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1.
Highly Active and Stable Graphene Tubes Decorated with FeCoNi Alloy Nanoparticles via a Template‐Free Graphitization for Bifunctional Oxygen Reduction and Evolution
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Shiva Gupta Liang Qiao Shuai Zhao Hui Xu Ye Lin Surya V. Devaguptapu Xianliang Wang Mark T. Swihart Gang Wu 《Liver Transplantation》2016,6(22)
Development of highly active and stable bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts from earth‐abundant elements remains a grand challenge for highly demanded reversible fuel cells and metal–air batteries. Carbon catalysts have many advantages over others due to their low cost, excellent electrical conductivity, high surface area, and easy functionalization. However, they typically cannot withstand the highly oxidative OER environment. Here, a new class of bifunctional electrocatalyst is reported, consisting of ultralarge sized nitrogen doped graphene tubes (N‐GTs) (>500 nm) decorated with FeCoNi alloy particles. These tubes are prepared from an inexpensive precursor, dicyandiamide, via a template‐free graphitization process. The ORR/OER activity and the stability of these graphene tube catalysts depend strongly on the transition metal precursors. The best performing FeCoNi‐derived N‐GT catalyst exhibits excellent ORR and OER activity along with adequate electrochemical durability over a wide potential window (0–1.9 V) in alkaline media. The measured OER current is solely due to desirable O2 evolution, rather than carbon oxidation. Extensive electrochemical and physical characterization indicated that high graphitization degree, thicker tube walls, proper nitrogen doping, and presence of FeCoNi alloy particles are vital for high bifunctional activity and electrochemical durability of tubular carbon catalysts. 相似文献
2.
Qing Shi Qiao Liu Yu Ma Zhi Fang Zhao Liang Gang Shao Bin Tang Weiyou Yang Lin Qin Xiaosheng Fang 《Liver Transplantation》2020,10(10)
Currently, it is still a significant challenge to simultaneously boost various reactions by one electrocatalyst with high activity, excellent durability, as well as low cost. Herein, hybrid trifunctional electrocatalysts are explored via a facile one‐pot strategy toward an efficient oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The catalysts are rationally designed to be composed by FeCo nanoparticles encapsuled in graphitic carbon films, Co2P nanoparticles, and N,P‐codoped carbon nanofiber networks. The FeCo nanoparticles and the synergistic effect from Co2P and FeCo nanoparticles make the dominant contributions to the ORR, OER, and HER activities, respectively. Their bifunctional activity parameter (?E) for ORR and OER is low to 0.77 V, which is much smaller than those of most nonprecious metal catalysts ever reported, and comparable with state‐of‐the‐art Pt/C and RuO2 (0.78 V). Accordingly, the as‐assembled Zn–air battery exhibits a high power density of 154 mW cm?2 with a low charge–discharge voltage gap of 0.83 V (at 10 mA cm?2) and excellent stability. The as‐constructed overall water‐splitting cell achieves a current density of 10 mA cm?2 (at 1.68 V), which is comparable to the best reported trifunctional catalysts. 相似文献
3.
Controlling the Active Sites of Sulfur‐Doped Carbon Nanotube–Graphene Nanolobes for Highly Efficient Oxygen Evolution and Reduction Catalysis
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Abdelhamid M. El‐Sawy Islam M. Mosa Dong Su Curtis J. Guild Syed Khalid Raymond Joesten James F. Rusling Steven L. Suib 《Liver Transplantation》2016,6(5)
Controlling active sites of metal‐free catalysts is an important strategy to enhance activity of the oxygen evolution reaction (OER). Many attempts have been made to develop metal‐free catalysts, but the lack of understanding of active‐sites at the atomic‐level has slowed the design of highly active and stable metal‐free catalysts. A sequential two‐step strategy to dope sulfur into carbon nanotube–graphene nanolobes is developed. This bidoping strategy introduces stable sulfur–carbon active‐sites. Fluorescence emission of the sulfur K‐edge by X‐ray absorption near edge spectroscopy (XANES) and scanning transmission electron microscopy electron energy loss spectroscopy (STEM‐EELS) mapping and spectra confirm that increasing the incorporation of heterocyclic sulfur into the carbon ring of CNTs not only enhances OER activity with an overpotential of 350 mV at a current density of 10 mA cm?2, but also retains 100% of stability after 75 h. The bidoped sulfur carbon nanotube–graphene nanolobes behave like the state‐of‐the‐art catalysts for OER but outperform those systems in terms of turnover frequency (TOF) which is two orders of magnitude greater than (20% Ir/C) at 400 mV overpotential with very high mass activity 1000 mA cm?2 at 570 mV. Moreover, the sulfur bidoping strategy shows high catalytic activity for the oxygen reduction reaction (ORR). Stable bifunctional (ORR and OER) catalysts are low cost, and light‐weight bidoped sulfur carbon nanotubes are potential candidates for next‐generation metal‐free regenerative fuel cells. 相似文献
4.
