首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 421 毫秒
1.
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   

2.
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   

3.
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   

4.
Cathode oxygen reduction reaction (ORR) performance is crucial for power generation of microbial fuel cells (MFCs). The current study provides a novel strategy to prepare Fe/N-doped carbon (Fe/N/C) catalyst for MFCs cathode through high temperature pyrolyzing of biomass capsuling melamine resin polymer. The obtained Fe/N/C can effectively enhance activity, selectivity and stability toward 4 e ORR in pH neutral solution. Single chamber MFC with Fe/N/C air cathode produces maximum power density of 1166 mW m−2, which is 140% higher than AC cathode. The improved performance of Fe/N/C can be attributed to the involvement of nitrogen and iron species. The excellent stability can be attributed to the preferential structure of the catalyst. The moderate porosity of the catalyst facilitates mass transfer of oxygen and protons and prevents water flooding of triple-phase boundary where ORR occurs. The biomass particles encapsulated in the catalyst act as skeletons, which prevents catalyst collapse and agglomeration.  相似文献   

5.
The use of Pt-based cathode catalyst materials hinders the widespread application of anion exchange membrane fuel cells (AEMFCs). Herein, we present a non-precious metal catalyst (NPMC) material based on pyrolysed Fe and Co co-doped electrospun carbon nanofibres (CNFs). The prepared materials are studied as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts in alkaline and acidic environments. High activity towards the ORR in alkaline solution indicated the suitability of the prepared NPMCs for the application at the AEMFC cathode. In the AEMFC test, the membrane-electrode assembly bearing a cathode with the nanofibre-based catalyst prepared with the ionic liquid (IL) (Fe/Co/IL–CNF–800b) showed the maximum power density (Pmax) of 195 mW cm−2, which is 78% of the Pmax obtained with a commercial Pt/C cathode catalyst. Such high ORR electrocatalytic activity was attributed to the unique CNF structure, high micro-mesoporosity, different nature of nitrogen species and metal-Nx active centres.  相似文献   

6.
High-efficiency and economical electrocatalysts for electrochemical water splitting are the core component of the renewable energy conversion. Herein, a simple and economical strategy is described to synthesize a series of metal oxide decorated nitrogen-doped carbon nanotubes materials (N-CNT@Cu–Fe Oxide Alloy NPs) by utilizing carbon nanotubes as the substrate carrier material. Additionally, the polypyrrole (PPy) was served as both the nitrogen resource and the localizing agent to load the Cu–Fe oxide alloy. Moreover, the theoretical and test results indicated that the superior HER and ORR performance is mainly related to the synergistic effect between the nitrogen-doped CNT and metallic oxide alloy. In the series of catalysts we prepared, N-CNT@Cu1–Fe1 Oxide Alloy NPs exhibits more significant catalytic activity and better durability than other catalysts that we synthesized. Meanwhile, the catalyst shows the low Tafel slope of 68.28 mV dec?1 for HER and reaches 10 mA cm?2 at the overpotential of 375 mV. The K–L plot shows that the electron transfer number of N–CNF@Cu1–Fe1 Alloy NPs is 3.43.  相似文献   

7.
Doping carbon materials with Fe and N attracts great attention due to its promising application in preparing ORR electrode with high performance and low cost. Previously, Fe, N-codoped catalyst (Fe/N/C) had been synthesized via a simple one-pot method using carbon materials, dopamine and FeCl3 by our group. However, the unstable activity and low selectivity (electron transfer number of ∼3.5) are key problems that should be solved. Herein, trace sulfur has been introduced into Fe, N-codoped carbon black by using 2-mercaptoethanol as an adhesive sulfur precursor. By the doping of trace S atoms (∼0.25 at%) into Fe, N-codoped carbon frameworks, the ORR performance has been obviously improved simply without any re-treatment process, such as acid-etching or nitrogen supplement. The mechanism of this process has been systematically investigated by changing the amount of initial sulfur precursor. A moderate amount of trace sulfur can effectively enhance the ORR performance of Fe, N-codoped carbon black due to suitable interactions among Fe, N, S and C elements. Both the content and the state of Fe and N species on the surface of carbon black can be changed and controlled by trace sulfur. The as-synthesized 1.0 SFe/N/C catalyst exhibits a good ORR activity (E1/2 = 0.749 V, Jk = 54.56 mA cm−2) and a total 4-electron selectivity. 1.0 SFe/N/C also shows better catalytic stability and methanol tolerance than 20 wt% Pt/C.  相似文献   

