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Enhanced upconversion luminescence in controllable self-assembled BiOBr: Yb3+/Er3+ 3D hierarchical architectures and their application in NIR photocatalysis
摘要： In this work, self-assembled Yb3+/Er3+ co-doped BiOBr 3D flower-like hierarchical architectures (HAs) were synthesized via hydrothermal method. With increasing pH values, the thickness of samples became thinner, and the morphology transforms from 2D nanosheets to self-assembled 3D HAs. Under the excitation of 980 nm, 3D flower-like BiOBr: Yb3+/Er3+ HAs showed a significant enhancement the upconversion (UC) emission, which was about 505 times than that of the 2D nanosheets. The mechanisms for the enhancement of UC emission have been discussed. Moreover, all the samples showed effective photocatalytic activity for the RhB degradation and obviously enhanced performance with increasing pH values under NIR and simulated solar light irradiation, due to the internal electric field effects and efficient utilization of UC emissions. This work gives insight to the guidance of fabricating efficient self-assembled 3D flower-like BiOBr: Yb3+/Er3+ HAs UC materials, which have great potential for the applications in NIR-activated photocatalysts.
关键词： upconversion,BiOBr: Yb3+/Er3+,morphology,NIR-activated photocatalysts
更新于2025-09-11 14:15:04
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Visible-Light Influenced Photocatalytic Activity of Polyaniline -Bismuth Selenide Composites for the Degradation of Methyl Orange, Rhodamine B and Malachite Green dyes
摘要： Polyaniline (PANI) when composited with bismuth selenide nanoflakes (Bi2Se3 NFs), a low bandgap semiconductor, reveals enhanced photocatalytic activity for degradation of organic dyes under irradiation of visible light. The composites synthesized using Bi2Se3NFs templates with different weight percentages of PANI by in-situ chemical oxidative polymerization have been used as efficient photocatalysts for degradation of anionic dye, Methyl Orange (MO), and cationic dyes, Rhodamine B (RhB) and Malachite Green (MG). Based on radical trapping experiments, the mechanism for the photocatalytic degradation of the dyes were proposed taking into account the synergistic effect of PANI with Bi2Se3NFs. The efficient visible-light active photocatalytic property of the polymer-inorganic composites is attributed to composites’ enhanced separation of photogenerated carriers compared to its individual constituents.
关键词： Photocatalysts,PANI,Bi2Se3,Visible light,Dyes,Composites
更新于2025-09-10 09:29:36
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Janus Group-Ⅲ Chalcogenide Monolayers and Derivative Type-Ⅱ Heterojunctions as Water Splitting Photocatalysts with Strong Visible Light Absorbance
摘要： Search for two-dimensional (2D) water splitting photocatalysts is crucial to solve energy crises and environmental problems. In this research, we study the electronic and photocatalytic properties of single-layer Ga2X1X2 (Ga2SeTe, Ga2STe and Ga2SSe) and newly proposed α-Ga2S3/Ga2SSe-A, α-Ga2S3/Ga2SSe-B and α-Ga2S3/Ga2SSe-C van der Walls heterojunctions using first-principles calculations. Theoretical results indicate Ga2X1X2 monolayers present suitable band edges. 2D α-Ga2S3/Ga2SSe-B and α-Ga2S3/Ga2SSe-C belong to type-Ⅱ heterojunctions, and under biaxial strains embody suitable band edges. Comparisons of the valence band maximum (VBM) charge and electric dipole of α-Ga2S3/Ga2SSe-A and α-Ga2S3/Ga2SSe-B demonstrate it is possible to achieve suitable band edges for water splitting by switching electric dipoles. Especially, the three Ga2X1X2 monolayers, α-Ga2S3/Ga2SSe-B and α-Ga2S3/Ga2SSe-C heterojunctions absorb a large amount of visible light, promising they are photocatalysts for water splitting. More importantly, we find the optical absorption coefficients of 2D monolayers and heterojunctions in previous calculations are several times underestimated because the effective volume is not taken into consideration. To obtain reliable absorption coefficients, the real and imaginary parts of dielectric function must be renormalized.
