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Defective ZnS nanoparticles anchored in situ on N-doped carbon as a superior oxygen reduction reaction catalyst
摘要： Defect engineering has been used to develop low-cost and effective catalysts to boost oxygen reduction reactions. However, the development of catalysts that use metal cation vacancies as the active sites for oxygen reduction reaction is lacking. In this study, ZnS nanoparticles on N-doped carbon serve as an oxygen reduction reaction catalyst. These catalysts were prepared via a one-step method at 900 °C. Amazingly, the high-resolution transmission electron microscope image revealed obvious defects in the ZnS nanoparticles. These facilitated the catalyst synthesis, and the product displayed good electrocatalytic performance for the oxygen reduction reaction in an alkaline medium, including a lower onset potential, lower mid-wave potential, four electron transfer process, and better durability compared with 20 wt% Pt/C. More importantly, the density functional theory results indicated that using the Zn vacancies in the prepared catalyst as active sites required a lower reaction energy to produce OOH ? from ?OO toward oxygen reduction reaction. Therefore, the proposed catalyst with Zn vacancies can be used as a potential electrocatalyst and may be substitutes for Pt-based catalysts in fuel cells, given the novel catalyst’s resulting performance.
关键词： Density functional theory calculations,Oxygen reduction reaction,Zn vacancy,Electrocatalyst,Defective ZnS nanoparticle
更新于2025-11-14 17:03:37
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Ultrasound-Assisted Nitrogen and Boron Co-doping of Graphene Oxide for Efficient Oxygen Reduction Reaction
摘要： Development of naturally abundant, low cost, and energy-efficient electrocatalysts for the oxygen reduction reaction (ORR) is essential for commercialization of fuel cells. In this work, we report simple ultrasonication assisted synthesis of nitrogen and boron dual-doped graphene oxide (NB/GO) and demonstrate its application as an effective ORR catalyst realizing predominantly 4e? reduction of O2 to OH? in 0.1 M KOH. Enhanced ORR electrocatalysis of the dual B and N co-doped GO as opposed to GO singly doped with B or N arises from the synergistic interaction of the boron and nitrogen species. The content and configuration of both N and B dopants can be readily tailored by controlling the ultrasonic conditions, thereby permitting tuning of the ORR activity. Furthermore, the developed NB/GO metal-free catalyst exhibited very promising long-term durability and resistance to methanol poisoning compared to the state of the art Pt/C catalyst.
关键词： Oxygen reduction reaction,Graphene,Doping,Electrocatalysis
更新于2025-09-23 15:23:52
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Fe-N3/C active catalytic sites for the oxygen reduction reaction prepared with molecular level geometry control via covalent immobilization of iron-terpyridine motif onto carbon
摘要： A model for a non-precious metal catalyst for the oxygen reduction reaction (ORR) in aqueous media has been prepared by functionalizing a commercial Vulcan XC-72 carbon support with a terpyridine-based nitrogenous ligand. The terpyridine ligand geometry allows the formation of active catalytic sites by selectively embedding an N3/C structural motif into the carbon support confirmed by thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) measurements. Room temperature metal-ligand coordination results in desired Fe-N3/C moieties on the surface. This model system was used to demonstrate catalytic activity of the surfaces containing mainly Fe-N3 sites for ORR in acidic and basic media. Importantly, we demonstrate that the system could be prepared at mild reaction conditions, does not require high-temperature treatments, and shows catalytic activity for ORR. Interestingly, when the system was pyrolyzed in an N2 atmosphere at 700?C, the resulting activity declined. The non-heat-treated Fe-N3/C surface demonstrates comparable activity in acidic electrolyte medium when compared to most literature catalysts that are typically heat treated to produce four nitrogen’s coordinated to one iron center (Fe-N2+2/C). Interestingly, despite the fact that many systems reported so far in the literature exhibit enhanced activity after heat treatment, our system showed an increase in activity when the material was not pyrolyzed.
关键词： catalyst,oxygen reduction reaction,nitrogen,iron,non-precious metal
更新于2025-09-23 15:22:29
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Pulsed laser deposition of BaCo0.4Fe0.4Zr0.1Y0.1O3-δ cathode for solid oxide fuel cells
摘要： We herein report a thin film deposition of perovskite BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) by pulsed laser depositing (PLD) method for the use as a cathode in solid oxide fuel cells (SOFCs). The BCFZY powder was first synthesized via sol-gel method and pelletized to use it as a target in PLD system. As a result, the PLD-deposited thin film showed nano-porous morphology, preferred nano-architecture for cathode in SOFCs, without generating or transforming to secondary phase. The applicability of the thin film BCFZY to SOFC cathode was even confirmed by fabricating an SOFC with BCFZY cathode and operating it at 500 °C, where stable open-circuit voltage of 1.13 V was measured for an hour.