8.
The exploitation of high efficiency non-precious metal electrocatalysts towards oxygen reduction reaction (ORR) is great significant for large-scale commercialization of next-generation fuel cells. In this work, we designed and fabricated a series of porous carbazole-based N and M (Co, Fe) doped carbon framework catalysts which were obtained by the pyrolysis of a N-rich hypercrosslinked polymers derived from Friedel–Crafts reaction (abbreviated as TSP-HCP-900) followed by the incorporation of metal into the as-resulted N rich carbon (abbreviated as M-TSP-HCP-900, M = Co, Fe). Based on the high specific surface, excellent porosity, large pyridine nitrogen content and synergistic catalytic effects between the N dopants and metal nanoparticles, the M-TSP-HCP-900 exhibited superior ORR catalytic activity. Among them, the Co-TSP-HCP-900 possesses better electrocatalysis, i.e., a high diffusion limiting current density of 4.74 mA cm?2, half-wave potential of 0.8 V (vs. RHE, the same below) and onset potential of 0.9 V were found, respectively. In addition, this catalyst also discloses an excellent methanol tolerance, better durability and a biased 4e? reaction pathway, which are comparable to state-of-the-art Pt/C catalysts. Taking advantage of mentioning above, the M-TSP-HCP-900 may hold great potentials as promising alternative of precious metal catalysts for electrochemical energy conversion and storage.  相似文献   

9.
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   

10.
Fe-Nx catalysts have received widespread attention in recent years due to their excellent catalytic performance, hoping to replace platinum for oxygen reduction reactions (ORR). In recent years, more studies have shown that when the catalyst contains two or more metals doped, its catalytic performance will be improved. Herein, using the high temperature pyrolysis method, through the incorporation of the second phase metal (Zr), melamine as the nitrogen source, and thiourea as the sulfur source, a high-activity carbon-based catalyst doped with Fe and Zr bimetals was synthesized. Originating from the strong interaction between Fe species and ZrO2 clusters and the promotion of O2 adsorption by ZrO2 nanoparticles supported on nitrogen-doped carbon, this catalyst has a better ORR electrocatalytic performance than 46% TKK commercial platinum carbon in 0.1 M KOH, exhibiting an onset potential of 1.047 V vs RHE, a half-wave potential of 0.909 V vs RHE. It provides a new idea for the preparation of high-performance bimetallic-doped carbon-based electrocatalysts.  相似文献   

11.
A Ti–Co–Phen/C catalyst was prepared for polymer electrolyte membrane fuel cells (PEMFCs) without precious metals using a modified polymer complex (PC) method with 1,10-phenanthroline (Phen) as the nitrogen precursor. The oxygen reduction reaction (ORR) activity of the Ti–Co–Phen/C catalyst was significantly higher than the ORR activity of the Ti–Co/C catalyst prepared with the PC method because the former had a larger N surface content due to its highly dispersed Co species. The catalyst also exhibited excellent chemical stability in acidic media due to the probable strong interactions between the highly dispersed Ti and Co species. A H2/O2 PEMFC using the Ti–Co–Phen/C catalyst as the cathode demonstrated excellent cell performance. A 0.68 W cm−2 maximum power density was obtained. The cell performance stability did not drop perceptibly during its 550-h lifetime at 0.5 V and its 300-h lifetime at 0.7 V. The prepared Ti–Co–Phen/C catalyst exhibited both high ORR activity and excellent performance stability, making it a promising alternative for the cathode catalysts in PEMFCs.  相似文献   

12.
The most ideal substitute for Pt/C to catalyze the oxygen reduction reaction (ORR) is the transition metal and nitrogen co-doped carbon-based material (TM-N-C). However, large particles with low catalytic activity are formed easily for the transition metals during high-temperature carbonization. Herein, PAN nanofibers uniformly distributed with FeCl3 were coated with SiO2 and then carbonized to obtain Fe–N–Si tri-doped carbon nanofibers catalyst (Fe–N–Si-CNFs). The SiO2 can further anchor the Fe atoms, thus preventing agglomeration during the carbonization process. Meanwhile, Si atoms have been doped in CNFs during this process, which is conducive to the further improvement of catalytic performance. The Fe–N–Si-CNFs catalyst has a 3D network structure and a large specific surface area (809.3 m2 g−1), which contributes to catalyzing the ORR. In alkaline media, Fe–N–Si-CNFs exhibits superior catalytic performance (E1/2 = 0.86 V vs. RHE) and higher stability (9.6% activity attenuation after 20000s) than Pt/C catalyst (20 wt%).  相似文献   

