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Role of Pt Loading in the Photocatalytic Chemistry of Methanol on Rutile TiO2(110)
摘要： As a cocatalyst, Pt is well-known for accepting photoexcited electrons and lowering the overpotential of hydrogen production in photocatalysis, being responsible for the enhanced photocatalytic efficiency. Despite the above existing knowledge, the adsorption of reactants on the Pt/photon-absorber (for example, Pt/TiO2) interface, a prerequisite to understand the photocatalytic chemistry, is extremely difficult to investigate mainly due to the complexity of the powdered material and solution environment. Combining ultrahigh vacuum and well-ordered single crystals, we study the photocatalytic chemistry of methanol on Pt loaded rutile TiO2(110) using temperature-programmed desorption (TPD) and ultraviolet photoelectron spectroscopy (UPS). Despite the same photocatalytic chemical products, i.e., formaldehyde and surface hydrogen species, as on Pt-free TiO2(110), the subsequent chemistry of surface hydrogen species and the photocatalytic reaction rate are much different. The bridging hydroxyls desorb as water molecules around 500 K on Pt-free TiO2(110) surface, by contrast, this desorption channel disappears completely and water and molecular hydrogen desorb at much lower temperature (<300 K) after Pt deposition, which can prevent the recombination of hydrogen species with formaldehyde. More importantly, methanol dissociates into methoxy at the Pt/TiO2(110) interface, which is crucial in the photocatalytic chemistry of methanol on TiO2 surfaces since methoxy is a more effective hole scavenger than methanol itself. The photocatalytic chemical reaction rate is increased by nearly one order of magnitude after 0.12 monolayer Pt deposition. This work suggests that Pt loading can promote the dissociation of methanol into methoxy and lower the desorption barrier of molecular hydrogen, which may work cooperatively with separating photoexcited charges to enhance the photocatalytic efficiency. Our work implies the importance of the cocatalysts in affecting the surface structure and adsorption of reactants and products and then improving the photoactivity, in addition to the well-known role in charge separation.
关键词： Titanium Dioxide,Charge Separation,Pt Cocatalyst,Hydrogen Production,Methanol to Methoxy Conversion
更新于2025-09-23 15:21:21
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Constructing 1D CdS nanorod composites with high photocatalytic hydrogen production by introducing the Ni-based cocatalysts
摘要： Various 1D CdS nanorod composites (e.g. NiO/CdS, NiS/CdS and Ni(OH)2/CdS) were constructed by anchoring Ni-based cocatalysts on the surface of CdS nanorods. Photocatalytic reforming of lactic acid in aqueous medium for hydrogen generation using CdS composites was investigated, and Ni(OH)2/CdS sample displayed the best activity. Evidently, Ni(OH)2 cocatalyst can offer a suitable potential position to boost the transfer of photo-generated electrons and much more active sites. Furthermore, the result of LSV curves discloses that the higher photocatalytic activity is due to the smaller onset overpotential, which can accelerate the reduction of protons into H2. This work provides a full comprehension of the mechanism that Ni species cocatalysts improve photocatalytic activity.
关键词： cocatalyst,hydrogen production,CdS nanorods,visible light,Ni-based
更新于2025-09-23 15:21:21
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Improving the Visible-Light Photocatalytic Activity of Graphitic Carbon Nitride by Carbon Black Doping
摘要： Hydrogen production by water splitting and the removal of aqueous dyes by using a catalyst and solar energy are an ideal future energy source and useful for environmental protection. Graphitic carbon nitride can be used as the photocatalyst with visible light irradiation. However, it typically suffers from the high recombination of carriers and low electrical conductivity. Here, we have developed a facile mix-thermal strategy to prepare carbon black-modified graphitic carbon nitrides, which possess high electrical conductivity, a wide adsorption range of visible light, and a low recombination rate of carriers. With the help of carbon black, highly crystallized graphitic carbon nitrides with built-in triazine and heptazine heterojunctions are obtained. Improved photocatalytic activities have been achieved in carbon black-modified graphitic carbon nitride. The dye removal rate can be three times faster than that of pristine graphitic carbon nitride and the photocatalytic H2 generation is 234 μmol h?1 g?1 under visible light irradiation.