关键词： Pulsed laser deposition,Oxygen reduction reaction,thin film,Solid oxide fuel cells,BCFZY
更新于2025-09-23 15:22:29
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Facile Preparation of Unsubstituted Iron(II) Phthalocyanine/Carbon Nitride Nanocomposites: A Multipurpose Catalyst with Reciprocally Enhanced Photo/Electrocatalytic Activity
摘要： The development of new catalytic materials is conducive to solving the global energy crisis and environmental problems. In this work, multipurpose catalyst unsubstituted iron(II) phthalocyanine/carbon nitride nanosheet (FePc/CN) nanocomposites were prepared by utilizing concentrated sulfuric acid as an ideal solvent of CN and unsubstituted FePc. Such FePc/CN nanocomposites exhibited improved photo/electrocatalytic activity which was enhanced reciprocally: the photocatalytic activity of CN was promoted by FePc anchoring, and the electrocatalytic activity of FePc was improved by CN doping. The photocatalytic performance of FePc/CN?0.3 nanocomposites was about 6.4 and 1.7 times as high as FePc and CN, which was attributed to two reasons: (1) the anchoring FePc on CN extended the visible-light absorption region of CN, (2) the electron transfer from excited FePc to CN hindered charge carriers recombination and thus enhanced the photoinduced carrier separation efficiency. Relative to FePc and CN, the onset potential of FePc/CN?0.3 was positively shifted by 52 and 174 mV, such higher oxygen reduction reaction activity was due to the uniform dispersion of FePc on the supporting material CN without aggregation, which led to improved conductivity and stability of nanocomposites. This approach will contribute to an inexpensive and convenient synthetic strategy of transition-metal-based nanostructures for functional applications in photovoltaic, electrochemical, and catalytic fields.
关键词： Unsubstituted iron(II) phthalocyanine,Oxygen reduction reaction,Multipurpose catalyst,Photocatalytic performance,Carbon nitride nanosheet
更新于2025-09-23 15:22:29
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Ordered Mesoporous C?N? with a Combined Triazole and Triazine Framework and Its Graphene Hybrids
摘要： Mesoporous carbon nitrides (MCN) with C3N4 stoichiometry could find applications in fields ranging from catalysis, sensing, and adsorption–separation to biotechnology. The extension of the synthesis of MCN with different nitrogen contents and chemical structures promises access to even a wide range of applications. Here we show mesoporous C3N5 with a combined triazole and triazine framework prepared via a simple self-assembly of 5-amino-1H-tetrazole (5-ATTZ). We are able to hybridize these nanostructures with graphene by using graphene–mesoporous silica hybrids as a template to tune the electronic properties. Density functional theory calculations in combination with various spectroscopic analyses clearly demonstrate that the C3N5 consists of 1 triazole and 2 triazine moieties. The triazole-based mesoporous C3N5 and its graphene hybrids are found to be highly active for oxygen reduction reaction (ORR) with a higher diffusion-limiting current density and a decreased overpotential than those of bulk g-C3N4. We expect that this simple approach to the triazole-based mesoporous C3N5 could be extended for the preparation of series of new class of MCN nanostructures and their hybrids.
关键词： oxygen reduction reaction,porous materials,electrocatalysts,N-rich carbon nitrides,structure
更新于2025-09-23 15:21:21
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Origin of the Overpotential for the Oxygen Evolution Reaction on a Well-defined Graphene Electrode Probed by in situ Sum Frequency Generation Vibrational Spectroscopy
摘要： To develop an efficient material for the cathode of the lithium-oxygen (Li-O2) secondary battery, the oxygen reduction and evolution reactions (ORR and OER) on a well-defined graphene monolayer have been investigated in a typical organic solvent, dimethyl sulfoxide (DMSO). The adsorption and desorption behaviors of the solvents on the graphene electrode surface were evaluated by an intrinsically surface-selective vibrational spectroscopy of sum frequency generation (SFG) during the ORR and OER. After the initial ORR depositing lithium peroxide (Li2O2) on the graphene electrode surface in a LiClO4/DMSO solution, the SFG spectroscopy revealed that the subsequent OER oxidizing the Li2O2 preferentially proceeds at the interface between the Li2O2 and graphene rather than that between the Li2O2 and bulk solution. Therefore, the OER tends to reduce the electric conductivity between the Li2O2 and graphene by decreasing their contact area before a large part of the deposited Li2O2 was oxidized, which elucidates the origin of the high overpotential for the OER.