13.
Transition metal on nitrogen-doped carbons (M-N-C, M = Fe, Co, Mn, etc.) are a group of promising sustainable electrocatalysts toward oxygen reduction reaction (ORR). Compared to its Fe, Co analogues, Mn–N–C possesses the advantage of being inert for catalyzing Fenton reaction, and thus is expected to offer higher durability, but its ORR activity needs essential improvement. Herein, an efficient Mn–N–C ORR catalyst composed of Mn3O4 nanoparticles supported on nitrogen-doped carbon was successfully synthesized by pyrolysis of cyanamide/Mn-incorporated polydopamine (PDA) film coated carbon black (CB), where the presence of N-rich cyanamide confers abundant Mn-Nx active sites and rich micropore/mesopores to the catalyst. In an alkaline medium, as-synthesized Mn–N–C electrocatalyst outperforms commercial Pt/C catalyst in terms of onset potential (0.98 V, vs. RHE), half-wave potential (0.868 V, vs. RHE), and limiting current density. Meanwhile, it exhibits excellent durability and resistance to methanol. In a Zinc-air primary battery, it demonstrates better performance as a cathodic catalyst than Pt/C.  相似文献   

14.
Preparation of high-efficiency oxygen reduction reaction (ORR) catalysts with abundant and inexpensive biomass materials have been a hot research topic. We use nitrogen-rich lentinus edodes and potassium ferrate (K2FeO4) to simultaneously activate the carbon material and prepare prussian blue (PB), and a porous carbon composite (PB/C) containing PB is synthesized. Finally, using ammonium chloride (NH4Cl) as a nitrogen source to further synthesize a Fe–N–C catalyst (PB/CN1T800) containing a trace amount of Fe for ORR. Results show that the prepared PB/CN1T800 catalyst forms a coral-like structure, which mainly contains mesopores and possesses a large specific surface area of approximately 1582 m2 g−1. Moreover, the onset potential of PB/CN1T800 is 0.95 V, and the half-wave potential is 0.83 V, which are consistent with those of commercial Pt/C. Thus the PB/CN1T800 material is an ORR catalyst with excellent performance. This work provides a basis for simple and efficient conversion of rich biomass into PB/porous carbon composites to prepare highly efficient catalysts.  相似文献   

15.
Metal and nitrogen co-doped catalysts have been promising alternatives to platinum group metal (PGM) catalysts for oxygen reduction reaction (ORR) over the past few decades. Herein, we have synthesized an efficient Fe–N–C catalyst by the co-calcination of NH2-MIL-101@PDA and melamine. The best Fe–N–C shows a positive half-wave potential of 0.844 V, which is 14 mV higher than that of Pt/C catalyst, as well as superior methanol resistance and long-term durability in alkaline electrolyte. In addition, Fe–N–C also exhibits pronounced catalytic activity and a direct 4e reaction pathway in acid electrolyte. We ascribed the excellent ORR performance of Fe–N–C to its crumpled structure, large specific surface area (584.6 m2 g−1) and high content of Fe-Nx sites (1.22 at. %). This study provides a simple way for the fabrication of excellent PGM-free ORR catalysts.  相似文献   

16.
The most promising non-precious metal oxygen reduction catalysts are M-Nx/C (M = Fe and/or Co) materials. Moreover, N-containing precursor is one of the important factors that affect oxygen reduction reaction (ORR) activity of M-Nx/C materials. In this paper, we want to study nitrogen precursor effects on ORR activity of Co-Nx/C catalysts by varying N content and N/C ratio of the nitrogen precursor. In this regard, three Co-Nx/C catalysts were synthesized using a solvent-milling method followed by high temperature treatment. The results showed that the increase in N content and N/C ratio did not necessarily cause the improvement of ORR activity of the Co-Nx/C catalyst. The most active catalyst, Co-HQ/C-800 (heat treatment of carbon supported Co-HQ complex at 800 °C for 2 h), was obtained using 8-hydroxyquinoline (8-HQ) as the nitrogen precursor. XPS analysis demonstrated that more graphitic N and Co-Nx active sites were responsible for better ORR activity of the Co-HQ/C-800 catalyst. The electrochemical property of the three Co-Nx/C catalysts was evaluated by linear sweep voltammetry (LSV), chronoamperometric measurements, accelerated durability tests (ADT) and H2/O2 alkaline fuel cell (AFC) tests.  相似文献   