关键词： visible light absorbance,van der Waals heterojunctions,two-dimensional (2D) materials,Janus group-Ⅲ chalcogenide monolayers,water splitting photocatalysts,first-principles calculations
更新于2025-09-10 09:29:36
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Understanding structure-activity relationships in linear polymer photocatalysts for hydrogen evolution
摘要： Conjugated polymers have sparked much interest as photocatalysts for hydrogen production. However, beyond basic considerations such as spectral absorption, the factors that dictate their photocatalytic activity are poorly understood. Here we investigate a series of linear conjugated polymers with external quantum efficiencies for hydrogen production between 0.4 and 11.6%. We monitor the generation of the photoactive species from femtoseconds to seconds after light absorption using transient spectroscopy and correlate their yield with the measured photocatalytic activity. Experiments coupled with modeling suggest that the localization of water around the polymer chain due to the incorporation of sulfone groups into an otherwise hydrophobic backbone is crucial for charge generation. Calculations of solution redox potentials and charge transfer free energies demonstrate that electron transfer from the sacrificial donor becomes thermodynamically favored as a result of the more polar local environment, leading to the production of long-lived electrons in these amphiphilic polymers.
关键词： photocatalysts,transient spectroscopy,hydrogen production,sulfone groups,conjugated polymers
更新于2025-09-10 09:29:36
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Recent development of g-C3N4-based hydrogels as photocatalysts: A minireview
摘要： Solar-driven photocatalysis using graphitic carbon nitride (g-C3N4) is considered the most promising approach for the generation of H2 from water, degradation of organic pollutants, and reduction of CO2. However, bulk g-C3N4 exhibits several drawbacks, such as low specific surface area, high defect density, and fast charge recombination, which result in low photocatalytic performance. Construction of 3D porous hydrogels for g-C3N4 through nanostructural engineering is a rapid, feasible, and cost-effective technique to improve the adsorption capability, stability, and separability of the hydrogel composite; to increase the number of active sites; and to create an internal conductive path for facile charge transfer and high photocatalytic activity. This minireview summarizes the recent progresses in photocatalytic water splitting and dye degradation using g-C3N4-based hydrogels with respect to the state-of-the-art methods of synthesis, preparation, modification, and multicomponent coupling. Furthermore, comprehensive outlooks, future challenges, and concluding remarks regarding using g-C3N4-based hydrogels as highly efficient photocatalysts are presented.
关键词： water splitting,hydrogels,photocatalysts,dye degradation,g-C3N4
更新于2025-09-10 09:29:36
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Effect of carbon nanotubes and carbon nanotubes - gold nanoparticles composite on the photocatalytic activity of TiO <sub/>2</sub> and TiO <sub/>2</sub> -SiO <sub/>2</sub>
摘要： Carbon nanotube (CNT) - gold (Au) nanoparticle (NP) nanocomposite was synthesized by simultaneously reducing the Au ions and depositing Au NPs on the surface of CNT. The functional groups were investigated with FT-IR spectra. From the Raman spectra, D-band and G-band of CNT were identified. As a result, the deposition of nanometer-sized Au NPs on the CNT sites was observed from the transmission electron microscope (TEM) images. The photodegradation of methylene blue (MB) in aqueous solutions was studied using various photocatalysts, including TiO2, TiO2-SiO2, CNT/TiO2, CNT/TiO2-SiO2, Au/TiO2, CNT-Au/TiO2 and CNT-Au/TiO2-SiO2 composites. The CNT addition (2%) leads to a synergic effect, improving the photoactivity of the catalysts. A possible physically-based mechanism was proposed involving the reduction of electron-hole recombination and fast electron-transfer possibility.
关键词： Gold nanoparticle,TiO2-SiO2,TiO2,Carbon nanotube,nano-photocatalysts
更新于2025-09-10 09:29:36
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Fabrication of Gd-La codoped TiO2 composite via a liquid phase plasma method and its application as visible-light photocatalysts
摘要： TiO2 was doped simultaneously with Gd and La using a liquid phase plasma (LPP) reaction to produce a photocatalyst with excellent photoactivity in the visible light region. Gadolinium chloride hexahydrate and lanthanum chloride heptahydrate precursors were used to dope the TiO2 powder with polycrystalline Gd2O3 and La2O3 particles. The doping of TiO2 with rare earth elements using LPP reaction decreased the band gap; the band gap of Gd-La codoped TiO2 photocatalysts (GLTP) was the lowest. The photodegradation efficiency of the TiO2 photocatalysts doped with either Gd or La was superior that of bare TiO2 but the photodegradation efficiency of GLTP was highest in both ultraviolet and visible light sources. Acetaminophen (Acetyl-para-aminophen, APAP) was ultimately decomposed to CO2 and H2O via intermediates, such as p-nitrophenol, hydroquinone and hydroxylhydroquinone, by hydroxyl radicals (HO?) formed on the surface of GLTP.
