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Visible-Light Photocatalyzed Deoxygenation of N-Heterocyclic <i>N</i> -Oxides
摘要： A scalable and operationally simple method is described that allows for the chemoselective deoxygenation of a wide range of N-heterocyclic N-oxides (a total of 36 examples). This visible-light-induced protocol features the use of only commercially available reagents, room-temperature conditions, and unprecedented chemoselective removal of the oxygen atom in a quinoline N-oxide in the presence of a pyridine N-oxide in the same molecule through the judicious selection of a photocatalyst.
关键词： chemoselective,deoxygenation,room-temperature,N-heterocyclic N-oxides,visible-light photocatalysis
更新于2025-09-09 09:28:46
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Shape Tailored TiO <sub/>2</sub> Nanostructures and Their Hybrids for Advanced Energy and Environmental Applications: A Review
摘要： Shape tailored TiO2 nanostructures with various dimensionality (zero to three dimension) have unique physicochemical and functional properties that facilitates its efficient energy and environment applications, e.g., solar light driven photocatalytic hydrogen generation and decontamination of organic/inorganic toxic pollutants, CO2 reduction into the hydrocarbon fuels, solar cells, supercapacitors and lithium-ion batteries etc. However, the wide band gap nature and the fast recombination of the photogenerated charge carriers in TiO2 usually limit its overall performance under solar light illumination. In this review, we present a state of the art on the fabrication techniques of shape tailored TiO2 nanostructures and the strategies employed to make the system catalytically more efficient. Though shape tailored TiO2 nanostructures with large specific surface area and highly energetic (001) facet exposed TiO2 nanostructures (2D and 3D) can enhance the photocatalytic efficiency to a reasonable extent, further surface engineering is needed for the modification of the electronic band arrangement, visible light sensitization and efficient charge separation. Herein, TiO2 heterostructures (HSs) with metal/non-metal doping, surface fluorination, plasmonic noble metal nanoparticles (NPs) and coupling with the narrow band gap suitable semiconductor (type-II) are discussed in details covering from zero dimensional to three dimensional heterostructures. The synthesis strategies, charge transfer mechanism and their participation in the photocatalysis are elaborated. Though one dimensional TiO2 HSs have been widely studied, we present the recent development of critical surface engineering strategies of two and three dimensional systems, which give rise to the excellent properties including the enlargement of surface area, light absorption capability and efficient separation of electrons/holes resulting in the superior performance in advanced applications. Based on recent breakthroughs in the field, future directions and outlook of the field are presented at the end.
关键词： Type-II Heterostructure,2D TiO2,3D TiO2,Shape Tailored TiO2 Nanostructures,1D TiO2,Visible Light Photocatalysis,Hydrogen Production,0D TiO2,Plasmonic Heterostructure
更新于2025-09-09 09:28:46
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Novel photocatalyst nitrogen-doped simonkolleite Zn5(OH)8Cl2·H2O with vis-up-conversion photoluminescence and effective visible-light photocatalysis
摘要： As photocatalysts exhibit selectivity toward various pollutants, it is necessary to develop different and novel photocatalysts. In this work, a novel photocatalyst-nitrogen-doped simonkolleite Zn5(OH)8Cl2·H2O (DSM) is prepared through a new facile method: calcinating the mixture of zinc hydroxide, urea, and guanidine hydrochloride at 575?°C for 1?h in a furnace with an air atmosphere. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra, UV–visble near-infrared diffuse reflection spectra (UV–Vis–NIR DRS), Brunauer–Emmett–Teller (BET) method, Ramen spectra and Zeta potential measurement, photocatalytic properties, as well as active species trapping experiments. XRD and XPS show the as-prepared powder is nitrogen-doped simonkolleite Zn5(OH)8Cl2H2O (DSM) with a small ZnCl2 fraction. SEM investigation indicates that the as-prepared powder possesses a flower-like layered shape. The UV–Vis–NIR exhibits that after doping, the DSM possesses strong light absorption in the ranges of 300–500 and 1400–2500?nm, a direct electronic transition with a band gap energy of 2.469?eV. PL measurement reveals a strong photoluminescence and an up-conversion from lower to higher-energy visible light in as-prepared samples. Zeta potential investigations show that during photocatalysis, the charges on as-prepared photocatalyst are positive. The photocatalytic experiments show a good dark adsorption, a high photodegradation (99.4% at 60?min), a high pseudo-first-order constant (k) of 0.0261?min?1. Meanwhile, the active species trapping experiments suggest that hole (h+) is the dominant active species during photocatalysis. It is concluded that the doping favors in enhancing vis-light-photocatalysis. This work makes a significant contribution to the literature.
