- 标题
- 摘要
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- 实验方案
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Rational Design of Graphic Carbon Nitride Copolymers by Molecular Doping for Visible-Light-Driven Degradation of Aqueous Sulfamethazine and Hydrogen Evolution
摘要： Carbon nitride is a promising metal-free visible light driven photocatalyst and sustainable material for address contaminant pollution and water splitting. However, the insufficient visible light absorption and fast charge recombination of carbon nitride have limited its practical application. Herein, the self-assembly carbon nitride (denoted as TCN) by molecular doping copolymerization of urea and 2-thiobarbitucid acid (TA) was prepared. XPS and elemental analytical results indicated that TA was doped in the framework of carbon nitride successfully. The self-assembly copolymerization would result in the change of morphology, intrinsic electron and band structure of carbon nitride. Theoretical calculations and experiments confirm that the band gap of TCN could be adjusted by changing the amount of 2-thiobarbitucid acid. Moreover, the efficiency of charge carrier transfer and separation was greatly enhanced. As a result, the optimized photocatalyst TCN-0.03 exhibited superior activity with a high reaction rate of 0.058 min-1 for the degradation of sulfamethazine under visible light irradiation, which is 4.2 times higher than that of urea based carbon nitride (U-CN). As a multifunctional photocatalyst, TCN-0.03 showed enhanced activity for hydrogen production (55 μmol h-1), which was 11 times higher than U-CN. The apparent quantum efficiency reached to 4.8% at 420 nm. A possible mechanism was proposed to explain the photocatalytic reaction process. This work provides insight into the rational design of modified carbon nitride by other organic monomers copolymerization to enhance the photocatalytic activity.
关键词： Photocatalytic degradation,Photocatalytic hydrogen evolution,Carbon nitride,Charge carriers transfer,Molecular doping copolymerization
更新于2025-09-09 09:28:46
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Cooperative effect between BaTiO3 and CaFe2O4 in a cocatalyst-free heterojunction composite for improved photochemical H2 generation
摘要： A series of novel BaTiO3/CaFe2O4 heterojunction composites with different weight ratios of CaFe2O4 vs BaTiO3 was successfully fabricated by sonication-calcination method using the pre-prepared BaTiO3 and CaFe2O4 powders synthesized in hydrothermal and sol-gel methods, respectively. The composites were well characterized using XRD, UVevis DRS, SEM, TEM, EDS and XPS to substantiate that BaTiO3 and CaFe2O4 coexist in the heterojunction composite. The highest photocatalytic hydrogen generation rate was obtained for BaTiO3/CaFe2O4 (40 wt%) compared to either of its individual counterparts and this improvement indicated the existence of a cooperative effect between BaTiO3 and CaFe2O4 in the heterojunction. Based on UV-vis-DRS, photoluminescence and time-resolved fluorescence lifetime measurements, the cooperative effect between BaTiO3 and CaFe2O4 originated from the improved photoresponse in the visible light region and efficient separation of the photogenerated electronehole pairs augmenting their availability for the photocatalytic reaction. A plausible photocatalytic mechanism was also deduced using electrochemical impedance spectroscopy measurements, describing the migration direction of the separated charge carriers. Moreover, the best composite BaTiO3/CaFe2O4 (40 wt %) exhibited fairly stable photoactivity for H2 production using the sacrificial agent (Na2S and Na2SO3) without the assistance of any noble metals as cocatalysts.
关键词： Cocatalyst free,BaTiO3/CaFe2O4 composite,Hydrogen evolution,Sonication-calcination method,Heterojunction
更新于2025-09-09 09:28:46
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Growth of 1T’ MoTe <sub/>2</sub> by Thermally-Assisted Conversion of Electrodeposited Tellurium Films
摘要： Molybdenum ditelluride (MoTe2) is a transition metal dichalcogenide (TMD) which has two phases stable under ambient conditions, a semiconducting (2H) and semimetallic (1T’) phase. Despite a host of interesting properties and potential applications, MoTe2 is one of the less-studied TMDs, perhaps due its relatively-low abundance in nature or challenges associated with its synthesis, such as the toxicity of most precursors. In this report, we describe the fabrication of thin films of phase-pure 1T’ MoTe2 using pre-deposited molybdenum and electrodeposited tellurium layers, at the relatively low temperature of 450?C. This method allows control over film geometry and over the tellurium concentration during the conversion. The MoTe2 films are characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and electron microscopies. When applied as a catalyst for the hydrogen evolution reaction, the films display promising initial results. The MoTe2 films have a Tafel slope of below 70 mV dec-1 and compare favorably with other MoTe2 catalysts reported in the literature, especially considering the inherently-scalable fabrication method. The variation in electrocatalytic behavior with thickness and morphology of the films is also investigated.