Sebastian Wahl Sayed M. El‐Refaei Ana Guilherme Buzanich Patrick Amsalem Kug‐Seung Lee Norbert Koch Marie‐Liesse Doublet Nicola Pinna 《Liver Transplantation》2019,9(20)
To arrive to sustainable hydrogen‐based energy solutions, the understanding of water‐splitting catalysts plays the most crucial role. Herein, state‐of‐the‐art hypotheses are combined on electrocatalytic active metal sites toward the oxygen evolution reaction (OER) to develop a highly efficient catalyst based on Earth‐abundant cobalt and zinc oxides. The precursor catalyst Zn0.35Co0.65O is synthesized via a fast microwave‐assisted approach at low temperatures. Subsequently, it transforms in situ from the wurtzite structure to the layered γ‐Co(O)OH, while most of its zinc leaches out. This material shows outstanding catalytic performance and stability toward the OER in 1 m KOH (overpotential at 10 mA cm?2 ηinitial = 306 mV, η98 h = 318 mV). By comparing the electrochemical results and ex situ analyses to today's literature, clear structure‐activity correlations are able to be identified. The findings suggest that coordinately unsaturated cobalt octahedra on the surface are indeed the active centers for the OER. 相似文献
5.
Bimetallic Zeolitic Imidazolite Framework Derived Carbon Nanotubes Embedded with Co Nanoparticles for Efficient Bifunctional Oxygen Electrocatalyst
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Yinle Li Baoming Jia Yanzhong Fan Kelong Zhu Guangqin Li Cheng‐Yong Su 《Liver Transplantation》2018,8(9)
Bifunctional oxygen catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with high activities and low‐cost are of prime importance and challenging in the development of fuel cells and rechargeable metal–air batteries. This study reports a porous carbon nanomaterial loaded with cobalt nanoparticles (Co@NC‐x/y) derived from pyrolysis of a Co/Zn bimetallic zeolitic imidazolite framework, which exhibits incredibly high activity as bifunctional oxygen catalysts. For instance, the optimal catalyst of Co@NC‐3/1 has the interconnected framework structure between porous carbon and embedded carbon nanotubes, which shows the superb ORR activity with onset potential of ≈1.15 V and half‐wave potential of ≈0.93 V. Moreover, it presents high OER activity that can be further enhanced to over commercial RuO2 by P‐doped with overpotentials of 1.57 V versus reversible hydrogen electrode at 10 mA cm?2 and long‐term stability for 2000 circles and a Tafel slope of 85 mV dec?1. Significantly, the nanomaterial demonstrates better catalytic performance and durability than Pt/C for ORR and commercial RuO2 and IrO2 for OER. These findings suggest the importance of a synergistic effect of graphitic carbon, nanotubes, exposed Co–Nx active sites, and interconnected framework structure of various carbons for bifunctional oxygen electrocatalysts. 相似文献
6.
《Liver Transplantation》2018,8(1)
Nonprecious metal catalysts (NPMCs) Fe? N? C are promising alternatives to noble metal Pt as the oxygen reduction reaction (ORR) catalysts for proton‐exchange‐membrane fuel cells. Herein, a new modulation strategy is reported to the active moiety Fe? N4 via a precise “single‐atom to single‐atom” grafting of a Pt atom onto the Fe center through a bridging oxygen molecule, creating a new active moiety of Pt1? O2? Fe1? N4. The modulated Fe? N? C exhibits remarkably improved ORR stabilities in acidic media. Moreover, it shows unexpectedly high catalytic activities toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), with overpotentials of 310 mV for OER in alkaline solution and 60 mV for HER in acidic media at a current density of 10 mA cm?2, outperforming the benchmark RuO2 and comparable with Pt/C(20%), respectively. The enhanced multifunctional electrocatalytic properties are associated with the newly constructed active moiety Pt1? O2? Fe1? N4, which protects Fe sites from harmful species. Density functional theory calculations reveal the synergy in the new active moiety, which promotes the proton adsorption and reduction kinetics. In addition, the grafted Pt1? O2? dangling bonds may boost the OER activity. This study paves a new way to improve and extend NPMCs electrocatalytic properties through a precisely single‐atom to single‐atom grafting strategy. 相似文献
7.