关键词： photocatalyst,nitrogen-doped simonkolleite,visible-light photocatalysis,photoluminescence
更新于2025-09-09 09:28:46
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mpg-C <sub/>3</sub> N <sub/>4</sub> /Ag <sub/>2</sub> O Nanocomposites Photocatalysts with Enhanced Visible-Light Photocatalytic Performance
摘要： To study the photocatalytic activity under visible light irradiation, a series of mesoporous graphitic carbon nitride (mpg-C3N4)/Ag2O photocatalysts were synthesized. The as-prepared photocatalysts were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption Brunauer-Emmett-Teller method (N2-BET), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectra (DRS), and photoluminescence spectra (PL) methods to determine their phase structure, purity, morphology, spectroscopic and photoluminescence emission performance, respectively. Photocatalytic degradation of methyl orange (MO) aqueous solution under visible-light irradiation indicated that the mpg-C3N4/Ag2O-50 nanocomposite exhibited the best activity. The degradation rate of MO reached to 90.8% in 120 min onto the mpg-C3N4/Ag2O-50 nanocomposite, and as compared with the pure mpg-C3N4 and Ag2O samples, the photocatalytic activity of the mpg-C3N4/Ag2O-50 nanocomposite was greatly enhanced. The enhancement of photocatalytic activity was mainly ascribed to the enhanced visible-light absorption ability and the formation of p–n heterojunctions between counterparts of the nanocomposites, which promoted the generation and separation of charge carriers.
关键词： mpg-C3N4/Ag2O,MO Degradation,Photocatalytic Activity,Visible-Light Photocatalysis,p–n Heterojunctions
更新于2025-09-04 15:30:14
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Fabrication of highly efficient and hierarchical CdS QDs/CQDs/H-TiO2 ternary heterojunction: Surpassable photocatalysis under sun-like illumination
摘要： Highly efficient and durable visible-light utilized nanocomposites have a vital role in environmental pollutants remediation. Hence, in this study, we have fabricated CdS QDs co-sensitized CQDs/H-TiO2 (Hollow Titania) ternary heterostructures (CdS QDs/CQDs/H-TiO2) in a facile region-selective deposition route. The as-fabricated nanocomposites were evidently characterized by physicochemical techniques. CdS QDs were uniformly distributed on the smooth surface of hierarchical CQDs/H-TiO2 heterojunction. The as-fabricated CdS QDs/CQDs/H-TiO2 nanocomposite has high-performances for efficient degradation efficacy of phenol, MB and RhB which exhibited enhanced degradation activities with rate constants (k) of 0.03, 0.051 and 0.045 min-1, respectively. All these superior photocatalytic activities obviously attributed to the effect of calcination temperature, enhanced photocurrent, minimized recombination of photo-induced charges in the photocatalysis and optimum content of CdS QDs have the distinct basis for the close interfacial connection developing. In addition, evidenced on the arguable results of electron spin resonance and radical-trapping experiments, the primary reactive-oxygen species and a plausible reaction-mechanism for organic pollutants degradation over CdS QDs/CQDs/H-TiO2 were proposed. This creative work is strategically considered an important step to potentially enhance the utilization of TiO2 in various fields as visible light-induced heterojunction.