关键词： 1T’ phase,thin-film,hydrogen evolution reaction,Raman spectroscopy,MoTe2,electrocatalysis
更新于2025-09-09 09:28:46
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Round-the-clock Photocatalytic Hydrogen Production with High Efficiency by a Long Afterglow Material
摘要： Long afterglow materials can store and release light energy after illumination. Here, a brick-like, micron-sized Sr2MgSi2O7:Eu2+,Dy3+ long afterglow material is used for hydrogen production via the photocatalytic reforming of methanol under round-the-clock conditions for the first time, achieving a solar-to-hydrogen (STH) conversion efficiency of 5.18%. This material is one of the most efficient photocatalysts and provides the possibility of practical use on a large scale. Its remarkable photocatalytic activity is attributed to its unique carrier migration path and large number of lattice defects. Our findings expand the application scope of long afterglow materials and provide a new strategy to design efficient photocatalysts by constructing trap levels that can prolong carriers’ lifetimes.
关键词： round-the-clock,water,Long afterglow,photocatalytic hydrogen evolution,methanol
更新于2025-09-09 09:28:46
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First Photometric Investigations of the Solar-type Binary FV CVn in Multiple Systems
摘要： FV CVn is a solar-type (G7) eclipsing binary whose analysis has so far been ignored. We observed it from 2014 January to 2018 May. The ?rst photometric and orbital period investigation are presented here, combined with spectroscopic observations obtained by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). The current preliminary solutions show that FV CVn is a new W-subtype contact binary with a mass ratio of q?=?M2/M1?=?2.44(±0.20) and a temperature difference of ? = - K. The orbital period investigation suggests that a cyclic variation of A?=?0.0184(±0.0034) days and P3?=?17.65(±0.076) years exists in FV CVn. This cyclic variation is analyzed for the light-travel-time effect (LTTE) via the presence of a third body with a minimum mass of M3min?=?0.73(±0.018) Me, and an orbital semimajor axis shorter than 5.27(±1.62) au. This is in agreement with the presence of a large quantity of a third light in the system. Photometric solutions suggest that the third body contributes about 26.4(±6.3)% in Rc, and 29.0(±5.9)% in Ic to the total light of the multiple system. The additional component may play an important role in the origin and evolution of central close binary. New radial velocities are needed in the future to check the accuracy of the absolute parameters.
关键词： stars: individual (FV CVn),stars: binaries (including multiple): close,stars: evolution,stars: binaries: spectroscopic,stars: binaries: eclipsing,stars: solar-type
更新于2025-09-09 09:28:46
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Propagation of Optical Coherence Vortex Lattices in Turbulent Atmosphere
摘要： Propagation properties in the turbulence atmosphere of the optical coherence vortex lattices (OCVLs) are explored by the recently developed convolution approach. The evolution of spectral density distribution, the normalized M2-factor, and the beam wander of the OCVLs propagating through the atmospheric turbulence with Tatarskii spectrum are illustrated numerically. Our results show that the OCVLs display interesting propagation properties, e.g., the initial Gaussian beam distribution will evolve into hollow array distribution on propagation and ?nally becomes a Gaussian beam spot again in the far ?eld in turbulent atmosphere. Furthermore, the OCVLs with large topological charge, large beam array order, large relative distance, and small coherence length are less affected by the negative effects of turbulence. Our results are expected to be used in the complex system optical communications.
关键词： optical coherence vortex lattices,evolution properties,atmospheric turbulence,free-space optical communications
更新于2025-09-04 15:30:14
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Round‐the‐clock Photocatalytic Hydrogen Production with High Efficiency by a Long Afterglow Material
摘要： Long afterglow materials can store and release light energy after illumination. Here, a brick-like, micron-sized Sr2MgSi2O7:Eu2+,Dy3+ long afterglow material is used for hydrogen production via the photocatalytic reforming of methanol under round-the-clock conditions for the first time, achieving a solar-to-hydrogen (STH) conversion efficiency of 5.18%. This material is one of the most efficient photocatalysts and provides the possibility of practical use on a large scale. Its remarkable photocatalytic activity is attributed to its unique carrier migration path and large number of lattice defects. Our findings expand the application scope of long afterglow materials and provide a new strategy to design efficient photocatalysts by constructing trap levels that can prolong carriers’ lifetimes.