关键词： Liquid phase plasma,Gd-La codoped TiO2 photocatalysts,Band gap energy,Acetaminophen,Photocatalytic activity
更新于2025-09-10 09:29:36
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Photoelectrocatalytic decolorization of azo dyes with nano-composite oxide layers of ZnO nanorods decorated with Ag nanoparticles.
摘要： Photoelectrocatalysis provides an excellent frame for the application of photocatalytic nanostructured materials on easy recoverable supports. This study reports the two-step synthesis of hierarchically nanostructured ZnO/Ag composite photoelectrodes. Wutzite ZnO was selectively electronucleated as spheroidal seeds on fluor doped tin oxide substrates and nanodecorated with Ag nanoclusters under electrochemical control. Hirearchically organized nanorods were selectively chemically grown on the plane (002) perpendicular to the substrate from ZnO/Ag seeds. Solutions emulating dye effluents with the usual contents of 0.1 M of NaCl and a model azo dye (Methyl Orange) were decolorized using ZnO/Ag nanorods in different treatments. Photocatalysis attained discrete decolorizations of 8% whereas photoelectrocatalysis completely decolorized solutions after 60 min. The influence of the metal/semiconductor interface (ZnO/Ag) as introduced Schottky barrier is studied demonstrating a four-fold enhancement on decolorization kinetics respect bare ZnO nanorods. The influence of the seed growth control on the final photoelectrocatalytic response is reported to control the hierarchical organization of nanorods. This resulted in different decolorization kinetics as result of the differences on the efficient use of the delivered photons conditioned by the photoelectrode structure.
关键词： photocatalysis,photocathode,nano-coating,electrochemical water treatment,Metallic/semiconductor composite photocatalysts
更新于2025-09-10 09:29:36
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Layered lithium niobium (III) oxide—LiNbO <sub/>2</sub> as a visible-light-driven photocatalyst for H <sub/>2</sub> evolution
摘要： The search for visible-light photocatalysts is of great significance in clean energy and environmental applications to best utilize solar radiation. Some layered semiconductor photocatalysts have been found to exhibit promising performance levels. Their superior activity has been linked to the layering within the crystal structure, which may facilitate separation of carriers and, hence the reduction and oxidation reactions. Previous investigations on layered materials focused on oxides containing early transition metal cations with d0 electronic configurations utilizing ultraviolet radiation. Attempts to synthesize layered materials with visible light response have been less successful and the photoactivity of such materials is not very high. Here, we have investigated a layered semiconducting compound, LiNbO2 with nominal d2 electronic configuration (Nb3+). As a result of a sub-valence band originating from filled d orbitals, LiNbO2 exhibits visible light absorption extending to 650 nm and demonstrates interesting photocatalytic activity for hydrogen production.
关键词： clean energy,photocatalysts,layered semi conducting compound,hydrogen production
更新于2025-09-10 09:29:36
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Graphene based nanocomposites for efficient photocatalytic hydrogen evolution: insight into the interface toward separation of photogenerated charges
摘要： Although the reduced graphene oxide (rGO) has been intensively applied to photocatalytic H2 evolution, no enough attention was given to study the interface between photocatalyst and rGO, which is the key point to affect the transportation of photogenerated electron. Herein, in order to research the heterojunctions interface, the series of SrTiO3 photocatalysts with different crystal facets were fabricated to load with rGO for photocatalytic H2 evolution. The characterization measurements and theory calculation verified that the rGO was mainly anchored on the Ti-O bond of SrTiO3. So, compared to {001} facets sample, the {110} facets of SrTiO3, exposed more Ti and O atoms, could form stronger bond with the rGO. Additionally, DFT study deduced that the photoinduced electron could immigrate rapidly from Ti-O bond to the rGO, which was in good agreement with the results of photoelectrochemical and photoluminescence (PL) experiments. Meanwhile, experimentally, the 1 % wt. rGO@SrTiO3 with {110} facets nanocomposite showed the superior photocatalytic H2 yield rate (3.82 mmol/h/g), which was 2.2 times and 3.2 times higher than that of pure SrTiO3 with the same facets and 1 % wt. rGO@SrTiO3 with {001} facets, respectively. Both experiments and theoretical calculations unveiled that the synergetic effect of SrTiO3 facets engineering and rGO loading effectively prompted the immigration of photoinduced electron at the nanocomposites interface. This work provides a rational thinking of a high efficiency rGO-based heterogeneous photocatalysts for solar energy conversion.
关键词： density functional theory study,rGO-based heterogeneous photocatalysts,separation of photogenerated charges,photocatalytic hydrogen evolution,SrTiO3,electron screening effect
更新于2025-09-09 09:28:46