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Pyrolysis‐Synthesized g‐C <sub/>3</sub> N <sub/>4</sub> /Nb <sub/>2</sub> O <sub/>5</sub> Nanocomposite for Enhanced Photocatalytic Activity under White LED Light Irradiation
摘要： The design and fabrication of highly active visible-light-driven photocatalysts have been received considerable attention in recent years. However, individual component-based photocatalysts are limited in their use because of the high recombination of photoinduced carriers and poor chemical stability. Herein, the Z-scheme-originated photocatalytic activity of in-situ deposited Nb2O5 NPs on the plane surface of carbon nitride (g-C3N4) nanosheets (i. e. CN-NbO) heterostructures was studied using a simple thermal pyrolysis method. The as-synthesized photocatalysts distinctly manifested efficient white light-emitting diode (LED) irradiation toward organic malachite green (MG) dye degradation and photocatalytic hydrogen generation. The CN-NbO heterostructure showed a faster degradation rate of the MG dye and a higher photocatalytic hydrogen evolution rate. In addition, the plausible Z-scheme photocatalytic mechanism for photocatalytic hydrogen production under LED light irradiation was discussed. Photoelectrochemcial studies showed that the superior photoactivity of CN-NbO heterostructure is mainly a result of the suitable alignment of the band edge positions, which diminish carrier recombination and facilitate efficient interfacial charge transport at their interface. This study provides an ideal method for in-situ fabrication of novel two dimensional/one dimension-based photocatalysts with high activity and stable performance for photocatalytic hydrogen generation.
关键词： Dye degradation,Hydrogen evolution,Nanoparticles,Photocatalyst,LED irradiation,Layered materials
更新于2025-09-11 14:15:04
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Triple-Shelled Co-VSex Hollow Nanocages as Superior Bifunctional Electrode Materials for Efficient Pt-Free Dye-Sensitized Solar Cells and Hydrogen Evolution Reactions
摘要： Complex nanostructures with distinct spatial architectures and more active sites hold broad prospects in new energy conversion fields. Herein, a facile strategy was carried out to construct triple-shelled Co-VSex nanocages, starting via an ion-exchange process about Co-based zeolitic imidazolate framework-67 (ZIF-67) nanopolyhedrons and VO3?, followed by the formation of triple-shelled Co-VSex hollow nanocages during the process of rising the solvothermal temperature under the assistance of SeO32?. Meanwhile, triple-shelled Co-VSx and yolk-double shell Co-VOx nanocages were fabricated as references by a similar process. Benefiting from the larger surface areas and more electrolyte adsorption sites, the triple-shelled Co-VSex nanocages exhibited excellent electrocatalytic performances when applied as the electrochemical catalysts for dye-sensitized solar cell (DSSC) and hydrogen evolution reaction (HER). More concretely, the DSSC based on Co-VSex counter electrode (CE) showed outstanding power conversion efficiency of 9.68% when Pt counterpart was 8.46%. Moreover, Co-VSex electrocatalyst exhibited prominent HER performance with a low onset overpotential of 40 mV and a small Tafel slope of 39.1 mV dec?1 in acid solution.
关键词： Dye-sensitized solar cells,Hydrogen evolution reactions,Pt-free catalysts,Triple-shelled nanocages,Co-VSex,Bifunctional electrocatalysts
更新于2025-09-11 14:15:04
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Fabricating Cu, Cu<sub>2</sub>O and Hybrid Cu-Cu<sub>2</sub>O nanoparticles in carbon matrix and exploring catalytic activity of oxygen and hydrogen evolution and green A<sup>3</sup>-coupling reaction
摘要： Hybrid Cu-Cu2O as well as Cu and Cu2O@C nanoparticles (NPs) encapsulated by carbon matrix have been synthesized and bifunctional electrocatalytic activity (OER and HER) and A3 coupling (three components reaction) were explored. Powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and high resolution transmission electron microscopy (HR-TEM) studies were performed to analyse structure, chemical state, and size of the nanocatalysts. Hybrid Cu-Cu2O@C materials exhibited stronger electrocatalytic activity compared to pure phases whereas pure Cu and Cu2O@C NPs displayed better catalytic activity for A3 coupling reaction. Oxygen and hydrogen evolution reaction (OER and HER) showed enhanced current response (57.8 mA/cm2 and -172 mA/cm2) for hybrid NPs with higher Cu2O ratio. Thus, the present work investigated the role of Cu and Cu2O ratio for fabricating earth abundant cost effective nanocatalysts for OER, HER, and organic chemical transformation.
