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Tunable Type I and II heterojunction of CoOx nanoparticles confined in g-C3N4 nanotubes for photocatalytic hydrogen production
摘要： This work reports tunable heterojunction architectures of cobalt oxides (CoOx) nanoparticles confined on well-arrayed graphitic carbon nitride nanotubes (C3N4 NTs) by using a facile one-pot method but under different annealing atmospheres. A Type II heterojunction of cobalt monoxide nanoparticles (CoO NPs)/C3N4 NTs was obtained after annealing under vacuum, and fine CoO NPs less than 8 nm in size were homogeneously anchored on the surface of C3N4 NTs. A Type I heterojunction of tricobalt tetraoxide (Co3O4)/C3N4 NTs were formed under air condition, and Co3O4 NPs in the size range of 20 to 80 nm were aggregated on the surface. The photocatalytic activities of these two heterojunctions were evaluated with hydrogen production from water splitting. The strategically developed CoO/C3N4 NTs with a 7 wt. % CoO shows the highest H2 yield under visible light irradiation and the best stability among the photocatalysts studied in this work. Comprehensive characterization results reveal that the superior performance of CoO/C3N4 NTs may be attributed to the uniformly distributed smaller nanoparticles on the well-arrayed nanotubes, the longer lifetime of excited electrons, the faster charge transfer and the stronger electronic interaction between the heterojunctions. Our Kelvin probe force microscopy results firmly verify that the CoO/C3N4 NT and Co3O4/C3N4 NT nanocomposites form a Type II and Type I heterojunction, respectively, and charge transfer pathways and reaction mechanisms are therefore established.
关键词： hydrogen production,carbon nitride nanotubes,tricobalt tetraoxide,Heterojunction architectures,cobalt monoxide
更新于2025-09-10 09:29:36
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Photocatalytic decomposition of methanol-water solution over N-La/TiO2 photocatalysts
摘要： Manuscript focuses on the role of N-doping on photocatalytic behaviour of N-La/TiO2 materials in decomposition of methanol-water solution. N-La/TiO2 materials were prepared with approximately the same amounts of La (0.14–0.16 wt%) and di?erent amounts of N (0.33–0.97 at. % of surface nitrogen). Addition of small amount of surface nitrogen signi?cantly increased the amount of hydrogen produced for N-La/TiO2 photocatalysts in contrast to TiO2 and La/TiO2. The chemical composition (XRF, AAS, XPS), structural (XRD, Raman, XPS, TEM), textural (N2-adsorption) and optical properties (DRS) were studied. N-La/TiO2 materials showed approximately the same speci?c surface area and crystallite size, with values ranging for La/TiO2 and N/TiO2 photocatalysts. For studied N-La/TiO2 photocatalysts, the photocatalytic activity increased with the increasing amount of surface nitrogen (interstitial positions, XPS), and subsequently with increasing amount of oxygen vacancies (Raman spectroscopy) and decreasing amount of surface oxygen species (surface lattice O species and hydroxyl groups evidenced by XPS).
关键词： Surface oxygen species,N-La/TiO2,Oxygen vacancies,Hydrogen production
更新于2025-09-10 09:29:36
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Heteroleptic copper(I) photosensitizers with carbazole-substituted phenanthroline ligands: Synthesis, photophysical properties and application to photocatalytic H2 generation
摘要： A series of novel 4,7-dicarbazol-1,10-phenanthroline bidentate N-ligands have been designed and synthesized, and applied in heteroleptic copper complexes [Cu(P?P)(N?N)]+ as photosensitizers (PS) for light-driven water reduction. In combination with a water reduction catalyst (WRC), Fe3CO12, photocatalytic performances up to 1036 turnover numbers (TON) were reached. This excellent performance can be attributed to the introduction of carbazole groups to the phenanthroline backbone, which can increase the ?uorescence quantum yield, decrease the reduction potential of the copper complexes and switch the excited state quenching mechanism from reductive to oxidative. By means of DFT calculations, it has been established that the carbazole substituent contributes most signi?cantly to the HOMO of these complexes.
