nanocomposite can be effectively applied for water treatment and the structural properties are still as reliable as those of the neat counterpart.
关键词： nanofiber,photodegradation,dye removal,water treatment,photocatalysis
更新于2025-11-14 17:03:37
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S, N co-doped graphene quantum dots-induced ascorbic acid fluorescent sensor: Design, characterization and performance
摘要： In this work, new detection route for ascorbic acid was designed. First, highly luminescent sulfur and nitrogen doped graphene quantum dots (S,N-GQDs) were prepared via simple hydrothermal method using citric acid and thiourea as the C, N and S sources respectively. The prepared S,N-GQDs are characterized by XRD, HRTEM, FTIR, EDS and PL. Investigations showed that prepared S,N-GQDs have a good photostability and excitation-dependent emission fluorescence. Prepared S,N-GQDs showed maximum excitation wavelength and emission wavelength at 400 and 462nm, respectively. In the following, prepared S,N-GQDs were applied as a photoluminescence probe for detection of ascorbic acid (AA). The designed sensor was based on “off-on” detection mode. The developed sensor had a linear response to AA over a concentration range of 10-500μM with a detection limit of 1.2μM. The regression equation is Y = 0.0014 X+1.2036, where Y and X denote the fluorescence peak intensity and AA concentration, respectively.
关键词： Graphene quantum dots,Quantum confinement,Fluorescence sensor,Nanostructures,Water-soluble vitamin,Quenching
更新于2025-11-14 15:32:45
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Dynamically Optimized Multi-Interface Novel BiSI-Promoted Redox Sites Spatially Separated N-p-n Double Heterojunctions BiSI/MoS2/CdS for Hydrogen Evolution
摘要： Novel BiSI promoted n-p-n double heterojunctions multi-interface photocatalyst BiSI/MoS2/CdS was constructed. BiSI is applied to photocatalytic hydrogen evolution. It possesses a small band gap and a strong optical absorption coefficient, therefore, the optical absorption scope and coefficient of MoS2/CdS have been effectively enhanced by compounding with BiSI. The continuous heterojunctions strengthened the function of single junction and guided the carriers’ transfer direction, thus the redox reactions occur at spatially separated sites. Built-in electric field along the radial direction of BiSI nanorod and MoS2 interlayer helps to transport carriers within lifetime. Carrier dynamics is optimized by multi-interface structure. In general, a new material BiSI is introduced to construct a multi-interface structure to optimize carrier dynamics, which resulted in a 46-fold increase in hydrogen production efficiency.
关键词： multi-interface,dynamics optimization,enhanced optical absorption,photocatalytic water splitting,n-p-n continuous heterojunctions,BiSI
更新于2025-11-14 15:29:11
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Rapid preparation of homogeneous carbon dots with yellow fluorescence and formation mechanistic investigation
摘要： In this study, homogeneous carbon dots with yellow fluorescence and high absolute fluorescence quantum yields (78.6%) were firstly prepared through a one-step solvothermal method without complicated process of separation, in which sodium citrate, carbamide, and anhydrous calcium chloride were adopted as precursors, while toluene was selected as solvent. The as-prepared carbon dots with an average size of 5.9 nm have a high degree of crystallinity. According to the discussion of the formation mechanism carbon dots, it is found that the toluene guarantee the formation of crystalline core and Ca2+ promotes the formation of carbonaceous core with high crystallinity, which is responsible for the ultrahigh quantum yield. Furthermore, the fluorescent properties of carbon dots are excellent in organic solvents and could be quenched by water, making them a promising material used without any modification in the detection of water in organic solvents, which has a great influence on organic chemical reaction, and may even determine the resultant, yield, and selectivity of organic reaction.
