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Post-annealed graphite carbon nitride nanoplates obtained by sugar-assisted exfoliation with improved visible-light photocatalytic performance
摘要： Two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanoplates (CNNP) have become a hot research topic in photocatalysis due to their small thickness and large specific surface area that favors charge transport and catalytic surface reactions. However, the wide application of 2D g-C3N4 nanoplates prepared by ordinary methods suffers from increased band gaps with a poor solar harvesting capability caused by the strong quantum confinement effect and reduced conjugation distance. In this paper, a facile approach of exfoliation and the following fast thermal treatment of the bulk g-C3N4 is proposed to obtain a porous few-layered g-C3N4 with nitrogen defects. Due to the preferable crystal, textural, optical and electronic structures, the as-obtained porous CNNP demonstrated a significantly improved photocatalytic activity towards water splitting than the bulk g-C3N4 and even the 3 nm-thick CNNP obtained by sugar-assisted exfoliation of the bulk g-C3N4. The difference in the enhancement factors between the H2O splitting and organic decomposition has revealed the effect of N defects. This study offers insightful outlooks on the scalable fabrication of a porous few-layered structure with a promoted photocatalytic performance.
关键词： Photocatalytic activity,g-C3N4 nanoplates,Co-grinding,Thermal treatment,Sugar
更新于2025-09-23 15:19:57
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TiO2 nanowire photocatalyst for dual-ion production in laser desorption/ionization (LDI) mass spectrometry
摘要： It has been challenging to detect small analytes in both positive and negative ion modes using organic matrices in conventional matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Herein, TiO2 nanowires are presented as a solid matrix to form dual-ion of analytes regardless of chemical properties and to demonstrate the versatile applicability in LDI-MS.
关键词： LDI-MS,TiO2 nanowires,photocatalytic activity,dual-ion production,small analytes detection
更新于2025-09-23 15:19:57
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Immobilization of C/Ce-codoped ZnO nanoparticles on multi-walled carbon nanotubes for enhancing their photocatalytic activity
摘要： C/Ce-codoped ZnO nanoparticles immobilized onto multi-walled carbon nanotubes (C/Ce-ZnO@MWCNT) were successfully fabricated via the hydrothermal method for degradation of methylene blue (MB) under visible light irradiation. The prepared C/Ce-ZnO@MWCNT samples were characterized by XRD, XPS, FTIR, FE-SEM, EDX, BET, and diffuse reflectance spectroscopy. The obtained results indicated that the photocatalytic activity of all the MWCNTs-containing samples was higher than those of the bare ZnO and C/Ce-codoped ZnO nanoparticles. Besides, the C/Ce-ZnO@MWCNT composite with 50 wt% MWCNT showed the highest photocatalytic activity with the MB removal efficiency of 96.5% recorded within 90 min under visible light illumination using 1.0 g/L catalyst dosage at pH of 9 and MB concentration of 30 ppm. The degradation mechanism controlled by the charge transfer process in C/Ce-ZnO@MWCNT composite was proposed and discussed in detail. In addition, the long-term-use ability of the photocatalyst was also evaluated through experiments conducted in continuous cycles.
关键词： visible light,C/Ce-ZnO@MWCNT,photocatalytic activity,multi-walled carbon nanotube,methylene blue
更新于2025-09-23 15:19:57
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One-pot biosynthesis of SnO2 quantum dots mediated by Clitoria ternatea flower extract for photocatalytic degradation of rhodamine B
摘要： In this study, SnO2 quantum dots (QDs) have been successfully biosynthesized using Aparajitha (Clitoria ternatea) flower extract as the green reducing agent and then used as effective photocatalysts for the degradation of rhodamine B (RhB) under UV light irradiation. Clitoria ternatea flower extract contains flavanols and flavonoids, which can serve as reducing agents to convert Sn2+ precursors into Sn° NPs, which are then oxidized to 4–10 nm SnO2 QDs at 400 °C for 2 h. A blue shift in the adsorption wavelength of biosynthesized SnO2 QDs (3.66 eV) in comparison with bulk SnO2 (3.54 eV) is obtained, which can reduce the electron–hole recombination rate of SnO2. In addition, the specific surface area of SnO2 QDs is almost two times higher than that of bulk SnO2, resulting in the acceleration of photocatalytic degradation efficiency and rate of RhB under UVB light irradiation. The photodegradation performance of RhB over SnO2 QDs is highly dependent on several parameters, including H2O2 concentration, catalyst dosage, and pH. The liquid chromatography-mass spectrometric spectra and radical scavenger experiments indicate that the hydroxyl radicals play a crucial role in photodegradation, which can undergo N-deethylation and ring cleavage reactions to produce intermediates of N, N-diethyl-N’-ethylrhodamines, dihydroxybenzoic acid, and maleic acid. Moreover, a possible reaction mechanism for RhB photodegradation over SnO2 QDs is proposed. Results obtained in this study clearly indicate that the extract is an effective bioreagent to develop the green chemistry for the one-pot synthesis of SnO2 QDs photocatalysts for the degradation of pollutants in aqueous solutions.