关键词： aqueous dyes removal,hydrogen production,carbon black doping,graphitic carbon nitride,visible-light photocatalytic activity
更新于2025-09-23 15:21:21
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Effective Photocatalytic Hydrogen Evolution by Cascadal Carrier Transfer in the Reverse Direction
摘要： Visible-light-responsive photocatalysts used in the highly efficient hydrogen production exhibit several disadvantages such as photocorrosion and fast recombination. Because of the potential important applications of such catalysts, it is crucial that a simple, effective solution is developed. In this respect, in this study, we combined SiC (β modification) and TiO2 with CdS to overcome the challenges of photocorrosion and fast recombination of CdS. Notably, we found that when irradiated with visible light, CdS was excited, and the excited electrons moved to the conduction band of TiO2, thereby increasing the efficiency of charge separation. In addition, by moving the holes generated on CdS to the valence band of SiC, in the opposite direction of TiO2, photocorrosion and fast recombination were prevented. As a result, in the sulfide solution, the CdS/SiC composite catalyst exhibited 4.3 times higher hydrogen generation ability than pure CdS. Moreover, this effect was enhanced with the addition of TiO2, giving 10.8 times higher hydrogen generation ability for the CdS/SiC/TiO2 catalyst. Notably, the most efficient catalyst, which was obtained by depositing Pt as a cocatalyst, exhibited 1.09 mmol g?1 h?1 hydrogen generation ability and an apparent quantum yield of 24.8%. Because water reduction proceeded on the TiO2 surface and oxidative sulfide decomposition proceeded on the SiC surface, the exposure of CdS to the solution was unnecessary, and X-ray photoelectron spectroscopy confirmed that photocorrosion was successfully suppressed. Thus, we believe that the effective composite photocatalyst construction method presented herein can also be applied to other visible-light-responsive powder photocatalysts having the same disadvantages as CdS, thereby improving the efficiency of such catalysts.
关键词： CdS,photocorrosion,hydrogen production,TiO2,photocatalysts,SiC,fast recombination
更新于2025-09-23 15:21:21
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Charge separation and electron transfer routes modulated with Co-Mo-P over g-C3N4 photocatalyst
摘要： In this case, a novel photocatalyst with visible light harvesting, spatial charge separation and effective electron transfer route is reported, which assemble Co-Mo-P nanoparticle on the surface of g-C3N4. The composite photocatalyst shows high H2 evolution with a yield of 646.4 μmol in 5 h, which is 66.7 times than over the pristine g-C3N4. The AQE measured was reached 5.25% at the wavelength of 475 nm after 1 h. The inner reason was comprehensively studied and understood by means of FESEM, HRTEM, XRD, XPS, UV–vis DRS and BET. Especially the investigation of their photoelectrochemical properties with photocurrent, voltammetric scanning, fluorescence spectra, etc. The characterization results show that CoMoP forms a large number of active sites on the surface of g-C3N4, which improves efficiency of the charge transfer and then accelerates the rate of HER. At the same time, the mechanism of H2 production of photocatalyst in the eosin Y sensitization system was proposed.
关键词： Hydrogen production,Electron transfer,Charge separation,Photocatalysis
更新于2025-09-23 15:21:01
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Nitrogen-doped Graphene Quantum Dots for Remarkable Solar Hydrogen Production
摘要： We synthesized nitrogen (N)-doped graphene quantum dots (N-GQDs) using a top-down hydrothermal cutting approach. The concentration of N dopants was readily controlled by adjusting the concentration of the N source of urea. When N dopants were incorporated into GQDs, visible absorption was induced by C-N bonds, which created another pathway for generating photoluminescence (PL). Time-resolved PL data revealed that the carrier lifetime of GQDs was increased upon doping with the optimized N concentration. The photoelectrochemical properties of N-GQDs towards water splitting were studied, and the results showed that 2N-GQDs prepared with 2 g of urea produced the highest photocurrent. The photocatalytic activity of 2N-GQDs powder photocatalyst for hydrogen production was also examined under AM 1.5G illumination, showing substantial enhancement over that of pristine GQDs. Electrochemical impedance spectroscopy data further revealed a significant improvement in charge dynamics and reaction kinetics, and an increased carrier concentration as a result of N doping.
关键词： Solar Hydrogen Production,Charge Dynamics,Water Splitting,Graphene Quantum Dots,Nitrogen-doped
更新于2025-09-23 15:21:01
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Novel parabolic trough solar collector and solar photovoltaic/thermal hybrid system for multi-generational systems
摘要： A novel hybrid system, comprising a parabolic trough solar collector and solar photovoltaic/thermal collector units, is proposed and structured for useful multi-generational purposes with hydrogen production. The designed system comprises a parabolic trough solar collector for electricity generation, hydrogen production, and cooling applications. The solar photovoltaic/thermal collector modules serve the purposes of hydrogen production and space heating. A thermodynamic analysis was conducted for practical applications and implementation. The overall energy and exergy efficiencies of the system were calculated to be 12.90% and 54.72%, respectively, for a solar fluid exit temperature of 477 K. The hydrogen production could reach up to 8.226 g/s from the parabolic trough solar collector electrolyzer and 0.07518 g/s from the solar photovoltaic/thermal collector electrolyzer, which could be used for various useful domestic, medical, and industrial applications. The effects of varying the solar fluid exit temperature, incident solar irradiation, ambient temperature, and working fluids on the working system capability were examined. The proposed system demonstrated that the standalone solar hybrid system could serve as a vital tool for essential energy output purposes that are physically practical and economically viable.