关键词： Water splitting,A3 coupling,Oxygen evolution reaction,Hydrogen evolution reaction,Cu-Cu2O nanoparticles,Electrocatalyst
更新于2025-09-10 09:29:36
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Effect of Linking Pattern of Dibenzothiophene- <i>S</i> , <i>S</i> -dioxide-Containing Conjugated Microporous Polymers on the Photocatalytic Performance
摘要： Conjugated microporous polymers (CMPs) exhibit great potential for photocatalytic hydrogen generation due to their tunable electronic structure. The rational molecular design is a key point for developing an efficient CMP photocatalyst. Herein, we developed two CMPs photocatalysts via the copolymerization from pyrene and dibenzothiophene-S,S-dioxide building blocks. The effect of the linking pattern of the building block of dibenzothiophene-S,S-dioxide on the photocatalytic hydrogen evolution was explored. The polymer of PyDOBT-1 with 3,7-linking pattern shows a superior photocatalytic performance to PyDOBT-2 with 2,8-linking pattern because the 3,7-linking pattern enhances the conjugation chain length and improves the coplanarity of the polymeric backbone, which facilitate the charges migration along the polymer chain. As a result, the bare PyDOBT-1 shows an impressive visible light activity with a hydrogen evolution rate (HER) of 5697 μmol h?1 g?1. Notably, an outstanding HER of 12986 μmol h?1 g?1 was also obtained by the Pt-modified PyDOBT-1 under the full-arc spectrum (λ > 300 nm), which lies toward the upper end compared to that of the reported organic photocatalysts.
关键词： Conjugated microporous polymers,Dibenzothiophene-S,S-dioxide,Photocatalytic hydrogen generation,Linking pattern,Hydrogen evolution rate
更新于2025-09-10 09:29:36
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Direct Z-scheme 2D/2D MnIn2S4/g-C3N4 architectures with highly efficient photocatalytic activities towards treatment of pharmaceutical wastewater and hydrogen evolution
摘要： Semiconductor photocatalysis has been regarded as an environmentally friendly technology in wastewater treatment and energy production. Here, a series of direct Z-scheme MnIn2S4/g-C3N4 (MnISCN) photocatalysts without electron mediators were fabricated by a simple hydrothermal route on the basis of in-situ loading of MnIn2S4 (MnIS) nanoflakes on the surface of g-C3N4 (CN) nanosheets. Photocatalytic performances evaluated under visible light irradiation revealed these Z-scheme heterostructured photocatalysts exhibited higher photocatalytic activities than single-component samples. The effect of weight ratio between MnIn2S4 nanoflakes and mesoporous CN nanosheets on photocatalytic activity towards treatment of pharmaceutical wastewater was optimized to achieve highly efficient photocatalytic activities for both degradation of pharmaceutical wastewater and hydrogen generation compared with alone MnIS nanoflakes and isolated mesoporous CN nanosheets. The significant enhancement in photocatalytic activity could be primarily ascribed to the construction of Z-scheme MnISCN architectures, which effectively accelerated the transfer and separation of photogenerated charge carriers via tight interface contacts built among these two components. The recycling experiments for pharmaceutical wastewater treatment revealed the excellent stability of MnISCN nanocomposites. The advantages of highly efficient photocatalytic activity and excellent stability endowed a promising potential for MnISCN nanocomposites to apply in photocatalytic fields.