关键词： Rhodamine B (RhB),Clitoria ternatea flower extract,SnO2 quantum dots,Photocatalytic activity
更新于2025-09-23 15:19:57
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Synthesis of 3D CQDs/urchin-like and yolk-shell TiO2 hierarchical structure with enhanced photocatalytic properties
摘要： A novel CQDs/TiO2 hierarchical structure with enhanced photocatalytic properties was achieved by uniformly decorating urchin-like and yolk-shell TiO2 microspheres (UYTMs) with carbon quantum dots (CQDs) through an environmentally friendly hydrothermal process. The CQDs were ?rstly synthesized by the electrochemical method, and the TEM, Raman and PL characterizations strongly indicated that the as-prepared CQDs exhibited good dispersion, high crystallinity and unique up-conversion properties. The UYTMs synthesized by a NaOH-assisted hydrothermal process showed stable 3D hierarchical structure and large surface area, which was bene?cial for light absorption and contacting with contamination. The good combination of CQDs and UYTMs was further successfully achieved during the hydrothermal process, and demonstrated by a series of tests. The photocatalytic experiments suggested that the CQDs/UYTMs exhibited better photocatalytic activities than the pure UYTMs and P25 under both visible and UV light irradiation. The CQDs/UYTMs combining with 6 wt% of CQDs showed the best photocatalytic e?ciency, while excessive CQDs tended to inhibit the photocatalytic activity. According to the results and discussions, a possible mechanism in improving the photocatalytic e?ciency of the CQDs/UYTMs is signi?cantly proposed. The up-conversion property of CQDs can broaden the absorption spectrum of CQDs/UYTMs to the visible light. Moreover, the CQDs, as the electron reservoirs, are e?cient to separate the electrons and holes, leading to an improved photocatalytic activity of CQDs/UYTMs.
关键词： Carbon quantum dots,Urchin-like microspheres,Photocatalytic activity,TiO2,Yolk shell
更新于2025-09-23 15:19:57
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Controllable synthesis of transition metal ion-doped CeO2 micro/nanostructures for improving photocatalytic performance
摘要： Ceria (CeO2) micro/nanostructures with various sizes and shapes were successfully synthesized by doping with a series of transition metal ions without any surfactant or template. The crystal structure, morphology, and photocatalytic performance of CeO2 and Co-, Zr-, Cu-doped CeO2 were characterized. The lattice parameters, which indicate the crystal structure distortion and change of Ce4+, were changed by incorporating a transition metal into the CeO2. Doping with transition metal ion could broaden the absorption range from ultraviolet to visible region and enhance the concentration of oxygen vacancies, which exhibited a significantly lower optical band than pure CeO2. The photocatalytic studies revealed that CeO2 with a spate of oxygen vacancies displayed a higher photocatalytic activity than pure CeO2 in degrading the organic pollutant rhodamine B (RhB). Furthermore, the O2? and ?OH radicals formed during photocatalysis process were revealed by means of nitrotetrazolium blue chloride (NBT) reduction method and a terephthalic acid (TA) fluorescence probe method, respectively, which discovers that radicals were crucial for the degradation of RhB. The H2-TPR confirmed that a small amount of transition metal ions significantly affected the oxidation state of the surface cations and oxygen vacancies. This study clearly reveals the effects of different transition metal ion dopants on the morphologies and photocatalytic performance of transition metal ion-doped CeO2 micro/nanostructures.
关键词： oxygen vacancy,CeO2,metal ion-doping,morphology,photocatalytic activity
更新于2025-09-23 15:19:57
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SiO2-stabilized Bi nanoparticles: a high active and stable visible light photocatalyst
摘要： A SiO2-coated Bi nanoparticle structure in 40?60 nm with high activity and stability was designed by a liquid phase chemical reduction method. The effect of SiO2 layer on high active Bi nanoparticles was studied by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and thermo-gravimetric and differential thermal analysis characterizations. The SiO2 layer effectively enhanced the stability of Bi core without having negative effect on its activity. The as-prepared Bi@SiO2 nanoparticles showed high activity and recycling stability both in photocatalytic degradation of pollutant (rhodamine B and bisphenol A, respectively) and hydrogen exhalation reaction (HER). The photocatalytic degradation mechanism of Bi@SiO2 nanoparticles under visible light irradiation was discussed. The porous structure of SiO2 layer performed transport channel for electrons and active species, and enhanced the plasmonic photocatalytic effect of Bi.
