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CO2-Triggered Reversible Phase Transfer of Graphene Quantum Dots for Visible Light-Promoted Amines Oxidation
摘要： Emerging as novel photoluminescent nanomaterials, carbon dots have attracted increasing attentions in photocatalytic application such as hydrogen evolution, carbon dioxide reduction, pollutants degradation and organic synthesis. However, it is always a cumbersome process to seperate the carbon dots from the reaction system, which may limit their application in photocatalysis. Here, we report a graphene quantum dot with CO2-switchable reversible phase transfer performance via a facile surface functionlization approach. The mechanism of this hydrophilicity and hydrophobicity alteration involves protonation-deprotonation transformation and reversibly formation of hydrophilic bicarbonates salts when bubbling and removal of CO2. Afterwards, the obtained graphene quantum dot is utilized as a visible light photocatalyst for oxidative coupling of amines. Our photocatalyst demonstrates an excellent catalytic efficiency with both high reaction conversion and selectivity being achieved. Furthermore, graphen quantum dot could be recycled via a simple CO2 bubbling method.
关键词： graphene quantum dot,reversible phase transfer,visible light photocatalysis,CO2-switchable,amines oxidation
更新于2025-09-19 17:13:59
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Plasmonic Switching of the Reaction Pathway: Visible‐Light Irradiation Varies the Reactant Concentration at the Solid–Solution Interface of a Gold–Cobalt Catalyst
摘要： Product selectivity of alkyne hydroamination over catalytic Au2Co alloy nanoparticles (NPs) can be made switchable by a light-on/light-off process, yielding imine (cross-coupling product of aniline and alkyne) under visible-light irradiation, but 1,4-diphenylbutadiyne in the dark. The low-flux light irradiation concentrates aniline on the catalyst, accelerating the catalytic cross-coupling by several orders of magnitude even at a very low overall aniline concentrations (1.0 X 10@3 mol L@1). A tentative mechanism is that Au2Co NPs absorb light, generating an intense fringing electromagnetic field and hot electrons. The sharp field-gradient (plasmonic optical force) can selectively enhance adsorption of light-polarizable aniline molecules on the catalyst. The light irradiation thereby alters the aniline/alkyne ratio at the NPs surface, switching product selectivity. This represents a new paradigm to modify a catalysis process by light.
关键词： product selectivity,reaction pathway,selective adsorption,visible-light photocatalysis,plasmonic metal nanoparticles
更新于2025-09-19 17:13:59
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Novel N/Carbon Quantum Dots-Modified MIL-125(Ti) Composite for Enhanced Visible Light Photocatalytic Removal of NO
摘要： A highly efficient and stable photocatalysts were synthesized at room temperature by modifying MIL-125(Ti) with N-doped carbon quantum dots (N/CM(Ti)). The N/CM(Ti) with 2.5 Vol% N doped carbon quantum dots (N/CQDs) had the best light absorption and visible light photocatalytic nitrogen oxide (NO) removal efficiency (approximately 49%). It was found through X-ray photoelectron spectroscopy analysis that the N-Ti-O bond was formed in the 2.5 Vol% N/CM(Ti), which is more conducive to charge transfer. Photocurrent and electrochemical impedance data also showed that the carrier separation efficiency of 2.5 Vol% N/CM(Ti) was significantly superior to that of MIL-125(Ti). In addition, the TiIII-TiIV of MIL-125(Ti) acts as the active center for photocatalytic removal of NO. Two possible electron migration paths were proposed: electron transfer from N/CQDs to TiIII-TiIV center of MIL-125(Ti) due to the photoinduced electron transfer property of N/CQDs, and absorption of UV light generated from the N/CQDs by the terephthalic acid ligand followed by electron transfer to metal active sites for photocatalytic removal of NO.
关键词： MIL-125(Ti),Visible light,Photocatalysis,NO removal,N-doped carbon quantum dots
更新于2025-09-19 17:13:59
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Highly Efficient UV–Visible Photocatalyst from Monolithic 3D Titania/Graphene Quantum Dot Heterostructure Linked by Aminosilane
摘要： As rapidly growing environmental pollution demands the development of efficient photocatalytic materials, tremendous attention has been drawn to TiO2, a widely used photocatalytic material with cost-effectiveness, stability, and outstanding reactivity. To maximize its photocatalytic efficiency by enhancing the photogenerated charge separation, lowering the intrinsically large bandgap (3.2 eV) of TiO2 is a key problem to be overcome. Herein, a new design is reported for an efficient photocatalyst realized by heterostructuring a 3D nanostructured TiO2 monolith (3D TiO2) and graphene quantum dots (GQDs) through using 3-aminopropyltriethoxysilane (APTES) as a linker. The incorporation of APTES between the TiO2/GQD interface enables the formation of a charge injection-type heterostructure, as confirmed by transient absorption spectroscopy, providing improvement of both visible absorption and charge separation. As a result, the heterostructure exhibits a 242% enhanced photocatalytic performance compared to that of nonheterostructured 3D TiO2 under visible irradiation, demonstrating its promising potential for practical photocatalytic applications in environmental remediation.
