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Gold doping induced strong enhancement of carbon quantum dots fluorescence and oxygen evolution reaction catalytic activity of amorphous cobalt hydroxide
摘要： Gold doping induced strong enhancement of carbon quantum dots fluorescence and oxygen evolution reaction catalytic activity of amorphous cobalt hydroxide. Water splitting using electrocatalysts is expected to provide an alternative green energy source to meet increasing energy demands as well as addressing environmental concerns related to fossil fuels. Herein, we report one-step synthesis of sulfur, nitrogen and Au-doped carbon quantum dots (Au-SCQDs) and strong enhancement of fluorescence intensity and oxygen evolution reaction (OER) catalytic activity of amorphous Co(OH)2 nanoparticles compared to pure Co(OH)2 as well as commercial RuO2 and Pt/C catalysts. Au doping into sulfur and nitrogen co-doped CQDs showed over seventy times enhanced fluorescence. OER studies of amorphous-Co(OH)2 incorporated Au-SCQDs produced current density of 178 mA cm?2 at the applied potential of 2.07 V whereas un-doped Co(OH)2 showed current density of 59 mA cm?2. To produce geometric current density of 10 mA cm?2, amorphous Co(OH)2-Au-SCQDs (CSA) required 388–456 mV overpotential depending on the Au ion concentration used for preparing the Au-SCQDs, which is equal to or lower than overpotential required by commercial electrocatalysts. The strongly enhanced OER activity of Co(OH)2-Au-SCQDs (CSA) was attributed to the presence of electronegative metallic conducting Au atoms along with the high catalytic surface area of amorphous Co(OH)2. The present studies demonstrate a new method of exploiting amorphous Co(OH)2NPs electrocatalysts that could provide more catalytically active sites by integrating an electronegative conducting Au atom doped SCQDs matrix.
关键词： amorphous cobalt hydroxide,fluorescence,water splitting,Gold doping,carbon quantum dots,oxygen evolution reaction,electrocatalysts
更新于2025-10-22 19:40:53
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Promotion of Overall Water Splitting Activity Over a Wide pH Range by Interfacial Electrical Effects of Metallic NiCo-nitrides Nanoparticle/NiCo <sub/>2</sub> O <sub/>4</sub> Nanoflake/graphite Fibers
摘要： Many efforts have been made to develop bifunctional electrocatalysts to facilitate overall water splitting. Here, a fibrous bifunctional 3D electrocatalyst is reported for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with high performance. The remarkable electrochemical performance is attributed of the catalysts to a number of factors: the metallic character of the three components (i.e., Ni3N, CoN, and NiCo2O4); the electronic structure, nanoflake-nanosphere network with abundant electroactive sites, and the electric field effect at the interfaces between different components. The oxide–nitride/graphite fibers have the lowest overpotential requirements of 71 and 183 mV at 10 mA cm?2 for HER and OER in alkaline medium, respectively. These values are comparable to those of commercial Pt/C (20 wt%) and RuO2. The electrodes also show a response to HER and OER in both neutral and acid media. Furthermore, the 3D structure can be highlighted by all-round electrodes for overall water splitting. The calculations on the changes in electrons transfer and the Femi level from oxides to oxides/nitrides reveal that the observed superb electrocatalytic performance can be attributed to the presence of Ni3N and CoN derived from the in situ nitridation of NiCo2O4.
