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1.
Silver nanocatalyst (40 wt%) is deposited on commercial mesoporous carbon support material (Ag/C) using two different wet chemical methods, to obtain high electrochemically active surface area. The catalyst materials are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetric analysis and are evaluated toward the oxygen reduction reaction (ORR) in alkaline media employing the rotating disk electrode method. It is worth noting that the Ag/C leads to oxygen reduction through a direct four-electron pathway in alkaline medium. The silver catalyst on mesoporous carbon exhibits relatively higher mass activity for ORR (38 A g−1) compared to that with Vulcan carbon (32 A g−1) at −0.2 V vs SCE at room temperature. Anion exchange membrane fuel cell shows maximum power density of 310 mW cm−2 with Ag/C cathode catalyst using H2 and O2 gases at 65% RH conditions at 65 °C.  相似文献   

2.
Sluggish kinetics and catalyst instability in oxygen reduction reaction are the central issues in fuel cell and metal-air battery technologies. For that, highly active, stable, and low-cost non-platinum based electrocatalysts for oxygen reduction reaction are an immediate requirement in fuel cell and metal-air battery technologies. A new composite (S,N-GQD/TiO2/C-800) is synthesized, made of sulfur (S) and nitrogen (N) co-doped graphene quantum dot (GQD) with TiO2. This composite is supported on carbon on heating at 800 °C under N2 atmosphere and is explored for oxygen reduction reaction (ORR) catalyst. The synthesized composite S,N-GQD/TiO2/C-800, shows outstanding catalytic activity with an onset potential of 0.91 V and a half-wave potential of 0.82 V vs. RHE, an alkaline medium. The Tafel slope of the catalyst is 61 mV dec?1. The catalyst is an excellent methanol tolerant and shows good stability in an alkaline medium. The excellent ORR activity of S,N-GQD/TiO2/C-800 is ascribed to well-built interactivity between the S,N-GQD/TiO2, and the carbon support. The unique structure offers advantages, with outstanding electrical conductivity, high surface area, and excellent charge transfer kinetics between the doped GQD and TiO2 interface and subsequently from the carbon surface to the S,N-GQD/TiO2.  相似文献   

3.
In this present study, novel hierarchical nitrogen-doped porous carbon for use as a metal-free oxygen reduction reaction (ORR) electrocatalyst is derived from borassus flabellifer male inflorescences by calcining at 1000 °C in an inert atmosphere using metal hydroxides as activating agent and melamine as nitrogen doping agent. The BET surface areas of the lithium-ion (Li-ion), potassium-ion (K-ion) and calcium-ion (Ca-ion) activated carbon are observed to be 824.02, 810.88 and 602.88 m2 g-1 respectively. Another interesting fact is that the total surface energy calculated by wicking method (73.2 mJ/m2), is found to be higher for Li-ion activated carbons. Among the prepared nitrogen-doped porous carbon, Li-ion activated system, showed an outstanding performance in ORR reaction in alkaline medium, thanks to its high surface area and notable surface activity. An incontrovertible of note that ORR half-wave potential of Li-ion activated nitrogen-doped carbon (0.90 V) is relatively higher in comparison to the commercial 20 wt % Pt/C catalyst (0.86 V). Inspite of overwhelming performance, the ORR reaction followed the preferred 4- electron transfer mechanism involving in the direct reduction pathway in all activated carbons. The ORR performance is also noticeably better and comparable to the best results in the literature based on biomass derived carbon catalysts.  相似文献   