关键词： HER.,stabilization,photocatalytic activity,Bi@SiO2 nanoparticles
更新于2025-09-19 17:15:36
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Functionalization of cotton fabric with bismuth oxyiodide nanosheets: applications for photodegrading organic pollutants, UV shielding and self-cleaning
摘要： A multifunctional cotton fabric was prepared by immobilizing bismuth oxyiodide (BiOI) nanosheets on the surface of cotton treated to briefly dissolve surface molecules with upon the low-temperature addition of NaOH and urea (cotton micro-dissolution). Immobilization was accomplished by successive adsorption and reaction (SILAR) at the temperature (* 25 °C). The morphology, structural characteristics, photodegradation ability for organic pollutants, UV shielding, and self-cleaning of the treated fabric were studied. The growth rate and uniformity of the BiOI nanosheets were compared between the treated fabrics and the untreated fabrics. The absorption wavelength of the cotton fabric with BiOI nanosheets was extended to the visible light (* 630 nm) region. Under visible light irradiation, cotton fabric containing BiOI nanosheets (BiOI > 8.4 wt%) showed remarkable photocatalytic ability for degrading rhodamine B (RhB) with a degradation rate of 99% (C0 = 20 mg/L) and 95% after the first and sixth cycle, respectively. The ultraviolet protection factor (UPF) of cotton fabric with BiOI nanosheets was > 50, and its transmittance of ultraviolet A (T(UVA)) was < 5%. The cotton fabric with BiOI nanosheets also exhibited superhydrophobic and self-cleaning properties. Thus, the cotton fabric with BiOI nanosheets has great potential for application as a multifunctional protective material.
关键词： BiOI nanosheets,Visible-light photocatalytic activity,Superhydrophobicity,Ultraviolet protection factor
更新于2025-09-19 17:15:36
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Efficient Visible-Light-Induced Photocatalytic Activity of SrTiO <sub/>3</sub> Co-Doped With Os and N: A GGA?+? <i>U</i> Investigation
摘要： A systematic investigation based on spin-polarized DFT + U has been carried out to study the electronic structure of charge compensated (Os, 2N)-codoped SrTiO3 as compared with that of pure SrTiO3, Os-doped SrTiO3, N-doped SrTiO3, and charge non-compensated (Os, N)-codoped SrTiO3. The calculated band gap of pure SrTiO3 is improved to 3.22 eV using GGA + U method by choosing appropriate U values, which is in good agreement with the experimental value (3.25 eV). Although charge non-compensated co-doping with (Os, N) significantly reduces the photoabsorption energy by introducing localized in-gap impurity states of Os-5d, N-2p, and O-2p, unfortunately, the presence of these states may hinder charge carrier mobility. The calculated results show that the charge compensated co-doping with one Os and two N leads to the complete passivation of the mid gap Os-5d and O-2p impurity states, thus the positions of the band edges are extended to satisfy the criteria for overall water splitting under visible-light. The present predictions demonstrate that the charge compensated (Os, 2N)-codoped SrTiO3 can be a desirable effective photocatalyst for highly active visible-light-induced hydrogen production from water splitting due to the enhanced visible-light activity as well as decreased electron–hole recombination rate.
关键词： photocatalytic activity,doping,first-principles calculations,SrTiO3
更新于2025-09-19 17:15:36
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One dimensional hierarchical BiOCl microrods: their synthesis and their photocatalytic performance
摘要： In this work, one dimensional hierarchical BiOCl microrods were controllably synthesized via a hydrothermal method using sodium citrate as the structure-directing agent. Each hierarchical BiOCl structure is made up of many BiOCl nanosheets in which the size and thickness are controlled by the concentration of sodium citrate. The high-resolution transmission electron microscopy (HRTEM) measurements show that each nanosheet consists of the BiOCl hierarchical structure with exposed (001) (top surface) and (110) (side surface) facets. With the amount of sodium citrate increasing, the ratio (110)/(001) gradually increases. These hierarchical BiOCl architectures exhibit a more outstanding photocatalytic activity than BiOCl nanosheets with exposed (001) facets, and rhodamine B (RhB) and methyl orange (MO) can be degraded in 3 and 4 min, respectively. This enhanced photocatalytic performance is ascribed to the fast separation and transfer of photogenerated electron–hole pairs, the formation of hierarchical architectures and the large BET surface areas. Radical scavenger experiments indicate that holes (h+) and superoxide radicals (˙O2?) are the main active species for MO degradation during the photocatalytic process.
关键词： BiOCl,hydrothermal synthesis,photocatalytic activity,hierarchical structure,sodium citrate
更新于2025-09-19 17:15:36