Single‐Atom to Single‐Atom Grafting of Pt1 onto FeN4 Center: Pt1@FeNC Multifunctional Electrocatalyst with Significantly Enhanced Properties
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Xiaojun Zeng Jianglan Shui Xiaofang Liu Qingtao Liu Yongcheng Li Jiaxiang Shang Lirong Zheng Ronghai Yu 《Liver Transplantation》2018,8(1)
Nonprecious metal catalysts (NPMCs) Fe?N?C are promising alternatives to noble metal Pt as the oxygen reduction reaction (ORR) catalysts for proton‐exchange‐membrane fuel cells. Herein, a new modulation strategy is reported to the active moiety Fe?N4 via a precise “single‐atom to single‐atom” grafting of a Pt atom onto the Fe center through a bridging oxygen molecule, creating a new active moiety of Pt1?O2?Fe1?N4. The modulated Fe?N?C exhibits remarkably improved ORR stabilities in acidic media. Moreover, it shows unexpectedly high catalytic activities toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), with overpotentials of 310 mV for OER in alkaline solution and 60 mV for HER in acidic media at a current density of 10 mA cm?2, outperforming the benchmark RuO2 and comparable with Pt/C(20%), respectively. The enhanced multifunctional electrocatalytic properties are associated with the newly constructed active moiety Pt1?O2?Fe1?N4, which protects Fe sites from harmful species. Density functional theory calculations reveal the synergy in the new active moiety, which promotes the proton adsorption and reduction kinetics. In addition, the grafted Pt1?O2? dangling bonds may boost the OER activity. This study paves a new way to improve and extend NPMCs electrocatalytic properties through a precisely single‐atom to single‐atom grafting strategy. 相似文献
8.
Ultrafine Pt Nanoparticle‐Decorated Pyrite‐Type CoS2 Nanosheet Arrays Coated on Carbon Cloth as a Bifunctional Electrode for Overall Water Splitting
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Xiaopeng Han Xiaoyu Wu Yida Deng Jian Liu Jun Lu Cheng Zhong Wenbin Hu 《Liver Transplantation》2018,8(24)
To improve the utilization efficiency of precious metals, metal‐supported materials provide a direction for fabricating highly active and stable heterogeneous catalysts. Herein, carbon cloth (CC)‐supported Earth‐abundant CoS2 nanosheet arrays (CoS2/CC) are presented as ideal substrates for ultrafine Pt deposition (Pt‐CoS2/CC) to achieve remarkable performance toward the hydrogen and oxygen evolution reactions (HER/OER) in alkaline solutions. Notably, the Pt‐CoS2/CC hybrid delivers an overpotential of 24 mV at 10 mA cm?2 and a mass activity of 3.89 A Ptmg?1, which is 4.7 times higher than that of commercial Pt/C, at an overpotential of 130 mV for catalyzing the HER. An alkali‐electrolyzer using Pt‐CoS2/CC as a bifunctional electrode enables a water‐splitting current density of 10 mA cm?2 at a low voltage of 1.55 V and can sustain for more than 20 h, which is superior to that of the state‐of‐the‐art Pt/C+RuO2 catalyst. Further experimental and theoretical simulation studies demonstrate that strong electronic interaction between Pt and CoS2 synergistically optimize hydrogen adsorption/desorption behaviors and facilitate the in situ generation of OER active species, enhancing the overall water‐splitting performance. This work highlights the regulation of interfacial and electronic synergy in pursuit of highly efficient and durable supported catalysts for hydrogen and oxygen electrocatalytic applications. 相似文献
9.