关键词： pharmaceutical wastewater,g-C3N4,hydrogen evolution,Z-scheme,MnIn2S4
更新于2025-09-10 09:29:36
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Enhanced Electron Separation on in-Plane Benzene-Ring Doped g-C3N4 Nanosheets for Visible Light Photocatalytic Hydrogen Evolution
摘要： Solar-to-chemical energy conversion by photocatalytic hydrogen evolution (PHE) is critical for reduction of the pollution and storage of clean energy. To improve the solar conversion efficiency, it is highly imperative to accelerate the photocarrier separation and transportation through materials design. Herein, we describe a highly effective PHE catalyst based on in-plane benzene-ring doped g-C3N4 nanosheets heterostructure through the thermal co-polymerization of urea and 4, 4'-sulfonyldiphenol (BPS) followed by a controlled heat-etching step. The solid-state 13C NMR confirms the existence of benzene-ring structure in g-C3N4 nanosheets. Experimental results and theoretical calculations show that the energy and electronic structure of the catalyst are optimally regulated, inducing increased light absorption and effectively accelerated separation of the photo-driven charge carriers. It exhibits enhanced photocatalytic hydrogen evolution efficiency with a PHE rate of 12.3 mmol h-1 g-1 (almost 12 times higher than that of pure g-C3N4 nanosheets) and the quantum efficiency of 17.7 % at 420 nm.
关键词： g-C3N4,hydrogen evolution,in-plane,benzene-ring doping,photocatalysis
更新于2025-09-10 09:29:36
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Comparative activity of aqueous dispersions of CdS nanocrystals stabilized by cationic and anionic polyelectrolytes in photocatalytic hydrogen production from water
摘要： The results of a study on the photocatalytic activity of aqueous dispersions of Ni-doped CdS nanocrystals (NCs) covered with an amphiphilic polyelectrolyte (PE) shell, i.e., a polycation (NC-PC) or polyanion (NC-PA), are presented for the first time. The H2 evolution rate measured under identical conditions served as a measure of activity. The NC-PC and NC-PA samples were characterized by similar PE content (~40%) and monomodal size distribution. According to our calculations based on the NC dimensions and lattice parameters, about one macromolecule of the PE is required to stabilize one NC. The average hydrodynamic diameter of the NC-PC was found to be 1.5 times larger than that of the NC-PA due to the difference between their chemical structures and different abilities of ionogenic groups to dissociate. The photocatalytic activity of the PE-stabilized CdS nanocrystals was significantly influenced by the type of the PE, while the H2 evolution rate depended on the reducing medium used during the process. When the medium contained Na2S or when the PE-stabilized NCs were pre-treated with Na2S, the effect of the shell type was more pronounced and the activity of NC-PA was 2 to 14 times higher than that of NC-PC.
关键词： polyelectrolytes,nanocrystals,photocatalysis,cadmium sulfide,hydrogen evolution reactions,nickel
更新于2025-09-10 09:29:36
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Self-constructed facet junctions on hexagonal CdS single crystals with high photoactivity and photostability for water splitting
摘要： Crystal facets engineering of semiconductor catalysts with different exposed facets has been proven as a versatile approach to enhance their photocatalytic performance. Herein, for the first time, a facet-junction engineered hexagonal CdS single crystal with exposing {0001} and {10 0} facets was synthesized by hydrothermal reaction via adjusting the molar ratio of S2-/Cd2+ precursor. The co-exposed {0001} and {10 0} facets on hexagonal CdS single crystals with continuous band bending and well-defined epitaxial interfaces showed highly efficient visible-light-induced H2 evolution. The maximum photocatalytic H2 production rate of 24.33 mmol h?1g?1 is obtained over the facet-junction engineered hexagonal CdS-5 single crystals with an apparent quantum efficiency of 11.18% at 470 nm, which is about 5.27 times greater than CdS-1 nanoparticles. Also, superior photostability is also achieved, even after 25 consecutive cycles during 100 h light irradiation keeping impregnated in strong alkaline sacrificial agent beyond 20 days, the initial photoactivity is still remained. The enhanced photocatalytic H2 evolution activity and photostability can be ascribed to the type-II band alignment between the co-exposed {0001} and {10 0} facets that significantly promoted the separation rate of photo-generated electrons and holes. And the small amount of sulfur vacancies are also benefit for the photocatalytic hydrogen evolution activity of CdS-5. The time-resolved fluorescence (TRPL) decay and photoelectrochemical test further proved the effective spatial charge separation. This work provides a feasible and simple strategy for designing of facet-junction engineered CdS single crystals with highly efficient photocatalytic activity and unprecedented photostability.
