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Boosting the photocatalytic ability of g-C3N4 for hydrogen production by Ti3C2 MXene quantum dots
摘要： The big challenging issues in photocatalytic H2 evolution are efficient separation of the photoinduced carriers, the stability of the catalyst, enhancing quantum efficiency and requiring photoinduced electrons enrich on photocatalysts’ surface. Herein, Ti3C2 MXene quantum dots (QDs) possess the activity of Pt as co-catalyst in promotion the photocatalytic H2 evolution to form heterostructure with g-C3N4 nanosheets (NSs) (denoted as g-C3N4@Ti3C2 QDs). The photocatalytic H2 evolution rate of g-C3N4@Ti3C2 QDs composite with an optimized Ti3C2 QDs loading amounts (100 mL) is nearly 26, 3 and 10 times higher than pristine g-C3N4 NSs, Pt/g-C3N4, Ti3C2 MXene sheet/g-C3N4, respectively. The Ti3C2 QDs increase the specific surface area of g-C3N4 and boost the density of active site. Besides, metallic Ti3C2 QDs possess excellent electronic conductivity, causing the improvement of carrier transfer efficiency.
关键词： Ti3C2 MXene quantum dots,Photocatalytic H2 production,g-C3N4 nanosheets,co-catalysts
更新于2025-09-19 17:13:59
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A Review on Quantum Dots Modified g-C3N4-Based Photocatalysts with Improved Photocatalytic Activity
摘要： In the 21st century, the development of sustainable energy and advanced technologies to cope with energy shortages and environmental pollution has become vital. Semiconductor photocatalysis is a promising technology that can directly convert solar energy to chemical energy and is extensively used for its environmentally-friendly properties. In the field of photocatalysis, graphitic carbon nitride (g-C3N4) has obtained increasing interest due to its unique physicochemical properties. Therefore, numerous researchers have attempted to integrate quantum dots (QDs) with g-C3N4 to optimize the photocatalytic activity. In this review, recent progress in combining g-C3N4 with QDs for synthesizing new photocatalysts was introduced. The methods of QDs/g-C3N4-based photocatalysts synthesis are summarized. Recent studies assessing the application of photocatalytic performance and mechanism of modification of g-C3N4 with carbon quantum dots (CQDs), graphene quantum dots (GQDs), and g-C3N4 QDs are herein discussed. Lastly, challenges and future perspectives of QDs modified g-C3N4-based photocatalysts in photocatalytic applications are discussed. We hope that this review will provide a valuable overview and insight for the promotion of applications of QDs modified g-C3N4 based-photocatalysts.
关键词： organic pollutant photodegradation,H2 production,graphitic carbon nitride (g-C3N4),photocatalysis,CO2 reduction,quantum dots (QDs)
更新于2025-09-19 17:13:59
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Type-II/type-II band alignment to boost spatial charge separation: A case study of g-C3N4 quantum dot/a-TiO2/r-TiO2 for highly efficient photocatalytic hydrogen and oxygen evolution
摘要： Efficient spatial charge separation and transfer that are critical factors for solar energy conversion primarily depend on the energetic alignment of the band edges at interfaces in heterojunctions. Herein, we first report that constructing 0D/0D type-II(T-II)/T-II heterojunction is an effective strategy to ingeniously achieve long-range charge separation by taking a ternary heterojunction of TiO2 and graphitic carbon nitride (g-C3N4) as a proof-of-concept. Incorporating g-C3N4 quantum dots (QCN), as the third component, into the commercial P25 composed of anatase (a-TiO2) and rutile (r-TiO2) can be realized via simply mixing the commercially Degussa P25 and QCN solution followed by heat treatment. The strong coupling and matching band structures among a-TiO2, r-TiO2 and QCN result in the construction of novel T-II/T-II heterojunctions, which would promote the spatial separation and transfer of photogenerated electrons and holes. Moreover, QCN plays a key role in reinforcing light absorption. Specially, the unique 0D/0D architecture possesses the advantages of abundant active sites for photocatalytic reaction. As a result, the optimized QCN/a-TiO2/r-TiO2 heterojunctions exhibit enhanced photocatalytic H2 and O2 evolution, especially the hydrogen evolution rate (49.3 μmol h?1) is 11.7 times that of bare P25 under visible light irradiation, and sufficiently catalytic stability as evidenced by the recycling experiments. The remarkable enhanced photocatalytic activity can be attributed to the synergistic effects of the energy level alignment at interfaces, the dimensionality and component of the heterojunctions. This work provides a stepping stone towards the design of novel heterojunctions for photocatalytic water splitting.