关键词： Hollow TiO2,CdS QDs/CQDs/H-TiO2,Visible-light photocatalysis,CQDs/H-TiO2,Environmental remediation
更新于2025-09-04 15:30:14
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Fabrication of Perylene Tetracarboxylic Diimide-Graphitic Carbon Nitride Heterojunction Photocatalyst for Efficient Degradation of Aqueous Organic Pollutants
摘要： Metal-free g-C3N4 is the promising candidate for the next generation visible light-responsive photocatalyst, however, high recombination probability of the photogenerated charge carriers on g-C3N4 limits its photocatalytic activity. To further increase the intrinsic photocatalytic activity of g-C3N4, here perylene tetracarboxylic diimide-g-C3N4 heterojunctions (PDI/GCN) are prepared by one-step imidization reaction between perylene tetracarboxylic dianhydride (PTCDA) and g-C3N4 in aqueous solution. By the combination of various testing results it is confirmed that the surface hybridization of PTCDA and g-C3N4 in the PDI/GCN heterojunctions via O=C?N?C=O covalent bonds occurs at lower PTCDA-to-g-C3N4 weight percentage. By selecting p-nitrophenol and levofloxacin as the target organic pollutants, the visible light photocatalytic performance of the PDI/GCN heterojunctions are studied. It shows that the PDI/GCN heterojunction prepared at PTCDA-to-g-C3N4 weight percentage of 1% exhibits remarkably higher visible light photocatalytic degradation and mineralization ability towards aqueous target pollutants as compared with g-C3N4 and Degussa P25 TiO2. On the basis of the experimental results including photoelectrochemistry, indirect chemical probe and electron spin resonance spectroscopy it is verified that the surface hybridization in the heterojunctions is responsible for this enhanced photocatalytic activity via accelerating the migration and separation of the photogenerated charge carriers, causing to produce more active species like ?O2?, hVB+ and ?OH for deep oxidation of PNP or LEV to CO2 and inorganic anions.
关键词： graphitic carbon nitride,heterojunction,perylene tetracarboxylic diimide,visible light photocatalysis,organic pollutant
更新于2025-09-04 15:30:14
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Semiconductor Heterojunctions for Enhanced Visible Light Photocatalytic H2 Production
摘要： Semiconductor-based heterojunctions have been shown to be effective photocatalytic materials to overcome the drawbacks of low photocatalytic efficiency that results from a high rate of electron?hole recombination and narrow photo-response range. In this paper, we report on the study of heterojunctions made from visible light active, graphitic carbon nitride, g-C3N4), and UV light active, strontium pyroniobate, Sr2Nb2O7. Heterojunctions made from a combination of g-C3N4 and nitrogen-doped Sr2Nb2O7 obtained at different temperatures were also studied to determine the effect of N doping. The photocatalytic performance was evaluated by using photocatalytic hydrogen evolution reaction (HER)from water g under visible light irradiation. It was found that the photocatalytic activities of as prepared heterojunctions are significantly higher than that of individual components under similar conditions. Heterojunction formed from g-C3N4 and N-doped Sr2Nb2O7 at 700oC (CN/SNON-700) showed better performance than heterojunction made from g-C3N4 and Sr2Nb2O7 (CN/SNO). A plausible mechanism for the heterojunction enhanced photocatalytic activity is proposed based on, relative band positions, and photoluminescence data.
关键词： graphitic carbon nitride,visible light photocatalysis,strontium pyroniobate,Semiconductor heterojunctions,hydrogen production
更新于2025-09-04 15:30:14
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Green synthesis of g-C <sub/>3</sub> N <sub/>4</sub> -Pt catalyst and application to photocatalytic hydrogen evolution from water splitting
摘要： The g-C3N4-Pt photocatalyst was successfully prepared by the combination of a biosynthesis method and sol deposition, which were used for hydrogen evolution from water splitting. The layers of g-C3N4 are thinned and the Pt nanoparticles simultaneously become tightly bound to g-C3N4 by secondary calcination in the process of synthesizing the g-C3N4-Pt photocatalyst. Analysis of the morphological structure and instrumental characterization of the optical performance revealed that the Pt nanoparticles were successfully loaded and well dispersed on the surface of g-C3N4. Furthermore, the absorption wavelength range of the g-C3N4-Pt photocatalyst in visible light was widened and the absorption increased. The activity and photostability of the g-C3N4-Pt photocatalyst for hydrogen evolution under visible light irradiation (λ≥420 nm) were excellent. The rate of H2 evolution reached 582.4 mmol h?1 g?1, and the quantum efficiency (QE) reached 2.70% at 420 nm.
关键词： green synthesis,hydrogen evolution,visible-light photocatalysis,G-C3N4-Pt photocatalyst
更新于2025-09-04 15:30:14