关键词： oxygen reduction reaction,lithium-oxygen battery,oxygen evolution reaction,sum frequency generation vibrational spectroscopy,graphene electrode
更新于2025-09-23 15:21:01
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Controlled Nitrogen Doping of Graphene Quantum Dots Through Laser Ablation in Aqueous Solutions for Photoluminescence and Electrocatalytic Applications
摘要： Nitrogen-doped graphene quantum dots (N-GQDs) have promising applications in catalysis and photoluminescence, but many existing synthetic methods require uses of harsh chemicals, long reaction times, and complicated purification steps and have poor control over the surface functional groups. Laser ablation in liquid (LAL) is a promising alternative method to prepare nanomaterials because of its fast production, use of fewer chemicals, simple purification, and fewer byproducts and its control of the product by precise tuning of laser ablation parameters. We report the use of LAL to produce N-GQDs from carbon nano-onions in aqueous solutions of ammonia, ethylenediamine, and pyridine. The choice of these dopants allowed for tuning the overall nitrogen content and the distribution of functional groups that led to the control over the photoluminescence emission wavelengths and lifetimes. High concentrations of amine groups tended to red shift emission and exhibit shorter lifetimes, whereas pyridinic groups would blue shift the emission and exhibit longer lifetimes. The N-GQDs also showed a promising performance as electrocatalysts for reducing oxygen to hydrogen peroxide, an important chemical widely used in industrial applications. The N-GQDs exhibited both low overpotentials and high selectivity for a two-electron oxygen reduction pathway.
关键词： electrocatalysis,photoluminescence,lifetime,laser ablation in liquid,oxygen reduction reaction,Graphene quantum dots
更新于2025-09-16 10:30:52
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Carbon supported oxygen vacancy-rich Co3O4 for robust photocatalytic H2O2 production via coupled water oxidation and oxygen reduction reaction
摘要： Photocatalytic H2O2 production is a promising strategy to alleviate energy crisis since H2O2 is an important liquidus chemical and fuel. However, the following problems severely restrict the development of this technique: (1) low selectivity; (2) low stability (normally less than 5 short-time cycles); (3) fast charge recombination; (4) assistance of hole scavengers and (5) demand of O2 saturation. Herein, carbon supported oxygen vacancy-rich Co3O4 nanoplate (C-ovCo) is reported as an efficient photocatalyst for scavenger-free H2O2 production by coupled 2e– water oxidation (WOR) and 2e? oxygen reduction reaction (ORR) with low energy barrier of 1.1 eV. In this system, the oxygen vacancies can reduce the band gap, enhance the donor density, improve the charge separation and migration and work as WOR sites, while the carbon support accepts electrons and works as ORR sites. The photocatalysts exhibit an optimal H2O2 production rate of 3.78 mmol h–1 g–1 under visible light (λ ≥ 420 nm), an apparent quantum efficiency (AQE) of 16.7% at 420 nm, and a solar-to-chemical efficiency (SCC) of 0.4%. Moreover, the stability of over 720 h (30 long-time cycles) is also superior to the state-of-the-art photocatalytic systems.
关键词： Carbon supported oxygen vacancy-rich Co3O4,Coupled reaction,Photocatalytic H2O2 production,Oxygen reduction reaction,Water oxidation reaction
更新于2025-09-11 14:15:04
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Synthesis and luminescence properties of a novel dazzling red-emitting phosphor NaSr <sub/>3</sub> SbO <sub/>6</sub> :Mn <sup>4+</sup> for UV/n-UV w-LEDs
摘要： High-loading atomic cobalt (12.8 wt%) dispersed on nitrogen-doped graphene was successfully synthesized via considerably low temperature pyrolysis. The catalyst exhibits excellent electrocatalytic performance towards the oxygen reduction reaction with a large limiting diffusion current density of 5.60 mA cm?2 (10% higher than that of commercial Pt/C), and when acting as the air catalyst of Zn–air batteries, a high open-circuit voltage of 41.40 V and excellent power density are also achieved.
关键词： low-temperature pyrolysis,atomic cobalt,nitrogen-doped graphene,Zn–air batteries,oxygen reduction reaction
更新于2025-09-11 14:15:04