FeN4 Sites Embedded into Carbon Nanofiber Integrated with Electrochemically Exfoliated Graphene for Oxygen Evolution in Acidic Medium
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Chaojun Lei Hengquan Chen Junhui Cao Jian Yang Ming Qiu Ying Xia Chris Yuan Bin Yang Zhongjian Li Xingwang Zhang Lecheng Lei Janel Abbott Yu Zhong Xinhui Xia Gang Wu Qinggang He Yang Hou 《Liver Transplantation》2018,8(26)
Development of inexpensive and efficient oxygen evolution reaction (OER) catalysts in acidic environment is very challenging, but it is important for practical proton exchange membrane water electrolyzers. A molecular iron–nitrogen coordinated carbon nanofiber is developed, which is supported on an electrochemically exfoliated graphene (FeN4/NF/EG) electrocatalyst through carbonizing the precursor composed of iron ions absorbed on polyaniline‐electrodeposited EG. Benefitting from the unique 3D structure, the FeN4/NF/EG hybrid exhibits a low overpotential of ≈294 mV at 10 mA cm?2 for the OER in acidic electrolyte, which is much lower than that of commercial Ir/C catalysts (320 mV) as well as all previously reported acid transitional metal‐derived OER electrocatalysts. X‐ray absorption spectroscopy coupled with a designed poisoning experiment reveals that the molecular Fe?N4 species are identified as active centers for the OER in acid. The first‐principles‐based calculations verify that the Fe?N4–doped carbon structure is capable of reducing the potential barriers and boosting the electrocatalytic OER activity in acid. 相似文献
10.
Fe?N4 Sites Embedded into Carbon Nanofiber Integrated with Electrochemically Exfoliated Graphene for Oxygen Evolution in Acidic Medium
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《Liver Transplantation》2018,8(26)
Development of inexpensive and efficient oxygen evolution reaction (OER) catalysts in acidic environment is very challenging, but it is important for practical proton exchange membrane water electrolyzers. A molecular iron–nitrogen coordinated carbon nanofiber is developed, which is supported on an electrochemically exfoliated graphene (FeN4/NF/EG) electrocatalyst through carbonizing the precursor composed of iron ions absorbed on polyaniline‐electrodeposited EG. Benefitting from the unique 3D structure, the FeN4/NF/EG hybrid exhibits a low overpotential of ≈294 mV at 10 mA cm?2 for the OER in acidic electrolyte, which is much lower than that of commercial Ir/C catalysts (320 mV) as well as all previously reported acid transitional metal‐derived OER electrocatalysts. X‐ray absorption spectroscopy coupled with a designed poisoning experiment reveals that the molecular Fe? N4 species are identified as active centers for the OER in acid. The first‐principles‐based calculations verify that the Fe? N4–doped carbon structure is capable of reducing the potential barriers and boosting the electrocatalytic OER activity in acid. 相似文献
11.
Katie L. Pickrahn Sang Wook Park Yelena Gorlin Han‐Bo‐Ram Lee Thomas F. Jaramillo Stacey F. Bent 《Liver Transplantation》2012,2(10):1269-1277
The ability to deposit conformal catalytic thin films enables opportunities to achieve complex nanostructured designs for catalysis. Atomic layer deposition (ALD) is capable of creating conformal thin films over complex substrates. Here, ALD‐MnOx on glassy carbon is investigated as a catalyst for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR), two reactions that are of growing interest due to their many applications in alternative energy technologies. The films are characterized by X‐ray photoelectron spectroscopy, X‐ray diffraction, scanning electron microscopy, ellipsometry, and cyclic voltammetry. The as‐deposited films consist of Mn(II)O, which is shown to be a poor catalyst for the ORR, but highly active for the OER. By controllably annealing the samples, Mn2O3 catalysts with good activity for both the ORR and OER are synthesized. Hypotheses are presented to explain the large difference in the activity between the MnO and Mn2O3 catalysts for the ORR, but similar activity for the OER, including the effects of surface oxidation under experimental conditions. These catalysts synthesized though ALD compare favorably to the best MnOx catalysts in the literature, demonstrating a viable way to produce highly active, conformal thin films from earth‐abundant materials for the ORR and the OER. 相似文献
12.