关键词： TiO2/GQD heterostructure,graphene quantum dots,visible light photocatalysis,charge injection,3D nanostructured TiO2
更新于2025-09-19 17:13:59
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Highly Efficient Cu Induced Photocatalysis for Visible-light Hydrogen Evolution
摘要： Coinage metal (Au, Ag, Cu) induced photocatalysis has emerged as a promising strategy in developing visible-light responsive photocatalysts. Though much progress has been made, yet researchers in this field faced great challenges from both low efficiency and rigorously relying on noble metal Au. In this work, a series of Cu/SrTiO3 with gradually increased Cu particle size from 2.8 to 7.7 nm were successfully prepared with in situ multistep photodeposition method. A highly efficient visible-light photocatalytic H2 evolution is achieved over 0.5 wt% Cu/SiTiO3 with an average Cu particle size of 3.9 nm, which reaches 5 fold as compared with its counterpart Au. As far as we know, it is the first time that Cu induced visible-light photocatalytic water splitting show prominently superior activity than that of Au under the same conditions. Further study reveals that the increase of Cu particle size effectively mitigates Fano interference between interband transition and localized surface plasmon resonance (LSPR), which extends the photo-induced carriers lifetime. The discovery here is supposed to ignite great research interests in exploring efficient and nonprecious Cu induced visible-light photocatalysis.
关键词： Particle size effect,Cu nanoparticles,Visible-light photocatalysis,Fano interference
更新于2025-09-10 09:29:36
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Highly efficient visible-light-assisted photocatalytic hydrogen generation from water splitting catalyzed by Zn0.5Cd0.5S/Ni2P heterostructures
摘要： Development of heterostructured photocatalysts which can facilitate spatial separation of photo-generated charge carriers is crucial for achieving improved photocatalytic H2 production. Consequently, herein, we report the synthesis of Zn0.5Cd0.5S/Ni2P heterojunction photocatalysts with varying amount of Ni2P, 0.5 (S1), 1 (S2), 3 (S3), 5 (S4) and 10wt% (S5) for the efficient visible-light-assisted H2 generation by water splitting. The heterostructures were characterized thoroughly by PXRD, FE-SEM, EDS, HR-TEM and XPS studies. FE-SEM and HR-TEM analyses of the samples unveiled the presence of Zn0.5Cd0.5S microspheres composed of smaller nanocrystals with the surface of the microspheres covered with Ni2P nanosheets and the intimate contact between the Zn0.5Cd0.5S and the Ni2P. Further, visible-light-assisted photocatalytic investigation of the samples showed excellent water splitting activity of the heterostructure, Zn0.5Cd0.5S/1wt%Ni2P (S2) with very high H2 generation rate of 21.19 mmol h?1 g?1 and the AQY of 21.16% at 450 nm with turnover number (TON) and turnover frequency (TOF) of 251,516 and 62,879 h?1 respectively. Interestingly, H2 generation activity of S2 was found to be about four times higher than that of pure Zn0.5Cd0.5S (5.0 mmol h?1 g?1) and about 240 times higher than that of CdS/1wt%Ni2P. The enhanced H2 generation activity of S2 has been attributed to efficient spatial separation of photo-generated charge carriers and the presence of highly reactive Ni2P sites on the surface of Zn0.5Cd0.5S microspheres. A possible mechanism for the enhanced photocatalytic H2 generation activity of Zn0.5Cd0.5S/1wt%Ni2P (S2) has been proposed and is further supported by photoluminescence and photocurrent measurements. Furthermore, the catalyst, S2 can be recycled for several cycles without significant loss of catalytic activity and photostability. Remarkably, the H2 generation activity of S2 was found to be even higher than the reported examples of ZnxCd1-xS doped with noble metal cocatalysts. Hence, the present study highlights the importance of Zn0.5Cd0.5S/Ni2P heterostructures based on non-noble metal co-catalyst for efficient visible-light-driven H2 production from water splitting.