关键词： type-II/type-II band alignment,0D/0D heterojunction,photocatalytic water splitting,g-C3N4 quantum dots,TiO2
更新于2025-09-19 17:13:59
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Polyaniline supported g-C3N4 quantum dots surpass benchmark Pt/C: Development of morphologically engineered g-C3N4 catalysts towards a??metal-freea?? methanol electro-oxidation
摘要： In spite of being one of the most promising energy conversion devices, the state of the art in the efficient application of direct methanol fuel cell is far from being optimal mostly because of its heavy reliance on expensive Pt anode that suffers from easy CO poisoning. Here, in this work for the first time in literature, we have explored the catalytic efficacy and improved mass activity of morphologically engineered metal-free graphitic carbon nitride towards methanol oxidation. The 2D nano-sheets, 1D nano-rods, and 0D quantum dots of graphitic carbon nitride are successfully prepared from bulk by a thermo-chemical etching process. The materials are thoroughly characterized with the help of X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, luminescence study and are studied for methanol oxidation reaction in basic condition with the help of cyclic voltammetry. Among the three different dimensional g-C3N4 materials, the quantum dots show higher methanol oxidation activity due to its abundant edges in nano morphology and maximum atomic percentages of active site of pyridinic N. The 0D g-C3N4 when supported on conducting polyaniline, not only shows higher electrocatalytic methanol oxidation activity than the commercial Pt/C but also demonstrates excellent CO tolerance to be a suitable and applicable metal-free anode catalyst in direct methanol fuel cell applications. The electrostatic interaction between 0D g-C3N4 and conducting polyaniline (PANI) fibres may have improved the electrical conductivity and methanol adsorption of CNQD-PANI electrocatalyst and also played a role in oxidizing the adsorbed CO to upsurge the CO tolerance.
关键词： Nano-rods,Metal-free electrocatalysis,Methanol oxidation reaction,Quantum dots,g-C3N4,Nano-sheets
更新于2025-09-19 17:13:59
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Broadband Photocatalysts Enabled by 0D/2D Heterojunctions of Near-Infrared Quantum Dots/Graphitic Carbon Nitride Nanosheets
摘要： A heterojunction made of 0D near-infrared (NIR)-responsive PbS@CdS@ZnS core@shell@shell quantum dots (PCZ QDs) and 2D graphitic carbon nitride (g-C3N4) nanosheets was rationally constructed herein. In addition to some typical advantages of 0D/2D composites, such as short required charge-diffusion distance and high charge mobility, our designed PCZ QDs/g-C3N4 photocatalysts offer additional beneficial features. The broadband optical absorption of high-quality PCZ QDs highly dispersed on g-C3N4 nanosheets and their strong interaction yield efficient charge transfer between them and endow PCZ QDs/g-C3N4 with high photocatalytic activity from ultraviolet to NIR regions. With the optimized QDs loading levels, the achieved, normalized rate constant is higher than the best-reported value for NIR-driven photocatalysis. PCZ QDs/g-C3N4 possesses good recycling performance and no metal release was detected in the solution after photocatalysis. This work highlights the great potential of QDs/g-C3N4 0D/2D photocatalysts in realizing high-efficiency broadband photocatalysis and functional optoelectronic devices for full solar spectrum exploitation.