17.
It is still a great challenge for developing efficient dual-functional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The electrocatalysts are critical to enhance the efficiency of metal-air cells and fuel cells. In this study, a one-pot vapor deposition method was used to realize the synchronously dope of N and Ni (trace) into Co/C to form Co–Ni (trace)/N-doped carbon nanotubes (Co–Ni (trace)/NCNTs). An interesting result is that injecting dicyandiamide (DCD) into Ni foam as a precursor led to the in situ formation of NCNTs, with synchronous doping of trace Ni into Co species. The cooperative effects of the Co–Ni (trace) and N-doped carbon nanotubes resulted in superior dual-functional electrocatalytic performance of Co–Ni (trace)/NCNTs for the ORR (half-wave potential E1/2 vs. RHE: 0.83 V, electron transfer number n: 3.97) and OER (overpotential vs. RHE: 337 mV at 10 mA cm?2, Tafel slope: 94.0 mV dec?1). Moreover, the Co–Ni (trace)/NCNTs catalyst showed excellent stability during 20,000 s of durability testing for both ORR and OER. This study provides a feasible strategy for designing efficient nonnoble metal-catalysts for renewable energy conversion devices.  相似文献   

18.
Noble metal Pt is the acknowledged efficient catalyst for oxygen reduction (ORR) and hydrogen evolution reaction (HER) in commercial applications. However, due to its high price and limited reserves, its large-scale application is limited. In order to overcome this defect, the loaded Pt nanoparticles (NPs) should be small and dispersed efficiently through the design of electrode materials, so as to improve the utilization efficiency of Pt. In addition, the introduction of non-noble metal active sites can reduce the consumption of Pt efficiently. In this work, hollow graphene spheres are used as the carrier and the heteroatoms (N, Fe and Co) are introduced. The results show that the introduction of Fe and Co can form very effective heteroatom active sites (carbon encapsulated Fe/Co metals and FeCo alloy, and/or metal nitrides Fe/Co-Nx-C) in the substrate material, which improve the catalytic activity of the electrode material effectively and the utilization efficiency of Pt. In addition, the generation of Fe/Co-Nx-C active sites and the loading of Pt are also closely related to the doped N atoms. The onset potential, limiting current density (JL), half-wave potential (E1/2) and Tafel slope of sample FeCo-NxHGSs/Pt (10 wt%) can exceed or comparable to those of commercial catalysts Pt/C (20 wt%) towards ORR both in acid and alkaline electrolyte. Moreover, the values of η100 and the Tafel slope for FeCo-NxHGSs/Pt towards HER can also exceed the commercial catalysts Pt/C (20 wt%) in acid and alkaline electrolytes. The purpose of reducing the usage amount of precious metals without reducing the catalytic performance is realized. The relationship between the ORR and HER performance of the resultant electrode catalyst and the doped heteroatoms, such as nitrogen (N), iron (Fe) and cobalt (Co) atoms, was studied and discussed in detail.  相似文献   

19.
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   

20.
Developing non-precious metal-based catalysts as the substitution of precious catalysts (Pt/C) in oxygen reduction reaction (ORR) is crucial for energy devices. Herein, a template and organic solvent-free method was adopted to synthesize Fe, B, and N doped nanoflake-like carbon materials (Fe/B/N–C) by pyrolysis of monoclinic ZIF-8 coated with iron precursors and boric acid. Benefiting from introducing B into Fe–N–C, the regulated electron cloud density of Fe-Nx sites enhance the charge transfer and promotes the ORR process. The as-synthesized Fe/B/N–C electrocatalyst shows excellent ORR activity of a half-wave potential (0.90 V vs 0.87 V of Pt/C), together with superior long-term stability (95.5% current density retention after 27 h) in alkaline media and is even comparable to the commercial Pt/C catalyst (with a half-wave potential of 0.74 V vs 0.82 V of Pt/C) in an acidic electrolyte. A Zn-air battery assembled with Fe/B/N–C as ORR catalyst delivers a higher open-circuit potential (1.47 V), specific capacity (759.9 mA h g?1Zn at 10 mA cm?2), peak power density (62 mW cm?2), as well as excellent durability (5 mA cm?2 for more than 160 h) compared to those with commercial Pt/C. This work provides an effective strategy to construct B doped Fe–N–C materials as nonprecious ORR catalyst. Theoretical calculations indicate that introduction of B could induce Fe-Nx species electronic configuration and is favorable for activation of OH1 intermediates to promote ORR process.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号