关键词： Detection of water content,Ultrahigh quantum yield,Yellow fluorescence,Carbon dots,Quantum dot
更新于2025-11-14 15:28:36
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Direct Observation of Structural Evolution of Metal Chalcogenide in Electrocatalytic Water Oxidation
摘要： As one of the most remarkable oxygen evolution reaction (OER) electrocatalysts, metal chalcogenides have been intensively reported due to their high OER activities during the past few decades. It has been reported that electron-chemical conversion of metal chalcogenides into oxides/hydroxides would take place after OER. However, the transition mechanism of such unstable structures, as well as the real active sites and catalytic activity during OER for these electrocatalysts, has not been understood yet, which urgently needs a direct observation for the electrocatalytic water oxidation process, especially at nano or even angstrom scale. In this research, by employing advanced Cs-corrected transmission electron microscopy (TEM), a step by step oxidational evolution of amorphous electrocatalyst CoSx into crystallized CoOOH in OER has been in situ captured: irreversible conversion of CoSx to crystallized CoOOH is initiated on the surface of electrocatalysts with a morphology change via Co(OH)2 intermediate during OER measurement, where CoOOH is confirmed as the real active species. Besides, this transition process has also been confirmed by multiple applications of X-ray photoelectron spectroscopy (XPS), in situ Fourier-transform infrared spectroscopy (FTIR) and other ex situ technologies. Moreover, based on this discovery, a high-efficiency electrocatalyst of a nitrogen-doped graphene foam (NGF) coated by CoSx has been explored through a thorough structure transformation of CoOOH. We believe this in situ and in-depth observation of structural evolution in OER measurement can provide insights into the fundamental understanding of the mechanism for OER catalysts, thus enabling the more rational design of low-cost and high-efficient electrocatalysts for water splitting.
关键词： structural evolution,XPS,in situ TEM,water oxidation,cobalt chalcogenide
更新于2025-11-14 15:27:09
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Photoelectrochemical enhancement from deposition of BiVO4 photosensitizer on different thickness layer TiO2 photoanode for water splitting application
摘要： TiO2 is a prominent photocatalyst and has been pioneering the research in water splitting for hydrogen cell production. However, TiO2 has low visible region absorption which limit its functionality as a photoabsorber and requires addition of other high absorptive material such as BiVO4. Fabrication of TiO2 photoanode on FTO substrate and deposition of BiVO4 on TiO2 were done using simple spin coating procedure. TiO2/BiVO4 photoelectrode were first tested for its photo absorption, photocurrent generation and electrical impedance to obtain the optimized sample. Optimized sample then further tested for its photocurrent generation stability using linear sweep voltammetry and time dependent photocurrent test. Photo absorption enhancement from TiO2/BiVO4 of almost 10 folds achieved along the visible region comparing to pure TiO2. Photogenerated charge produced from TiO2/BiVO4 is also 3 folds higher compared to pure TiO2at water oxidation threshold potential at 1.23 V vs. RHE. From photocurrent generation analysis, heterostructure of TiO2/BiVO4 proven to produce more than 3 folds higher photocurrent comparing to both pure TiO2 and BiVO4.
关键词： Z-scheme,Bismuth vanadate,Thin-film,Titanium dioxide,Photoelectrochemical water splitting
更新于2025-11-14 15:19:41
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Synthesis of novel Mn-doped Fe2O3 nanocube supported g-C3N4 photocatalyst for overall visible-light driven water splitting
摘要： A novel Mn-doped Fe2O3 modified g-C3N4 nanosheets composite has been prepared for overall water splitting. Structure characterizations reveal that the Mn are successfully doped in the Fe2O3 nanoparticle and a close interface between g-C3N4 and Mn-doped Fe2O3is obtained. The optimized FMC-10 photocatalyst has a H2 evolution of 51 μmol h?1. The improved photocatalytic performance can be ascribed to the synergy effect of both Mn-doped Fe2O3and g-C3N4. Doping Fe2O3 with Mn promotes photo-induced charges and increases the charge transfer for the improved conductivity of the bulk Fe2O3, while favorable contacting with g-C3N4 enhances the charge separation ability.
关键词： Mn doped,Pure water splitting,g-C3N4,Fe2O3
更新于2025-11-14 15:15:56