关键词： quantum dots,g-C3N4,NIR-responsive,charge transfer,broadband photocatalyst
更新于2025-09-19 17:13:59
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Construction of morphology-controlled nonmetal 2D/3D homojunction towards enhancing photocatalytic activity and mechanism insight
摘要： Highlights ? A novel nonmetal 2D/3D g-C3N4 homojunction was constructed via the facile surface in-situ polymerization process. ? The nonmetal 2D/3D g-C3N4 homojunction displayed the dramatically enhanced photocatalytic performance for degrading TC-HCl. ? The improved transfer and separation efficiency of charge carriers resulted from synergetic effect of 2D-3D structural coupling and energy band controlling. ? This work develops a feasible exemplificative strategy for fabricating new morphology-controlled at the interface between structural units owing to the matching chemical and electronic structures, nevertheless it still is difficult to fabricate the morphology-controlled nonmetal homojunction. Herein, a nonmetal 2D/3D homojunction is constructed via the facile surface Constructing homojunction is more favorable to transfer and separation of charge carriers nonmetal homojunctions to improve photocatalytic activity microspheres, mainly attributing to the improved transfer and separation efficiency of charge homojunction displays the dramatically enhanced photocatalytic performance for degrading tetracycline hydrochloride (TC-HCl) compared with single 2D CN nanosheets and 3D CC carriers resulted from synergetic effect of 2D-3D structural coupling and energy band controlling. Moreover, the important degradation pathway, intermediate products and surface of 2D g-C3N4 (2D CN) nanosheets. The obtained nonmetal 2D/3D CN/CC in-situ polymerization process, where 3D g-C3N4 (3D CC) microspheres tightly anchor on the photocatalytic mechanism are investigated in detail. This work develops a feasible exemplificative strategy for fabricating new morphology-controlled nonmetal homojunction to improve photocatalytic activity.
关键词： Degradation mechanism,TC-HCl,Nonmetal homojunction,g-C3N4,Morphology-controlled
更新于2025-09-19 17:13:59
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0D/2D plasmonic Cu2-xS/g-C3N4 nanosheets harnessing UV-vis-NIR broad spectrum for photocatalytic degradation of antibiotic pollutant
摘要： Localized surface plasmon resonances (LSPRs) are usually achieved by some small grains of noble metal (Au, Ag et al.) to enhances the light absorption and charge carrier’s concentration of photocatalysts, but the wide application of noble metals is limited by their high cost. Here, we report the preparation of 0D/2D plasmonic Cu2-xS/g-C3N4 nanosheets (CSCNNs) and the utilization of LSPRs generated from Cu2-xS nanodots instead of noble metals to improve the photocatalytic activity for degradation of typical antibiotic levofloxacin (LVX). One-step hydrothermal method was employed to grow the highly effective in increasing the light absorption in near infrared (NIR) region and the theoretical analysis of band structure reveals the efficient separation and transmission mechanism of verify the strong light absorption capacity and longer carriers’ lifetime for CSCNNs. The dispersed Cu2-xS nanodots on the g-C3N4 nanosheets. Various characterization techniques region. Consequently, efficient photocatalytic degradation of LVX under full solar photogenerated electrons and holes. More importantly, LSPRs has been proved to be finite difference time domain (FDTD) simulations demonstrated that Cu2-xS LSPR-induced electromagnetic field in g-C3N4 nanosheets was far stronger than that of Ag and Au in NIR efficient LSPR photocatalysis system for treatment of antibiotic wastewater or other spectrum (UV-vis-NIR) can be achieved for CSCNNs. This work will lead to a cheap and photocatalytic applications.