关键词： hexagonal CdS single crystals,{0001} facets,photocatalytic hydrogen evolution,facet junction
更新于2025-09-10 09:29:36
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Au decorated hollow ZnO@ZnS heterostructure for enhanced photocatalytic hydrogen evolution: The insight into the roles of hollow channel and Au nanoparticles
摘要： A new type of Au nanoparticles (NPs) decorated hollow flower-like ZnO@ZnS (HZOS) heterostructure (HS) is elaborately designed as efficient photocatalyst for water splitting application. The optimal Au decorated HZOS exhibits a high hydrogen generation rate of 569.81 μmol/h (10 mg of catalyst), which is 345, 374 and 11 times higher than that of pristine ZnO (1.65 μmol/h), ZnS (1.52 μmol/h) and ZnO@ZnS (51.7 μmol/h), respectively. Furthermore, its apparent quantum efficiency reaches to 25.47 % at the wavelength of 365 nm. The significantly enhanced H2 evolution can be attributed to the synergistic effects from the hollow channel structure and the deposited Au NPs. The hollow channel creates a new migration pathway where charge carriers can transfer towards the hollow channel in addition to the outer surface of the photocatalyst, thus significantly reducing the migration distance of charge carriers, suppressing the recombination of photogenerated electrons and holes, and reducing their transfer resistance. The decoration of Au NPs at the interface between ZnO and ZnS not only facilitates the directional migration of charge carriers because of the formation of Schottky barrier, but also works as electron shuttles to form a Z-scheme transfer process, effectively promoting the separation and migration of charge carriers.
关键词： photocatalysis,heterostructure,hydrogen evolution,Z-scheme,hollow channel
更新于2025-09-10 09:29:36
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Low-Temperature Wafer-Scale Growth of MoS2-Graphene Heterostructures
摘要： In this study, we successfully demonstrate the fabrication of a MoS2-graphene heterostructure (MGH) on a 4-inch wafer at 300 oC by depositing a thin Mo film seed layer on graphene followed by sulfurization using H2S plasma. By utilizing Raman spectroscopy and high-resolution transmission electron microscopy, we have confirmed that 5–6 MoS2 layers with a large density of sulfur vacancies are grown uniformly on the entire substrate. The chemical composition of MoS2 on graphene was evaluated by X-ray photoelectron spectroscopy, which confirmed the atomic ratio of Mo to S to be 1:1.78, which is much lower than the stoichiometric value of 2 from standard MoS2. To exploit the properties of the nanocrystalline and defective MGH film obtained in our process, we have utilized it as a catalyst for hydrodesulfurization and as an electrocatalyst for the hydrogen evolution reaction. Compared to MoS2 grown on an amorphous SiO2 substrate, the MGH has smaller onset potential and Tafel slope, indicating its enhanced catalytic performance. Our practical growth approach can be applied to other two-dimensional crystals, which are potentially used in a wide range of applications such as electronic devices and catalysis.
关键词： PECVD,graphene,large-scale,heterostructure,hydrogen evolution reaction,MoS2
更新于2025-09-10 09:29:36