关键词： electrocatalysts,overall water splitting,interfacial electrical effects
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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Mo-doped Zn, Co Zeolitic-Imidazolate Framework-derived Co9S8 Quantum Dots and MoS2 Embedded in Three-Dimensional Nitrogen Doped Carbon Nano???ake Arrays as an Efficient Trifunctional Electrocatalysts for ORR, OER and HER
摘要： Herein, we first propose a facile strategy to synthesize Co9S8 and MoS2 nanocrystals embedded in porous carbon nanoflake arrays supported on carbon nanofibers (Co9S8-MoS2/N-CNAs@CNFs) by the pyrolysis of Mo-doped Zn, Co zeolitic-imidazolate framework grown on carbon nanofibers and subsequent sulfuration. The electrocatalyst shows high and stable electrocatalytic performance, with half-wave potential of 0.82 V for ORR and overpotential at 10 mA cm-2 for OER (0.34 V) and HER (0.163 V), which outperform the metal-organic frameworks-derived transition metal sulfide catalysts reported so far. Furthermore, the Co9S8-MoS2@N-CNAs@CNFs are employed as an air cathode in a liquid-state and all-solid-state zinc-air battery, presenting high power density of 222 mW cm-2 and 96 mW cm-2, respectively. Such excellent catalytic activities are mainly owing to the unique three-dimensional structure and chemical compositions, optimal electronic conductivity, adequate surface area and the abundance of active sites. Thus, this work provides an important method for designing other metal-organic frameworks derived three-dimensional structural sulfide quantum dot multifunctional electrocatalyst for wider application in highly efficient catalysis and energy storage.
关键词： zeolitic-imidazolate framework,Co9S8 quantum dots,MoS2,nitrogen-doped carbon nanoflakes arrays,Zn-air battery,trifunctional electrocatalysts
更新于2025-09-23 15:19:57
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Enhancing Electrocatalytic Water Splitting Activities via Photothermal Effect over Bifunctional Nickel/Reduced Graphene Oxide Nanosheets
摘要： Electrocatalytic water splitting has huge potential for generating hydrogen fuel. Its wide application suffers from high energy loss and sluggish reaction kinetics. The adoption of appropriate electrocatalysts is capable of reducing the overpotential and accelerating the reaction. Present research mainly focuses on adjusting electrocatalysts, but the performances are also dependent on other parameters. Therefore, the development of an efficient strategy to enhance electrocatalytic performance through integrating with other driving force, especially a renewable driving force, is of great interest. Herein, we present a photothermal-effect-driven strategy to promote the electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities of nickel/reduced graphene oxide (denoted as Ni/RGO) bifunctional electrocatalysts. The Ni/RGO composite exhibited significant enhancement of activities after exposure to light irradiation (49 mV and 50 mV decrease of overpotential at 10 mA/cm2 for HER and OER, respectively). It was found that the improved electrocatalytic activities arose from the photothermal effect of Ni/RGO, which can efficiently facilitate the thermodynamics and kinetics of electrocatalytic reactions. Furthermore, the photothermal-effect-induced enhancement for electrocatalysis showed good stability, indicating its promising potential in practical application.
关键词： Bifunctional electrocatalysts,Oxygen evolution reaction,Ni/RGO nanosheets,Photothermal effect,Hydrogen evolution reaction
更新于2025-09-19 17:15:36
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Hierarchical CoFe-Layered double hydroxide and g-C3N4 heterostructures with enhanced bifunctional photo/ electrocatalytic activity towards overall water splitting
摘要： To achieve sustainable and clean energy for the hydrogen economy, developing efficient earth-abundant and non-noble transition metal photo/electrocatalysts toward overall water splitting is highly desirable. In this work, layered double hydroxide (LDH)@g-C3N4 composites with hierarchical flower-like micro/nanosheets and high surface area have been synthesized by a solvothermal method. HRTEM images exhibit that the surface of g-C3N4 nanosheets is highly orientation with the main exposure of (002) plane. Compared with the pristine CoFe-LDH, the hierarchical nanocomposite presents an excellent and stable electrocatalytic performance in 1.0 M KOH, with a small Tafel slope of 58 mV/dec and an overpotential of about 275 mV at a current density of 10 mA/cm2. Simultaneously, CoFe-LDH@g-C3N4 exhibits an exceptional performance for the HER in 1.0 M KOH electrolyte, with the overpotential of 417 mV at a current density of 10 mA/cm2 and a small Tafel slope of 77 mV/dec. Therefore, this work not only accomplishes improved catalytic activity of the CoFe-LDH by the introduction of g-C3N4 nanosheets, but also provides an insight into the correlation between the hierarchical flower-like morphologies and photo/electrochemical catalytic activity for overall water splitting.