关键词： Hydrogen production,Photosensitizers,Water reduction
更新于2025-09-10 09:29:36
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Role of phosphate in ruthenium-complex-sensitized TiO2 system for hydrogen production: mechanism and kinetics
摘要： Most Ru(II) complex-sensitized TiO2 systems for hydrogen (H2) production suffer from instability of the photosensitized system because the anchoring groups of Ru(II) dyes, which are required for their adsorption on TiO2, are intrinsically vulnerable to chemical and photochemical cleavage. In this study, a new method that enables the use of a Ru(II) dye without any anchoring groups (Ru(bpy)3 2+) was developed and investigated. The stable photocatalytic efficiency in repeated H2 production cycles under visible-light irradiation indicates that the Ru(II) dye without anchoring groups is highly stable during dye-sensitized H2 production. The dye-sensitized H2 production in the Ru(bpy)3 2+-sensitized TiO2 system comprising Ru(bpy)3 2+ as a photosensitizer, platinized TiO2 (Pt-TiO2) as a cocatalyst-electron mediator, and ethylenediaminetetraacetic acid as an electron donor was negligible. However, the addition of phosphate (PO4 3–) to the Ru(bpy)3 2+-sensitized TiO2 system enabled the production of H2 via dye sensitization in the absence of any anchoring groups on the dye. The adsorption of PO4 3– changed the surface charge of Pt-TiO2 from positive to negative under acidic conditions, thereby inducing adsorption of cationic Ru(bpy)3 2+ on the surface of Pt-TiO2 and facilitating electron transfer from excited Ru(bpy)3 2+ to the conduction band of TiO2. The PO4 3– adsorption-induced change in the surface charge and the subsequent adsorption of Ru(bpy)3 2+ on the surface of PO4 3–-adsorbed Pt-TiO2 were confirmed by zeta potential measurements and Fourier transform infrared spectroscopy, respectively. In contrast with H2 production, the presence of PO4 3– had little effect on the kinetics of anionic chromate (CrO4 2–) reduction in the Ru(bpy)3 2+-sensitized TiO2 system. This result indicates that electron transfer from Pt to the electron acceptor on PO4 3–-adsorbed Pt-TiO2 is highly dependent on the charge character of the electron acceptor (i.e., electron transfer to the cationic electron acceptor is more favored). The negative charge on the surface of Pt-TiO2 induced by the adsorption of PO4 3– attracts the positively charged protons to the surface, which kinetically enhanced electron transfer from Pt to the protons. The (photo)electrochemical data demonstrate that PO4 3– adsorbed on Pt-TiO2 facilitates the interfacial electron transfer processes by enhancing the adsorption of Ru(bpy)3 2+ and attracting protons to the surface. The positive effect of PO4 3– on H2 production increased with increasing PO4 3– concentration and decreasing pH, where the conditions are more favorable for PO4 3– and proton adsorption on the surface of Pt-TiO2. Among the five anions evaluated in this study (PO4 3–, AsO4 3–, F–, NO3 –, and SO4 2–), PO4 3– was most efficient and facilitated stable H2 production.
关键词： Phosphate,Dye sensitization,Hydrogen production,Photocatalysis,Ruthenium-complex
更新于2025-09-10 09:29:36
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Toward Concurrent Organics Removal and Potential Hydrogen Production in Wastewater Treatment: Photoelectrochemical Decolorization of Methylene Blue over Hematite Electrode in the Presence of Mn(II)
摘要： A sustainable system capable of simultaneous removal of organic contaminants and hydrogen generation in wastewater treatment operation was studied using hematite electrode in the presence of Mn(II), PEC-Mn(II), as a proof of concept. The photoelectrochemical (PEC) system exhibited methylene blue (MB) decolorization threefold faster than that of photo-Fenton processes and yielded comparable photocurrent density to relative to the control system, i.e., PEC water splitting in the absence of MB at otherwise identical operation conditions. Furthermore, the advantages of PEC-Mn(II) system were no H2O2 addition, hydrogen production potential, and ease in Mn(II) separation via the formation of MnO2 precipitates during wastewater treatment operations. The PEC-Mn(II) process is a promising and sustainable approach toward wastewater treatment with the capability of concurrent photochemical energy generation. Moreover, the PEC-Mn(II) process can be an emerging energy-from-wastewater alternative in addition to other systems such as microbial fuel cell and anaerobic digestion.
关键词： Wastewater Treatment,Decolorization,Sustainability,Photoelectrochemical,Hydrogen production
更新于2025-09-10 09:29:36
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Layered lithium niobium (III) oxide—LiNbO <sub/>2</sub> as a visible-light-driven photocatalyst for H <sub/>2</sub> evolution
摘要： The search for visible-light photocatalysts is of great significance in clean energy and environmental applications to best utilize solar radiation. Some layered semiconductor photocatalysts have been found to exhibit promising performance levels. Their superior activity has been linked to the layering within the crystal structure, which may facilitate separation of carriers and, hence the reduction and oxidation reactions. Previous investigations on layered materials focused on oxides containing early transition metal cations with d0 electronic configurations utilizing ultraviolet radiation. Attempts to synthesize layered materials with visible light response have been less successful and the photoactivity of such materials is not very high. Here, we have investigated a layered semiconducting compound, LiNbO2 with nominal d2 electronic configuration (Nb3+). As a result of a sub-valence band originating from filled d orbitals, LiNbO2 exhibits visible light absorption extending to 650 nm and demonstrates interesting photocatalytic activity for hydrogen production.
