Scalable synthesis of bi-functional high-performance carbon nanotube sponge catalysts and electrodes with optimum C–N–Fe coordination for oxygen reduction reaction

Yang, Gang; Choi, Woongchul; Pu, Xiong; Yu, Choongho

doi:10.1039/c5ee00682a

Cited by 138 publications

(94 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To the best of our knowledge, our CNT@Fe-N-PC catalyst showed the best ORR performance in an acidic medium compared with all previously reported Fe-N-C and other non-noble-metal catalysts (Supplementary Table 2). 11,12,13,20,22,27,28,31,[37][38][39][40] In addition to the high activity, we further studied the durability of the CNT@Fe-N-PC catalyst. Figure 3c shows that the current density decay is 12% after 40 000 s of testing, much smaller than that (57%) of commercial Pt/C.…”

Section: Resultsmentioning

confidence: 99%

“…Notable progress has been made in recent years in the development of low-cost noble-metal-free catalysts, including heteroatom-doped carbon materials, 4-6 Fe 3 C-based materials [7][8][9] and transition-metalcoordinated nitrogen-doped carbon catalysts (Me-N-C, Me: Fe and/ or Co). [10][11][12] Although these materials demonstrate desirable ORR catalytic activity comparable to that of Pt/C in an alkaline medium, only Me-N-C catalysts, particularly Fe-N-C, show relatively good catalytic activity and durability in acidic conditions, [13][14][15] which makes them attractive for use in proton exchange membrane fuel cells. Fe-N-C catalysts are generally synthesized by pyrolyzing precursors containing carbon, nitrogen, and iron at temperatures above 700°C, to achieve high activity and a robust structure.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

N-doped carbon nanotubes containing a high concentration of single iron atoms for efficient oxygen reduction

et al. 2018

View full text Add to dashboard Cite

Fe-N-C has emerged as a promising noble-metal-free catalyst for the oxygen reduction reaction (ORR). However, achieving a catalytic activity comparable to that of Pt in acidic medium remains a great challenge. Here we report a N-doped carbon nanotube (CNT) catalyst in which a high concentration of single Fe atoms has been dispersed (CNT@Fe-N-PC). The catalyst was prepared by a simple and scalable atomic isolation method, in which a metal isolation agent was introduced to isolate Fe atoms and was then evaporated to produce abundant micropores that host single Fe atom active sites. The CNT@Fe-N-PC catalyst contained a high concentration of single Fe atom active sites and exhibited ultrahigh ORR activity with a half-wave potential of 0.82 V, comparable to that of Pt/C in an acidic medium. A high concentration of Fe-N x active sites was created on a flexible single-wall CNT film and carbon cloth using this technique, and these materials showed even better ORR performance, that is, 40-60 mV more positive onset potentials than those of a commercial Pt/C catalyst. These catalysts exhibit excellent catalytic activity, good durability and low cost, and show great potential for commercial use as substitutes for current Pt-based catalysts.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

N-doped carbon nanotubes containing a high concentration of single iron atoms for efficient oxygen reduction

et al. 2018

View full text Add to dashboard Cite

show abstract

“…1,2 A possible alternative is employing an anion exchange membrane (AEM) 3,4 that offers a less corrosive environment, so enabling the incorporation of non-PGM catalysts for oxygen reduction and evolution. Recent advances demonstrated activities comparable to that of platinum (Pt) for oxygen reduction in AEM fuel cells, [5][6][7][8][9] and to that of iridium oxide for oxygen evolution in AEM water electrolyzers. [10][11][12][13][14] However, for the hydrogen oxidation reaction (HOR) and the hydrogen evolution reaction (HER), Pt's activity remains superior to that of the non-PGM catalysts, 3 even though it is lower by two orders-of-magnitude from that in an acid environment.…”