关键词： bifunctional activity,photo/electrocatalysts,hierarchical CoFe-LDH@g-C3N4,solvothermal method,overall water splitting
更新于2025-09-19 17:15:36
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A Scalable Laser-assisted Method to Produce Active and Robust Graphene-supported Nanoparticle Electrocatalysts
摘要： The development of renewable energy schemes requires the scalable production of highly robust electrocatalysts using a sustainable synthesis process that does not generate toxic liquid wastes. Here, an industrial laser system is utilized to prepare electrocatalysts in a continuous fashion using a laser-induced-forward-transfer-assisted nanomaterial preparation (LANP) method without generating liquid wastes. This dry processing method at room temperature and under ambient pressure enables the production of well-dispersed Pt, Ru, and Ni nanoparticles (NPs) supported on a few-layer graphene carbon framework. This versatile LANP procedure allows for the efficient deposition of binder-free Pt, Ru, and Ni NPs onto flexible polyimide films and glass surfaces at a rate of 400 mm/s. The size and quantity of the spherical NPs present on the conductive carbon surface can be tuned by adjusting the LANP parameters such as the laser power, the scribing speed, and the source thickness. Upon increasing the laser power, the Pt NPs size decreases, and the amount of Pt in the laser-derived materials increases. A second laser treatment can further modulate the hydrophilicity and solvent accessibility of graphene-supported Pt NPs. Our results demonstrate that the binder-free Pt, Ru, and Ni NPs supported on few-layer graphene generated using the LANP strategy can serve as practical, active, and robust electrocatalysts for water splitting reactions in advanced electrolyzer technology.
关键词： laser-assisted,graphene,electrocatalysts,water splitting,nanoparticles
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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Tracing the Origin of Visible Light Enhanced Oxygen Evolution Reaction
摘要： Hybrid nanostructures with a plasmonic core and catalytic shell often show significantly enhanced catalytic efficiency under illumination of specific frequency. Excitation of localized surface plasmonic resonance on plasmonic metals under illumination can generate hot electrons that assist in the catalytic reaction. However, the correlation between the microstructural geometry, dielectric environment, internal energy flow in the hybrid structure, and the chemical reaction rate is so far not clear. Here, a composite with a plasmonic Au metal yolk and a nearly transparent Ni3S2 shell is designed to maximize the absorption of incident light by forming strong localized surface plasmonic resonance at the yolk as predicted by 3D finite element method. The incoming photoenergy is dominantly dissipated on the shell by forming electron–hole pairs, leading to higher energy flow rate for oxygen evolution reaction. The overpotential is 252 mV at 10 mA cm?2 and the catalytic activity of Au@Ni3S2 achieves ca. 85-fold that of pure Ni3S2 under illumination and surpasses the commercial IrO2 catalyst. The study opens the door of exploration of highly effective hybrid composite catalysts for energy applications.
关键词： gold,localized surface plasmonic resonance (LSPR),nickel,photo-electrochemistry,electrocatalysts
更新于2025-09-10 09:29:36
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Layered Ternary and Quaternary Transition Metal Chalcogenide Based Catalysts for Water Splitting
摘要： Water splitting plays an important role in the electrochemical and photoelectrochemical conversion of energy devices. Electrochemical water splitting by the hydrogen evolution reaction (HER) is a straightforward route to producing hydrogen (H2), which requires an efficient electrocatalyst to minimize energy consumption. Recent advances have created a rapid rise in new electrocatalysts, particularly those based on non-precious metals. In this review, we present a comprehensive overview of the recent developments of ternary and quaternary 6d-group transition metal chalcogenides (TMCs) based electrocatalysts for water splitting, especially for HER. Detailed discussion is organized from binary to quaternary TMCs including, surface engineering, heterostructures, chalcogen substitutions and hierarchically structural design in TMCs. Moreover, emphasis is placed on future research scope and important challenges facing these electrocatalysts for further development in their performance towards water splitting.
关键词： transition metal,layered material,hierarchical,hydrogen,heterostructure,surface engineering,electrocatalysts
更新于2025-09-09 09:28:46