4.
In this paper, iron and nitrogen co-doped carbon material with nanotube structure (Fe/N-CCM-T) was synthesized by pyrolyzing a mixture of Fe salt, chitosan and melamine and displayed high electrocatalytic performance for oxygen reduction reaction (ORR). The structure of the Fe/N-CCM-T was characterized and their ORR performance in alkaline media was investigated by linear sweep voltammetry, cyclic voltammetry and chronoamperometry. Fe/N-CCM-T displayed better ORR performance than other carbon materials like Fe/N-CC-800. The Fe/N-CCM-800 with a large surface area (302.5 m2/g) especially exhibited the best ORR electrocatalytic performance among the prepared carbon materials, which was also proved by its similar Tafel slope (76 mV decade?1) to Pt/C catalyst (74 mV decade?1). Fe/N-CCM-800 showed similar ORR activity as commercial Pt/C catalyst, but superior tolerance to methanol and stability. Such high ORR performance of the Fe/N-CCM-T can be attributed to its nanotube structure, high specific surface area (SSA), high graphitic-N and pyridinic-N contents.  相似文献   

5.
Morphology of carbon nanofibers significantly effects Pt nanoparticles dispersion and specific interaction with the support, which is an important aspect in the fuel cell performance of the electrocatalysts. This study emphasizes, the defects creation and structural evolution comprised due to N–F co-doping on graphitic carbon nanofibers (GNFs) of different morphologies, viz. GNF-linearly aligned platelets (L), antlers (A), herringbone (H), and their specific interaction with Pt nanoparticle in enhancing the oxygen reduction reaction (ORR). GNFs–NF–Pt catalysts exhibit better ORR electrocatalytic activity, superior durability that is solely ascribed to the morphological evolution and the doped N–F heteroatoms, prompting the charge density variations in the resultant carbon fiber matrices. Amongst, H–NF–Pt catalyst performed outstanding ORR activity with exceptional electrochemical stability, which shows only 20 mV loss in the half-wave potential whilst 100 mV loss for Pt/C catalyst on 20,000 potential cycling. The PEMFC comprising H–NF–Pt as cathode catalyst with minimum loading of 0.10 mg cm?2, delivers power density of 0.942 W cm?2 at current density of 2.50 A cm?2 without backpressures in H2–O2 feeds. The H–NF–Pt catalyst owing to its hierarchical architectures, performs well in PEMFC at the minimized catalyst loading with outstanding stability that can significantly decrease total price for the fuel cell.  相似文献   

6.
Designing oxygen reduction reaction (ORR) catalysts with high activity and long durability is significant for the development of proton exchange membrane fuel cells. Herein, the optimized platinum nanowires are used as templates for inducing growth of cobalt-containing metal-organic framework, deriving uniform nanofibers. After the calcination, the metal ions are transferred into the nitrogen-rich porous carbon, and wrapped by the carbon skeleton to form the PtCo bimetal incorporated nanofibers as high-performance ORR electrocatalyst. The Pt4Co@NC-900 catalyst yields high specific activity (1.37 mA cm−2) in comparison to Pt/C (0.38 mA cm−2). The mass activity (MA) of Pt4Co@NC-900 catalyst is approximately 3.8-fold higher than that of the commercial Pt/C under acidic conditions. After the accelerated durability tests, the Pt4Co@NC-900 catalyst presents only 16% loss in MA, while Pt/C catalyst retains 73.0% of the initial MA. The improved ORR performance can be ascribed to the synergistic interaction between Co and Pt.  相似文献   

7.
Evolution of highly durable electrocatalyst for oxygen reduction reaction (ORR) is the most critical barrier in commercializing polymer electrolyte membrane fuel cell (PEMFC). In this work, Pt deposited N-doped mesoporous carbon derived from Aloe Vera is developed as an efficient and robust electro catalyst for ORR. Due to its high mesoporous nature, the aloe vera derived carbon (AVC) play a very vital role in supporting Pt nanoparticles (NPs) with N-doping. After doping N into AVC, more defects are created which facilitates uniform distribution of Pt NPs leading to more active sites towards ORR. Pt/N-AVC shows excellent ORR activity when compared with commercial Pt/C and showing a half wave potential (E1/2–0.87 V Vs. RHE) and reduction potential (Ered ~ 0.72 V Vs. RHE) towards ORR. Even after 30,000 potential cycles, Pt/N-AVC shows in its E1/2 only ~5 mV negative shift and lesser agglomeration of Pt NPs is seen in the catalyst. In membrane electrode assembly (MEA) fabrication, Pt/N-AVC as a cathode catalyst in a PEMFC fixture and performance were studied. The Pt/N-AVC shows good performance, which proves the potential application of this naturally available bio derived carbon, which serves as an excellent high durable support material in PEMFC. All these features show that the Pt/N-AVC is the most stable, efficient and suitable candidate for ORR catalyst.  相似文献   