关键词： levofloxacin degradation,Localized surface plasmon resonances,Cu2-xS,g-C3N4
更新于2025-09-19 17:13:59
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In-situ Homodispersely Immobilization of Ag@AgCl on Chloridized g-C3N4 Nanosheets as an Ultrastable Plasmonic Photocatalyst
摘要： Despite their impressive plasmonic photocatalytic activity, nanosized silver and silver halides always suffer from serious agglomeration and photocorrosion, thus are severely restricted in the practical wastewater restoration applications. The design and realization of plasmonic heterojunction nanostructures is an effective way to solve this stability problem, yet the ideal plasmonic catalyst dispersion and immobilization remains a great challenge. In this work, a highly immobilized Ag@AgCl/g-C3N4 plasmonic photocatalyst was developed through a rational in-situ implanting approach, in which the Ag can be homodispersely distributed and strongly coupled with prefixed Cl sites on g-C3N4 nanosheets (CNNS). The X-ray diffraction (XRD) pattern, X-ray photoelectron spectroscopy (XPS) spectra and element mapping images clearly proved the homodispersely distribution of nanosized Ag@AgCl on the CNNS. The optimal Ag@AgCl-3/CNNS plasmonic photocatalyst with a narrow band gap of 2.45 eV and large specific surface area of 52.9 m2/g performs well in model pharmaceutical wastewater bleaching reactions under visible light. More importantly, the Ag@AgCl-3/CNNS show good stability compared with the conventional inhomogeneously coupled AgCl/g-C3N4 control as verified by their ultralow silver leakage rate in water (0.00152 mg/g·d, accounts 6.9% that of the control) and a much lower corrosion current density (Icorr = 1.63 vs. 3.45 μA), recorded by Tafel slopes. The synergetic effect of surface plasmon resonance effect of nanosized Ag@AgCl with strong visible light harvesting ability and strong coupling between Ag@AgCl and exfoliated porous g-C3N4 nanosheets can support the fast separation of photogenerated electron?hole pairs, thus significantly improving the photocatalytic efficiency in the bleaching of antibiotic pollutants and bacteria. This work affords the great potential of the rational in-situ implanting design for high-performance and stable plasmonic photocatalysts.
关键词： silver leakage control,plasmonic photocatalyst,g-C3N4,Ag@AgCl,ultrastable immobilization
更新于2025-09-19 17:13:59
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Doubly Q-switched Tm:YAP laser with g-C3N4 saturable absorber and AOM
摘要： Two-dimensional (2D) graphitic carbon nitride (g-C3N4) was fabricated as saturable absorber (SA) and the nonlinear optical absorption properties were measured. A laser-diode (LD) pumped doubly Q-switched Tm-doped yttrium-aluminium perovskite YAlO3 (Tm:YAP) laser at 2 μm with g-C3N4 and acousto-optic modulator (AOM) is presented for the ?rst time to the best of our knowledge. Under an absorbed pump power of 5.34 W, the minimum pulse width of 239 ns and the maximum peak power of 1146 W were obtained by the doubly Q-switched laser. In comparison with the singly Q-switched laser using g-C3N4 SA or AOM, the dual-loss-modulated Q-switched laser could generate shorter pulse width and higher peak power. The maximum pulse width compression ratio was 4.48 and the highest peak power enhancement factor was 241. The experimental results indicated that 2D g-C3N4 SA is potential in Q-switched laser at 2 μm and the doubly Q-switched technology is a useful way to compress the pulse width and improve the peak power.
关键词： Pulse width,Doubly Q-switch,g-C3N4,Peak power,2 μm waveband
更新于2025-09-19 17:13:59
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Metal-free carbon nitride with boosting photo-redox ability realized by the controlled carbon dopants
摘要： Metal-free carbon nitride with controlled carbon dopants (ACCN) was synthesized by one-step copolymerization of dicyandiamide (DCD) and ammonium citrate (AC). The obtained ACCN possesses narrower band gap compared to pure graphitic carbon nitride (CN), contributing to broader utilization region of visible light. It exhibits downshifted conduction band and valence band potential with the increased addition of AC. Carbon atoms replace the bridging nitrogen atoms in the framework of ACCN during calcination process, which greatly increase its electrical conductivity and charge separation efficiency. In addition, nitrogen defects and some carbon species linked to the introduced carbon atoms are detected in ACCN. They can also serve as electrons sink to promote the separation of electron-hole pairs. As a consequence, ACCN possesses improved redox ability in the degradation of sulfamethazine (SM2) under visible light. The removal ratio by optimal ACCN achieves 81% in 60 min and its reaction apparent rate constant (0.0277 min?1) is 6.6 times higher than that of CN (0.0042 min?1). Furtherly, the mechanism and reaction process during the photocatalytic degradation are studied specifically. This work provides a facile and green strategy to prepare nonmetal modified CN with boosting photo-redox ability for pollutants treatment.
关键词： g-C3N4,Charge separation,Photocatalysis,Carbon dopants,Pollutants degradation,Ammonium citrate
更新于2025-09-16 10:30:52