关键词： Heating,Solar energy,Power generation,Hydrogen production,Exergy,Efficiency,Cooling
更新于2025-09-23 15:21:01
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Highly efficient white-LED-light-driven photocatalytic hydrogen production using highly crystalline ZnFe2O4/MoS2 nanocomposites
摘要： Designing efficient photocatalytic systems for hydrogen evolution is extremely important from the viewpoint of the energy crisis. Highly crystalline heterostructure catalysts have been established, considering their interface electric field effect and structural features, which can help improve their photocatalytic hydrogen-production activity. In this study, we fabricated a highly crystalline heterojunction consisting of ZnFe2O4 nanobricks anchored onto 2D molybdenum disulfide (MoS2) nanosheets (i.e., ZnFe2O4/MoS2) via a hydrothermal approach. The optimized ZnFe2O4/MoS2 photocatalyst, with a ZnFe2O4 content of 7.5 wt%, exhibited a high hydrogen-production rate of 142.1 mmol h?1 g?1, which was 10.3 times greater than that for the pristine ZnFe2O4 under identical conditions. The photoelectrochemical results revealed that the ZnFe2O4/MoS2 heterojunction considerably diminished the recombination of electrons and holes and promoted efficient charge transfer. Subsequently, the plausible Z-scheme mechanism for photocatalytic hydrogen production under white-LED light irradiation was discussed. Additionally, the influence of cocatalysts on the photocatalytic hydrogen evolution for the ZnFe2O4/MoS2 heterostructure was investigated. This work has demonstrated a simplified coupling of one-dimensional or zero-dimensional structures with 2D nanosheets for improving the photocatalytic hydrogen production activity as well as confirmed that MoS2 is a viable substitute for precious metal-free photocatalysis.
关键词： Photocatalytic hydrogen production,Layered materials,MoS2,Photocatalysts,Heterojunction
更新于2025-09-23 15:21:01
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Data on combination of parabolic solar system with CH4 cycle and power tower solar system with Cu–Cl cycle for hydrogen production in the city of Ghardaia (Algeria)
摘要： This data show the combination of parabolic through solar system with CH4 cycle and power tower solar system with Cu–Cl cycle for hydrogen production capacity in the city of Gharadaia which is located in the south of Algeria. A proper measurement of meteorological factors such as temperature, humidity, and solar irradiation has been done in the city of Ghardaia due to the solar concentration in this city. In the meantime thermo-chemical systems (Cu–Cl, CH4 cycles) have been integrated with the thermal solar systems through.
关键词： Solar energy,Hydrogen production
更新于2025-09-23 15:21:01
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Facile preparation of self-assembled MXene@Au@CdS nanocomposite with enhanced photocatalytic hydrogen production activity; è?a???è￡??o3?±3?¤??????????MXene@Au@CdS???????¤????????????????????°￠?′???§;
摘要： Photocatalytic hydrogen production is considered a promising approach to generating clean sustainable energy. However, the conventional co-catalyst (e.g., Pt) used in photocatalytic hydrogen production is high-cost and difficult to obtain. Here, we designed and prepared a ternary nanocomposite MXene@Au@CdS, which can be used in the field of efficient and excellent photocatalytic hydrogen production. The MXene@Au@CdS has a hydrogen production rate of 17,070.43 μmol g?1 h?1 (tested for 2 h), which is 1.85 times that of pure CdS nanomaterials. The improved hydrogen production performance of the MXene@Au@CdS is attributed to: (i) MXene provides more active adsorption sites and reaction centers for Au and CdS nanoparticles; (ii) the synergistic effect of Au’s strong surface plasmon resonance expands the optical response range of CdS. Therefore, this work solves the problem of the solid connection between the surface functional groups of photocatalyst, and achieves rapid interface charge transfer and long-term stability during the hydrogen production.
关键词： MXene,nanocomposite,photocatalytic hydrogen production
更新于2025-09-23 15:21:01