8.
Porous boron-bearing Fe-nitrogen doped carbon electrocatalysts (Fe-BNC) are prepared by pyrolysis treatment of Fe/B co-doped zeolitic imidazolate frameworks (ZIFs). The as-obtained Fe-BNC catalysts with a high surface area (1300 m2 g−1) favor a 4-electron reduction pathway for efficient oxygen reduction reaction (ORR). The Fe-BNC catalysts demonstrate a half-wave potential of ∼0.85 V vs RHE comparable to that of Pt/C catalyst and high stability in 0.1 M KOH. The dopant of little boron and iron into nitrogen-doped carbon results in the high surface area, enhanced surface polarities, electronic properties and exposing more active sites to introduce a synergistic effect for enhanced ORR performance. Moreover, Fe-BNC electrocatalysts used as air cathode for Al-air batteries exhibit a high peak power density of 195.2 mw cm−2 and excellent stability even after discharging for 24 h at room temperature, revealing an excellent performance in application of metal-air batteries and other energy converting devices.  相似文献   

9.
In this research, the activity of Fe–Co/KB (ketjenblack carbon) has been studied as a cathode catalyst for oxygen reduction reaction (ORR) in phosphate buffer saline (PBS) in presence of a solution containing low concentrations of glucose and amino acids mixture (near to physiological tissue fluid in the human body). It is worthwhile to mention that Fe–Co/KB cathode catalyst with size of 3 nm, determined by TEM, indicated an exceptional selectivity towards ORR. Results also revealed that Fe–Co/KB has a higher activity compare to 80%wt Pt/C in ORR with a superior tolerance towards poisoning agents.Further electrochemical investigations were carried out in a two-chamber implantable glucose fuel cell (IGFC) utilizing Fe–Co/KB in the cathode side. Time-dependent evaluation of cell voltage at constant current discharge 0.02 mAcm−2 in PBS (pH = 7.4) solution containing 5 mM glucose showed only 16% loss in cathode potential; demonstrating an acceptable performance of cathode catalyst in IGFC.  相似文献   

10.
11.
Rhodium with activated carbon as carbon base layer (Rh/AC) was exploited as an oxygen reduction reaction (ORR) catalyst to explore its applicability in microbial fuel cell (MFC). Four MFCs were fabricated using the Rh/AC catalyst, adopting varying Rh loadings of 0.5, 1.0 and 2.0 mg cm−2 and without Rh on carbon felt cathode in order to understand the optimum loading of this catalyst to enhance the performance of MFC. The participation of Rh/AC in ORR was confirmed by cyclic voltammetry and electron impedance spectroscopy analysis, which supported the enhanced charge transfer capacity of the cathode modified with the prepared catalysts. Volumetric power density of MFC was found to be improved by 2.6 times when Rh/AC was used as cathode catalyst (9.36 W m−3) at a loading of 2.0 mg cm−2 in comparison to the control MFC (3.65 W m−3) without Rh on the cathode. It was thus inferred that the increase in the Rh loading up to 2 mg cm−2 can improve the performance of MFC significantly.  相似文献   