Yang Yang Lianna Dang Melinda J. Shearer Hongyuan Sheng Wenjie Li Jie Chen Peng Xiao Yunhuai Zhang Robert J. Hamers Song Jin 《Liver Transplantation》2018,8(15)
The development of efficient and robust earth‐abundant electrocatalysts for the oxygen evolution reaction (OER) is an ongoing challenge. Here, a novel and stable trimetallic NiFeCr layered double hydroxide (LDH) electrocatalyst for improving OER kinetics is rationally designed and synthesized. Electrochemical testing of a series of trimetallic NiFeCr LDH materials at similar catalyst loading and electrochemical surface area shows that the molar ratio Ni:Fe:Cr = 6:2:1 exhibits the best intrinsic OER catalytic activity compared to other NiFeCr LDH compositions. Furthermore, these nanostructures are directly grown on conductive carbon paper for a high surface area 3D electrode that can achieve a catalytic current density of 25 mA cm?2 at an overpotential as low as 225 mV and a small Tafel slope of 69 mV dec?1 in alkaline electrolyte. The optimized NiFeCr catalyst is stable under OER conditions and X‐ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, and elemental analysis confirm the stability of trimetallic NiFeCr LDH after electrochemical testing. Due to the synergistic interactions among the metal centers, trimetallic NiFeCr LDH is significantly more active than NiFe LDH and among the most active OER catalysts to date. This work also presents general strategies to design more efficient metal oxide/hydroxide OER electrocatalysts. 相似文献
13.
All‐In‐One Perovskite Catalyst: Smart Controls of Architecture and Composition toward Enhanced Oxygen/Hydrogen Evolution Reactions
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A conventional water electrolyzer consists of two electrodes, each of which is embedded with a costly and rare electrocatalyst, typically IrO2/C for oxygen evolution reaction (OER) and Pt/C for hydrogen evolution reaction (HER), respectively. HER and OER electrocatalysts usually require very different pH values to keep them stable and active. Thus, the development of earth‐abundant nonprecious metal catalysts for both HER and OER is of great importance to practical applications. This work reports the results of integrated water electrolysis using the hybrids of electrospun La0.5(Ba0.4Sr0.4Ca0.2)0.5Co0.8Fe0.2O3–δ (L‐0.5) perovskite nanorods attached to reduced graphene oxide (rGO) nanosheets as bifunctional electrodes. Via rationalizing the composition and morphology of L‐0.5/rGO nanohybrids, excellent catalytic performance and stability toward OER and HER are achieved in alkaline media. The operating voltage of integrated L‐0.5/rGO electrolyzer is tested to be 1.76 V at 50 mA cm–2, which is close to that of the commercially available IrO2/C‐Pt/C couple (1.76 V @ 50 mA cm–2). Such a bifunctional electrocatalyst could be extended toward practical electrolysis use with low expanse and high efficiency. More generally, the protocol described here broadens our horizons in terms of the designs and the diverse functionalities of catalysts for use in various applications. 相似文献
14.
Tiva Sharifi Eduardo Gracia‐Espino Anran Chen Guangzhi Hu Thomas Wgberg 《Liver Transplantation》2020,10(11)
The oxygen reduction reaction (ORR) is of great importance in energy‐converting processes such as fuel cells and in metal–air batteries and is vital to facilitate the transition toward a nonfossil dependent society. The ORR has been associated with expensive noble metal catalysts that facilitate the O2 adsorption, dissociation, and subsequent electron transfer. Single‐ or few‐atom motifs based on earth‐abundant transition metals, such as Fe, Co, and Mo, combined with nonmetallic elements, such as P, S, and N, embedded in a carbon‐based matrix represent one of the most promising alternatives. Often these are referred to as single atom catalysts; however, the coordination number of the metal atom as well as the type and nearest neighbor configuration has a strong influence on the function of the active sites, and a more adequate term to describe them is metal‐coordinated motifs. Despite intense research, their function and catalytic mechanism still puzzle researchers. They are not molecular systems with discrete energy states; neither can they fully be described by theories that are adapted for heterogeneous bulk catalysts. Here, recent results on single‐ and few‐atom electrocatalyst motifs are reviewed with an emphasis on reports discussing the function and the mechanism of the active sites. 相似文献
15.