关键词： clean energy,photocatalysts,layered semi conducting compound,hydrogen production
更新于2025-09-10 09:29:36
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Improved Microbial Electrolysis Cell Hydrogen Production by Hybridization with a TiO2 Nanotube Array Photoanode
摘要： A microbial electrolysis cell (MEC) consumes the chemical energy of organic material producing, in turn, hydrogen. This study presents a new hybrid MEC design with improved performance. An external TiO2 nanotube (TNT) array photoanode, fabricated by anodization of Ti foil, supplies photogenerated electrons to the MEC electrical circuit, signi?cantly improving overall performance. The photogenerated electrons help to reduce electron depletion of the bioanode, and improve the proton reduction reaction at the cathode. Under simulated AM 1.5 illumination (100 mW cm?2) the 28 mL hybrid MEC exhibits a H2 evolution rate of 1434.268 ± 114.174 mmol m?3 h?1, a current density of 0.371 ± 0.000 mA cm?2 and power density of 1415.311 ± 23.937 mW m?2, that are respectively 30.76%, 34.4%, and 26.0% higher than a MEC under dark condition.
关键词： hydrogen production,microbial electrolysis cell,TiO2 nanotube
更新于2025-09-09 09:28:46
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Green Energy based Thermochemical and Photochemical Hydrogen Production
摘要： A significant amount of hydrogen is required to satisfy the hydroprocessing needs of petroleum refinery, natural gas cleaning, and biofuel upgrading. Meanwhile, hydrogen is a very promising candidate of energy due to its high energy output per mass unit as compared to other sources of energy. In this article, the production of hydrogen is overviewed from the traditional technology as the thermochemical processes of fossil fuels to the current development in photoelectrochemical processes or even hybrid technologies. The catalysts for methane reforming and visible-light absorption were summarized. Both processes employ oxides as the catalyst. Because catalytic oxides are mostly lack of visible-light absorption function, the visible-light absorption properties could be rendered by doping these oxides with metal, nitrogen, or even sulfur. Further complete substitution of the oxygen atoms leads to non-oxide catalyst. Moreover, multidimensional photochemical catalysts have acquired more attention over traditional powered catalysts. Finally, a vision is exhibited for the efficiency and the future trends on production of H2.
关键词： Tri-reforming,catalyst,Biomass,Electrolysis,Dry Reforming,Hydrogen Production,Steam Reforming,Methane,Autothermal Reforming,Solar energy,Gasification,Coal
更新于2025-09-09 09:28:46
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Comparative Study on The Photocatalytic Hydrogen Production from Methanol over Cu-, Pd-, Co- and Au-Loaded TiO <sub/>2</sub>
摘要： Photocatalytic hydrogen production from a methanol-water solution was investigated in a semi-continuous reactor over different metal-loaded TiO2 catalysts under UltraViolet (UV) light irradiation. The catalysts were mainly prepared by the incipient wetness impregnation method by varying the metal weight ratio in the range of 1-10 wt%. The effects of metal loading and H2 pre-treatment on the photocatalytic activity were investigated. In addition, the activity of the catalysts was also compared with a reference Au-TiO2 catalyst from the World Gold Council (WGC). The photocatalysts were characterized by using X-Ray Diffraction (XRD) and N2 physisorption before and after the activity measurements. The photocatalytic activity decreased in the order of Pd > Au > Cu > Co in the comparative study of Cu-TiO2, Co-TiO2, Au-TiO2 and Pd-TiO2. Optimum hydrogen evolution was achieved with 5 wt% Pd-TiO2 and 5 wt% Cu-TiO2.
关键词： Metal loading,UV light irradiation,Photocatalytic hydrogen production,Methanol,TiO2
更新于2025-09-09 09:28:46
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Nanoscale Materials in Water Purification || Photocatalysis of Graphene and Carbon Nitride-Based Functional Carbon Quantum Dots
摘要： Day by day, global energy demands increase due to the rapid consumption of depleting fossil fuels and environmental pollution. This has led to the search for materials capable of both energy conversion and elimination of environmental pollutants through the aid of renewable solar energy. This is a promising approach for meeting future energy requirements and eliminating environmental pollutants. In this pursuit, semiconductor photocatalysts have immense potential for solving both energy and environmental issues. To date, numerous semiconductor materials have been explored, including those of metal oxides, chalcogenides, borates, titanates, tungstates, vanadates, zirconates, oxyhalides, and metal-based interstitial compounds. However, the majority of these suffer from limitations such as complex synthesis procedures, limited light absorption range due to their wide band gap, high cost, and toxicity-related issues. Over the past decade, carbon-based nanomaterials have gained attention in the field of photocatalysis. Many recent articles have placed emphasis upon metal-free carbon-based photocatalytic systems for degradation of organic pollutants and hydrogen production from water splitting. The prime merit of these nanomaterials is that they originate from naturally abundant constituent elements such as carbon, nitrogen, and oxygen, making them more economical than their metal-based counterparts. Most reported carbon-based photocatalysts have tunable band gap energies, enhancing their optical absorption range. Band gap energy can be tuned by varying synthesis conditions and precursors, resulting in the formation of nanomaterials with different morphologies. The preparation procedures for most carbon-based nanomaterials are less complex than those of metal-based materials.
关键词： water splitting,energy conversion,semiconductor photocatalysts,graphene,carbon nitride,quantum dots,carbon-based nanomaterials,hydrogen production,solar energy,environmental pollutants,photocatalysis
更新于2025-09-09 09:28:46