12.
Heteroatoms-doped carbon-based materials (with non-precious metals or no metals) with porous structure have already shown high catalytic activities for oxygen reduction reaction (ORR), especially in microbial fuel cells (MFCs). Here, we use pectin extracted from pomelo peels as carbon source to prepare metal-free and sulphur/nitrogen co-doped partially-graphitized carbon (HP-SN-PGCs) by using silica nanospheres as sacrificial templates. Single-chamber MFC (SC-MFC) with HP-SN-PGC-0.5 (0.5 g of silica) cathode has the shortest start-up time (45 h) and lowest charge transfer resistance (19.3 Ω). The maximum power density of HP-SN-PGC-0.5 (1161.34 mW m−2) cathode is higher than that of Pt/C (1116.90 mW m−2) at the initial cycle. After 75 d operation, power density of HP-SN-PGC-0.5 cathode only declines 4.6%, which is more stable than that of Pt/C (37.69%). HP-SN-PGC-0.5 has a highly porous structure (869.25 m2 g−1) by removal of templates and Fe species (as the graphitization catalyst) to facilitate exposure of active sites and diffusion of ORR-related intermediates (OH and HO2, etc) to accessible active sites. N and S species provide highly active sites to enhance OH generation to conduct the 4e ORR process. Thus, this study presents a viable ORR catalyst with high activity and long-term stability for bio-electricity generation from organic wastewater in SC-MFCs.  相似文献   

13.
Oxygen reduction reaction (ORR) in Proton Exchange Membrane Fuel Cell (PEMFC) is the most sluggish reaction, which impedes the performance and commercialization of PEMFC. Platinum-based alloys show higher ORR activity than Pt and it is suggested by density functional theory calculations that Pt3Sc alloy has high stability and higher ORR activity due to filling the metal d-bands and lowers binding energy of the oxygen species respectively. Herein, we report Pt3Sc alloy nanoparticles (NPs) dispersed over partially exfoliated carbon nanotubes (PECNTs) as a cathode catalyst for single-cell measurements of PEMFC where Pt3Sc alloy shows a lower binding energy towards oxygen and facilitates ORR with much faster kinetics. The ORR activity of Pt3Sc/PECNTs electrocatalyst, investigated by cyclic voltammetry, Rotating Disk electrode (RDE) and Rotating Ring Disk electrode (RRDE), shows the higher mass activity and lower H2O2 formation than the commercial catalyst Pt/C-TKK. Accelerated Durability Tests (ADT) was performed to evaluate the stability of catalysts in acidic medium. In single-cell measurements, Pt3Sc/PECNTs cathode catalyst exhibits a power density of 760 mW cm−2 at 60 °C. Our study gives an important insight into the design of a novel ORR electrocatalyst with an excellent stability and high power density of PEMFC.  相似文献   

14.
Non-noble metal catalyst with high catalytic activity and stability towards oxygen reduction reaction (ORR) is critical for durable bioelectricity generation in air-cathode microbial fuel cells (MFCs). Herein, nitrogen-doped (iron-cobalt alloy)/cobalt/cobalt phosphide/partly-graphitized carbon ((FeCo)/Co/Co2P/NPGC) catalysts are prepared by using cornstalks via a facile method. Carbonization temperature exerts a great effect on catalyst structure and ORR activity. FeCo alloys are in-situ formed in the catalysts above 900 °C, which are considered as the highly-active component in catalyzing ORR. AC-MFC with FeCo/Co/Co2P/NPGC (950 °C) cathode shows the highest power density of 997.74 ± 5 mW m?2, which only declines 8.65% after 90 d operation. The highest Coulombic efficiency (23.3%) and the lowest charge transfer resistance (22.89 Ω) are obtained by FeCo/Co/Co2P/NPGC (950 °C) cathode, indicating that it has a high bio-electrons recycling rate. Highly porous structure (539.50 m2 g?1) can provide the interconnected channels to facilitate the transport of O2. FeCo alloys promote charge transfer and catalytic decomposition of H2O2 to ?OH and ?O2?, which inhibits cathodic biofilm growth to improve ORR durability. Synergies between metallic components (FeCo/Co/Co2P) and N-doped carbon energetically improve the ORR catalytic activity of (FeCo)/Co/Co2P/NPGC catalysts, which have the potential to be widely used as catalysts in MFCs.  相似文献   