Electronic and Defective Engineering of Electrospun CaMnO3 Nanotubes for Enhanced Oxygen Electrocatalysis in Rechargeable Zinc–Air Batteries
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Shengjie Peng Xiaopeng Han Linlin Li Shulei Chou Dongxiao Ji Huangjiao Huang Yonghua Du Jian Liu Seeram Ramakrishna 《Liver Transplantation》2018,8(22)
Rational design and massive production of bifunctional catalysts with superior oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities are essential for developing metal–air batteries and fuel cells. Herein, controllable large‐scale synthesis of sulfur‐doped CaMnO3 nanotubes is demonstrated via an electrospinning technique followed by calcination and sulfurization treatment. The sulfur doping can not only replace oxygen atoms to increase intrinsic electrical conductivity but also introduce abundant oxygen vacancies to provide enough catalytically active sites, which is further demonstrated by density functional theory calculation. The resulting sulfur‐modified CaMnO3 (CMO/S) exhibits better electrocatalytic activity for ORR and OER in alkaline solution with higher stability performance than the pristine CMO. These results highlight the importance of sulfur treatment as a facile yet effective strategy to improve the ORR and OER catalytic activity of the pristine CaMnO3. As a proof‐of‐concept, a rechargeable Zn–air battery using the bifunctional catalyst exhibits a small charge–discharge voltage polarization, and long cycling life. Furthermore, a solid‐state flexible and rechargeable Zn–air battery gives superior discharge–charge performance and remarkable stability. Therefore, the CMO/S nanotubes might be a promising replacement to the Pt‐based electrocatalysts for metal–air batteries and fuel cells. 相似文献
16.
Biswarup Chakraborty Rodrigo Beltrn‐Suito J. Niklas Hausmann Somenath Garai Matthias Driess Prashanth W. Menezes 《Liver Transplantation》2020,10(30)
A strategy to overcome the unsatisfying catalytic performance and the durability of monometallic iron‐based materials for the electrochemical oxygen evolution reaction (OER) is provided by heterobimetallic iron–metal systems. Monometallic Fe catalysts show limited performance mostly due to poor conductivity and stability. Here, by taking advantage of the structurally ordered and highly conducting FeSn2 nanostructure, for the first time, an intermetallic iron material is employed as an efficient anode for the alkaline OER, overall water‐splitting, and also for selective oxygenation of organic substrates. The electrophoretically deposited FeSn2 on nickel foam (NF) and fluorine‐doped tin oxide (FTO) electrodes displays remarkable OER activity and durability with substantially low overpotentials of 197 and 273 mV at 10 mA cm?2, respectively, which outperform most of the benchmarking NiFe‐based catalysts. The resulting superior activity is attributed to the in situ generation of α‐FeO(OH)@FeSn2 where α‐FeO(OH) acts as the active site while FeSn2 remains the conductive core. When the FeSn2 anode is coupled with a Pt cathode for overall alkaline water‐splitting, a reduced cell potential (1.53 V) is attained outperforming that of noble metal‐based catalysts. FeSn2 is further applied as an anode to produce value‐added products through selective oxygenation reactions of organic substrates. 相似文献
17.
Sharath Kandambeth Vinayak. S. Kale Dong Fan Jeremy A. Bau Prashant M. Bhatt Sheng Zhou Aleksander Shkurenko Magnus Rueping Guillaume Maurin Osama Shekhah Mohamed Eddaoudi 《Liver Transplantation》2023,13(1):2202964
Here, this work reports an innovative strategy for the synthesis of chemically robust metal–organic frameworks (MOFs), and applies them as catalysts for the electrocatalytic oxygen evolution reaction (OER). A bimetallic squarate-based MOF (Sq-MOF) with a zbr topology serves as an excellent platform for electrocatalytic OER owing to its open porous structure, high affinity toward water, and presence of catalytically active 1D metal hydroxide strips. By regulating the Ni2+ content in a bimetallic squarate MOF system, the electrochemical structural stability toward OER can be improved. The screening of various metal ratios demonstrates that Ni3Fe1 and Ni2Fe1 Sq- zbr -MOFs show the best performance for electrocatalytic OER in terms of catalytic activity and structural stability. Ni2Fe1 Sq- zbr -MOF shows a low overpotential of 230 mV (at 10 mA cm−2) and a small Tafel slope of 37.7 mV dec−1, with an excellent long-term electrochemical stability for the OER. Remarkably, these overpotential values of Ni2Fe1 Sq- zbr -MOF are comparable with those of the best-performing layered double hydroxide (LDH) systems and outperforms the commercially available noble-metal-based RuO2 catalyst for OER under identical operational conditions. 相似文献
18.