关键词： round-the-clock,water,Long afterglow,photocatalytic hydrogen evolution,methanol
更新于2025-09-04 15:30:14
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Weak convergence rates for stochastic evolution equations and applications to nonlinear stochastic wave, HJMM, stochastic Schr?dinger and linearized stochastic Korteweg–de Vries equations
摘要： We establish weak convergence rates for noise discretizations of a wide class of stochastic evolution equations with non-regularizing semigroups and additive or multiplicative noise. This class covers the nonlinear stochastic wave, HJMM, stochastic Schr¨odinger and linearized stochastic Korteweg–de Vries equation. For several important equations, including the stochastic wave equation, previous methods give only suboptimal rates, whereas our rates are essentially sharp.
关键词： stochastic evolution equations,multiplicative noise,additive noise,linearized stochastic Korteweg–de Vries equation,stochastic Schr¨odinger,non-regularizing semigroups,weak convergence rates,HJMM,stochastic wave equation
更新于2025-09-04 15:30:14
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Steering Charge Transfer for Boosting Photocatalytic H2 Evolution: Integration of Two-dimensional Semiconductor Superiorities and Noble-Metal-free Schottky Junction Effect
摘要： Sunlight-driven photocatalysis holds great promise for alleviating the energy and environmental crises. For the visible-light-driven bare semiconductor, there is an irreconcilable contradiction between the light absorption and strong redox capabilities. Here, we reported a predictable design for improving the photocatalytic performance via regulating the bandgap and accelerating the charge kinetics of the semiconductor. Taken together, utilize two-dimensional (2D) structure to essentially increase the bandgap of the semiconductor for gaining the higher transfer and separation of the photogenerated electron-hole pairs and the stronger redox capabilities; and accelerate charge kinetics via the driving force from the Schottky junction. Meanwhile, the Schottky barrier prevents the photogenerated electrons trapped by a noble-metal-free electron acceptor from dually recombining. Additionally, the energy transfer process of the photocatalytic reaction was also researched in detail, aligning well with the photocatalytic mechanism.
关键词： photocatalytic H2 evolution,2D materials,Schottky junction
更新于2025-09-04 15:30:14
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Fabrication of Heterogeneous Photocatalysts for Insight role of Carbon Nanofibre in Hierarchical WO3/ MoSe2 composite for Enhanced Photocatalytic Hydrogen Generation
摘要： Mimicking the natural photosynthesis system, artificial photocatalysis facilitates effective utilization of solar energy for environmental sustainability and hydrogen energy production. In this work, the robust and efficient carbon fiber has been successfully incorporated into the interface between WO3 nanodots and MoSe2 needles using the facile hydrothermal and solvothermal method. The suitable interfacial contact of heterogeneous photocatalysts plays a significant role in the separation/transfer of interfacial photogenerated electron-hole pairs and hetero-junction. It seems an efficient approach for enhanced photocatalytic performance since the greater area of contact could improve the interfacial rate of charge transfer. The phase structure of prepared WO3 nanodots changed from the monoclinic to hexagonal phase by the addition of co-catalyst. The experimental results exhibited that carbon fiber played a tri-functional role to boost up the photocatalytic activity over MoSe2 nanostructures. It’s not only act as operative co-catalyst but could also serve as the conductive electron bridges, rather than general cocatalyst, to accumulate electrons and encourage the hydrogen generation kinetics over the WO3 photocatalysts. More interestingly, the WO3-1% MoSe2-1.5% carbon fiber and WO3-1%MoSe2 nanocomposites demonstrated the excellent rates of hydrogen evolution 438.7 and 356.2 mmol/g.h, which were 7.6 and 6.17 times higher when compared to that of pure MoSe2, respectively. Under the visible light excitation, the atomically junction encourages fast electron transfer from nanofibers to MoSe2 to suppress the rapid recombination kinetics within WO3 nanodots and extend the lifetime of WO3 charge carrier’s, thereby releasing more photogenerated electrons with higher reducing power for hydrogen evolution. The current work can contribute with new perspectives and mechanistic insight for the design and development of heterogeneous photocatalysts WO3 based nanostructures using the combination of MoSe2 and trifunctional carbon nanofibers for environment and energy harvesting applications.
关键词： Sustainable Environment,Hydrogen Evolution,Carbon nanofibers,Photocatalysis,Nanostructures
更新于2025-09-04 15:30:14