15.
Iron, nitrogen, sulfur co-doped Fe/N/C catalyst (poly-AT/Me–Fe/N/C) with the structure of graphene-like nanosheets around carbon nanoparticles were successfully synthesized for oxygen reduction reaction (ORR). 2-Aminothiazole and melamine were utilized as the dual-nitrogen-source. The results showed that 2-Aminothiazole, as the nitrogen and sulfur source, contributed to in-situ synthesizing graphene-like nanosheets around KJ-600 carbon nanoparticles with high specific surface area (1098 m2/g). Proper method to introduce melamine during the synthesis could increase the content of pyridinic-N and Fe-Nx moieties in the catalyst without changing the morphology. Due to the high surface area and high content of pyridinic-N and Fe-Nx moieties, the obtained poly-AT/Me–Fe/N/C catalyst exhibited high electrochemical activity and stability with the half-wave potential of 0.84 V (RHE) in 0.1 M NaOH solution, which is merely 17 mV lower than commercial Pt/C. The electron transfer number was 3.83, indicating a nearly 4e? transfer for the ORR with low HO2? yield.  相似文献   

16.
Constructing highly efficient and durable non-noble metal modified carbon catalysts for oxygen reduction reaction (ORR) in the whole pH range is essential for energy conversion devices but still remains a challenge. Herein, the Fe/Fe3C nanoparticles and Fe-NX species anchored on the interconnected mesoporous carbon materials are fabricated through an economical and facile template-assisted polymerization-pyrolysis strategy. The catalyst exhibits unique features with the electronic interaction between Fe/Fe3C and Fe−NX, large specific surface area and high mesoporous structure as well as nitrogen doping in porous carbon skeletons, which can effectively catalyze ORR over the full pH range. In an alkaline electrolyte, the optimized catalyst displays favorable ORR performance with positive onset potential (Eonset = 0.91 V), half-wave potential (E1/2 = 0.83 V), long-term cycles stability and methanol tolerance, exceeding those for the commercial Pt/C. Furthermore, the prepared catalyst could be directly assembled into the alkaline Zn−air battery that exhibits the open-circuit voltage of 1.44 V, high power density of 96.0 mW cm−2 and long-term durability. Therefore, the template-assisted polymerization-pyrolysis strategy provides a promising route for designing high-performance non-noble metal decorated ORR electrocatalysts.  相似文献   

17.
Developing platinum-based nanoparticles on carbon catalysts with high activity and stability for oxygen reduction reaction (ORR) is of great significance for the practical application of fuel cells. Herein, a synchronous strategy of preparing nano-sized PtCo supported on atomic Co and N co-doped carbon nanorods (PtCo/Co–N–C NR) was developed to replace the conventional method of impregnating Pt sources into ready-made carbon materials, in which metal-organic frameworks (MOFs) with Co and Zn ions of rhombic dodecahedron were first prepared using 2-methylimidazole as building block and then their morphology was transformed into porous nanorods via the reduction of Co ions to Co–B–O complex in the MOFs by NaBH4; subsequently, Pt was deposited on the Co–Zn MOF nanorods through the displacement reaction of PtCl62- and metallic Co and coordination between MOF and PtCl62-; after pyrolysis and acid-leaching process, highly dispersed PtCo/Co–N–C NR was obtained. Attributed to its unique characteristics of hierarchical pore structure, uniform PtCo alloy nanoparticles with the average size of 7.0 nm and strong supporting interaction effect, the catalyst exhibits high ORR activity and stability with the mass activity of 577.0 mA mg?1Pt and specific activity of 1.4 mA cm?2 at 0.9 V vs RHE in 0.1 M HClO4, which is about 3.6 times and 3.5 times high than that of commercial Pt/C catalyst respectively. This strategy would provide a flexible route to develop highly active and stable ORR electrocatalysts with various morphologies for optimizing the exposure of active sites.  相似文献   