关键词： Heterostructure,Transition metal phosphide,H2 generation,Visible-light photocatalysis,Zn0.5Cd0.5S nanostructures
更新于2025-09-10 09:29:36
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Tuning in BiVO4/Bi4V2O10 porous heterophase nanospheres for synergistic photocatalytic degradation of organic pollutants
摘要： Heterophase junction construction is a powerful means of inhibiting recombination of photoinduced charge carriers. Herein, we prepared BiVO4/Bi4V2O10 porous heterophase nanospheres assembled by nanoflakes through a facile solvothermal process. The crystal structure of the porous nanospheres can be easily regulated from mixed phase of BiVO4 and Bi4V2O10 to pure BiVO4 by changing the solvothermal reaction time. The formation of heterophase junction BiVO4/Bi4V2O10 can greatly enhance the transfer and separation rate of photogenerated charge carriers. Meanwhile, the porous nanoflake-based nanosphere structure can enhance visible light utilization and organic pollutants adsorption. Benefiting from the synergy effects of these positive factors, the optimal BiVO4/Bi4V2O10 exhibits excellent visible light photocatalytic performance and cycling capability for the degradation of organic pollutants.
关键词： porous nanospheres,heterophase junction,pollutants degradation,BiVO4/Bi4V2O10,visible light photocatalysis
更新于2025-09-10 09:29:36
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Dual Catalytic Switchable Divergent Synthesis: An Asymmetric Visible-light Photocatalytic Approach to Fluorine-containing γ-Keto Acid Frameworks
摘要： Herein, we describe a novel and efficient method for constructing a series of fluorine-containing γ-keto acid derivatives through combining visible-light photoredox catalysis and chiral Lewis acid catalysis. With this dual catalytic strategy, a variety of chiral γ-keto amides containing a gem-difluoroalkyl group and a series of fluorine-containing α,β-unsaturated-γ-keto esters were successfully constructed with high stereoselectivities, respectively. A series of experiments showed that the chemoselectivity of this process was highly dependent on the fluorine reagents besides the Lewis acid catalysts. This approach facilitates rapid access to γ-keto acid derivatives, an important class of precursors for pharmaceuticals, plasticizers, and various other additives.
关键词： γ-keto acid derivatives,chiral Lewis acid catalysis,visible-light photocatalysis,asymmetric difluoroalkylation
更新于2025-09-10 09:29:36
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2D-Bi<sub>2</sub>MoO<sub>6</sub>/2D-g-C<sub>3</sub>N<sub>4</sub> nanosheet heterojunction composite: synthesis and enhanced visible light photocatalytic mechanism
摘要： In this study, a novel 2D Bi2MoO6 nanosheet/2D g-C3N4 nanosheet heterojunction composite was fabricated through hydrothermal strategy. Afterwards, physicochemical properties of the composite were systematically detected by series of measurements. In addition, photocatalytic activity was evaluated by degradation of Rhodamine B, methylene blue, Amido black 10B and malachite green. Results showed that Bi2MoO6/g-C3N4 played higher photocatalytic efficiency than that of pristine Bi2MoO6 and g-C3N4 sample under visible irradiation. This phenomenon could be attributed to the combination of Bi2MoO6 and g-C3N4 as well as unique 2D/2D heterostructure. Also, the as-fabricated Bi2MoO6/g-C3N4 composite possessed higher surface area, narrower band gap energy, larger electron transport capability and longer charge carrier lifetime. Furthermore, the enhanced visible light driven photocatalytic mechanism was proposed and confirmed, which was mainly ascribed to the Z-scheme structure. That was, the photogenerated electrons (e-) in the CB of Bi2MoO6 and photogenerated holes (h+) in the VB of g-C3N4 would combine with each other quickly, so that the e- in the CB of g-C3N4 and h+ in the VB of Bi2MoO6 participated in reduction and oxidation reactions, respectively. Also, this composite exhibited superior physicochemical stability. Hence, it would be applied in advanced wastewater treatment.
关键词： Nanosheet heterojunction,Bi2MoO6/g-C3N4,Visible light photocatalysis,Z-Scheme,2D/2D
更新于2025-09-09 09:28:46
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Optimization, kinetics and thermodynamics of photocatalytic degradation of Acid Red 1 by Sm-doped CdS under visible light
摘要： Sm-doped CdS nanoparticles were synthesized through an ultrasound-assisted co-precipitation method and their photocatalytic efficiency was investigated by applying them to photodegradation of Acid Red 1 (AR1) under visible light. The effect of the operational factors on the photocatalytic process was systematically evaluated using response surface methodology. Under the optimal conditions ([AR1]0= 15 mg L-1, [2% Sm-CdS]0= 1 g L-1, pH= 4 and t= 94 min), more than 83% of the AR1 molecules were degraded. The kinetics of the process was well described by the Langmuir-Hinshelwood’s pseudo-first-order model (kapp= 0.0163 min-1). Furthermore, thermodynamics of the process was demonstrated by the activated complex theory of Eyring, which declared that the photocatalytic process is endothermic and nonspontaneous in the temperature range of 25–45°C. In addition, the main products and intermediates of AR1 degradation were determined by the GC-MS technique.
关键词： Sm-doped CdS,Thermodynamics,Visible light photocatalysis,Kinetics,Acid Red 1,RSM
更新于2025-09-09 09:28:46