Xiaogang Fu Na Li Bohua Ren Gaopeng Jiang Yanru Liu Fathy M. Hassan Dong Su Jianbing Zhu Lin Yang Zhengyu Bai Zachary P. Cano Aiping Yu Zhongwei Chen 《Liver Transplantation》2019,9(11)
Transition metal atoms with corresponding nitrogen coordination are widely proposed as catalytic centers for the oxygen reduction reaction (ORR) in metal–nitrogen–carbon (M–N–C) catalysts. Here, an effective strategy that can tailor Fe–N–C catalysts to simultaneously enrich the number of active sites while boosting their intrinsic activity and utilization is reported. This is achieved by edge engineering of FeN4 sites via a simple ammonium chloride salt‐assisted approach, where a high fraction of FeN4 sites are preferentially generated and hosted in a graphene‐like porous scaffold. Theoretical calculations reveal that the FeN4 moieties with adjacent pore defects are likely to be more active than the nondefective configuration. Coupled with the facilitated accessibility of active sites, this prepared catalyst, when applied in a practical H2–air proton exchange membrane fuel cell, delivers a remarkable peak power density of 0.43 W cm?2, ranking it as one of the most active M–N–C catalysts reported to date. This work provides a new avenue for boosting ORR activity by edge manipulation of FeN4 sites. 相似文献
19.
Electrocatalytic Oxygen Evolution Reaction in Acidic Environments – Reaction Mechanisms and Catalysts
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Tobias Reier Hong Nhan Nong Detre Teschner Robert Schlögl Peter Strasser 《Liver Transplantation》2017,7(1)
The low efficiency of the electrocatalytic oxidation of water to O2 (oxygen evolution reaction‐OER) is considered as one of the major roadblocks for the storage of electricity from renewable sources in form of molecular fuels like H2 or hydrocarbons. Especially in acidic environments, compatible with the powerful proton exchange membrane (PEM), an earth‐abundant OER catalyst that combines high activity and high stability is still unknown. Current PEM‐compatible OER catalysts still rely mostly on Ir and/or Ru as active components, which are both very scarce elements of the platinum group. Hence, the Ir and/or Ru amount in OER catalysts has to be strictly minimized. Unfortunately, the OER mechanism, which is the most powerful tool for OER catalyst optimization, still remains unclear. In this review, we first summarize the current state of our understanding of the OER mechanism on PEM‐compatible heterogeneous electrocatalysts, before we compare and contrast that to the OER mechanism on homogenous catalysts. Thereafter, an overview over monometallic OER catalysts is provided to obtain insights into structure‐function relations followed by a review of current material optimization concepts and support materials. Moreover, missing links required to complete the mechanistic picture as well as the most promising material optimization concepts are pointed out. 相似文献
20.
Ultrafine Metal Nanoparticles/N‐Doped Porous Carbon Hybrids Coated on Carbon Fibers as Flexible and Binder‐Free Water Splitting Catalysts
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Yongqi Zhang Xinhui Xia Xun Cao Bowei Zhang Nguyen Huy Tiep Haiyong He Shi Chen Yizhong Huang Hong Jin Fan 《Liver Transplantation》2017,7(15)
By employing in situ reduction of metal precursor and metal‐assisted carbon etching process, this study achieves a series of ultrafine transition metal‐based nanoparticles (Ni–Fe, Ni–Mo) embedded in N‐doped carbon, which are found efficient catalysts for electrolytic water splitting. The as‐prepared hybrid materials demonstrate outstanding catalytic activities as non‐noble metal electrodes rendered by the synergistic effect of bimetal elements and N‐dopants, the improved electrical conductivity, and hydrophilism. Ni/Mo2C@N‐doped porous carbon (NiMo‐polyvinylpyrrolidone (PVP)) and NiFe@N‐doped carbon (NiFe‐PVP) produce low overpotentials of 130 and 297 mV at a current density of 10 mA cm?2 as catalysts for hydrogen evolution reaction and oxygen evolution reaction, respectively. In addition, these binder‐free electrodes show long‐term stability. Overall water splitting is also demonstrated based on the couple of NiMo‐PVP||NiFe‐PVP catalyzer. This represents a simple and effective synthesis method toward a new type of nanometal–carbon hybrid electrodes. 相似文献