18.
Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the core reaction processes of rechargeable Zn-air battery (ZAB) cathode. Therefore, exploring a bifunctional catalyst with excellent electrochemical performance, high durability, and low cost is essential for rechargeable ZAB. In this work, amino functionalized carbon nanotubes supported core/shell nanoparticles composed of CoNi alloy core and CoO–NiO shell (CoNi@CoO–NiO/NH2-CNTs-1) is synthesized through a simple and efficient hydrothermal reaction and calcination method, which shows higher ORR/OER bifunctional catalytic performance than the single metal-based catalyst, such as Ni@NiO/NH2-CNTs and Co@CoO/NH2-CNTs. The fabricated bimetallic alloy based catalyst CoNi@CoO–NiO/NH2-CNTs-3 with the optimized loading content of CoNi@CoO–NiO core/shell nanoparticles, presents the best bifunctional catalytic performance for ORR/OER. Experimental studies reveal that CoNi@CoO–NiO/NH2-CNTs-3 exhibits the onset potential of 0.956 V and 1.423 V vs. RHE for ORR and OER, respectively. It also exhibits a low overpotential of 377 mV to achieve a 10 mA cm?2 current density for OER, and positive half-wave potentials of 0.794 V for ORR. And the potential difference between half-wave potential of ORR (E1/2) and the potential at 10 mA cm?2 for OER (Ej10) is 0.813 V. In addition, when CoNi@CoO–NiO/NH2-CNTs-3 is used as an air electrode catalyst of rechargeable ZAB, its maximum power density and open circuit voltage (OCV) can reach 128.7 mW cm?2 and 1.458 V (The commercially available catalyst of Pt/C–RuO2 is 88.1 mW cm?2), which strongly demonstrates that the fabricated catalyst CoNi@CoO–NiO/NH2-CNTs-3 can be used as a highly efficient bifunctional catalyst for ZABs, and is expected to replace those expensive precious metal electrocatalysts to meet the growing demand for new energy devices.  相似文献   

19.
Electrochemical reactions such as the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and methanol oxidation reaction (MOR) are essential for energy conversion applications such as water electrolysis and fuel cells. Furthermore, Pt or Ir-related materials have been extensively utilized as electrocatalysts for the OER, ORR, and MOR. To reduce the utilization of precious metals, innovative catalyst structures should be proposed. Herein, we report a bi-metallic phosphide (Ni2P and PdP2) structure surrounded by graphitic carbon (Ni–Pd–P/C) with an enhanced electrochemical activity as compared to conventional electrocatalysts. Despite the low Pd content of 3 at%, Ni–Pd–P/C exhibits a low overpotential of 330 mV at 10 mA cm?2 in the OER, high specific activity (2.82 mA cm?2 at 0.8 V) for the ORR, and a high current density of 1.101 A mg?1 for the MOR. The superior electrochemical performance of Ni–Pd–P/C may be attributed to the synergistic effect of the bi-metallic phosphide structure and core-shell structure formed by graphitic carbon.  相似文献   

20.
Transition metal iron-based catalysts are promising electrocatalysts for oxygen reduction reaction (ORR), and they have the potential to replace noble metal catalysts. The one-dimensional of carbon nanofibers with tubular structure can effectively promote the electrocatalytic activity, which facilitates electron transport. Herein, the Pt–Fe/CNFs were synthesized by electrospinning and subsequent calcination. Benefiting from the advantages of one-dimensional structure, Pt–Fe/CNFs-900 with fast electrochemical kinetics and excellent stability for ORR with excellent onset of 0.99 V, a low Tafel slope of 62 mV dec−1 and high limiting current density of 6.00 mA cm−2. Long-term ORR testing indicated that the durability of this catalyst was superior to that of commercial Pt/C in alkaline electrolyte. According to RRDE test, the ORR reaction process of Pt–Fe/CNFs-900 was close to four-electron transfer routes.  相似文献   

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