Section: Introductionmentioning

confidence: 98%

Elucidating Hydrogen Oxidation/Evolution Kinetics in Base and Acid by Enhanced Activities at the Optimized Pt Shell Thickness on the Ru Core

et al. 2015

View full text Add to dashboard Cite

Hydrogen oxidation and evolution on Pt in acid are facile processes, while in alkaline electrolytes they are two-orders-of-magnitude slower. Thus, developing catalysts that are more active than Pt for these two reactions is important for advancing the performance of anionexchange-membrane fuel cells and water electrolyzers. Herein, we detail a four-fold enhancement in Pt mass activity that we achieved using single crystalline Ru@Pt core-shell nanoparticles with two-monolayer-thick Pt shells, which doubles the activity on Pt-Ru alloy nanocatalysts. For Pt specific activity, the 2-and 1-monolayer-thick Pt shells, respectively, exhibited an enhancement factor of 3.1 and 2.3 compared to the Pt nanocatalysts in base, differing considerably from the values of 1 and 0.4 in acid. To explain such behavior and the orders-of-magnitude difference in activity on going from acid to base, we performed kinetic analyses of polarization curves over a wide range of potential from -250 to 250 mV using the dual-pathway kinetic equation. From acid to base, the activation free energies increase the most for the Volmer reaction, resulting in a switch of the rate-determining step from the Tafel-to the Volmer-reaction, and a shift to a weaker optimal hydrogen-binding energy. The much higher activation barrier for the Volmer reaction in base than in acid is ascribed to one or both of the two catalyst-insensitive factors -slower transport of OH -than H + in water, and a stronger O-H bond in water molecules (HO-H) than in hydrated protons (H 2 O-H + ).

show abstract

“…Furthermore, utilizing the interconnected CNT network as the 3D porous template, a variety of hierarchical or hybrid composites have been derived with controlled microstructure and tailored properties. [170] Copyright 2015, The Royal Society of Chemistry. Energy application: CNT-based aerogels for catalysis.…”

Section: Discussionmentioning

confidence: 99%

“…[ 47 ] In addition to Pd, many different catalysts, such as TiO 2 [ 45,164,168 ] and CdS, [ 165 ] have been uniformly loaded into the CNT sponges initially described in the synthesis part or other forms of CNT macroscopic assemblies. [ 170 ] Compared with the Pt/C catalyst, the N-doped CNT sponges showed higher current density and stability (Figure 13 c-e). [ 165 ] Given the high cost of those noble metals (e.g., Pd and Pt), scientists have been searching for metal-free, inexpensive, high activity and durable substitute.…”

Section: Catalysismentioning

confidence: 98%

Carbon Nanotube Sponges, Aerogels, and Hierarchical Composites: Synthesis, Properties, and Energy Applications

Lin

Zeng

Gui

et al. 2016

Advanced Energy Materials

205

105

View full text Add to dashboard Cite

Carbon nanotube (CNT) aerogels and sponges are macroscopic porous materials with a unique isotropic structure. CNTs make an interconnected 3D scaffold, therefore the resulting aerogels are robust, highly conductive, and flexible, enabling a much broader range of applications than aligned arrays and thin films, especially in energy and environmental areas. A comprehensive overview of the recent progress in isotropic CNT‐based macroscopic structures is provided, including their synthesis methods, structural characteristics, mechanical properties, and deformation mechanism, as well as potential applications in energy and environmental fields. In particular, this study focuses on the CNT sponges developed, which are high‐performance porous materials with many distinct properties such as their versatile deformations and shape recovery. Importantly, the CNT sponges provide a universal platform for designing and manufacturing a variety of hierarchical functional composites by introducing polymers or inorganic guests, thus greatly extend application areas from highly compressible electrodes for supercapacitors and batteries, catalysis, to environmental cleanup. Future research directions and associated challenges in this field are proposed.

show abstract

Scalable synthesis of bi-functional high-performance carbon nanotube sponge catalysts and electrodes with optimum C–N–Fe coordination for oxygen reduction reaction

Abstract: Three-dimensional N/Fe-containing carbon nanotube sponges showing striking improvements in catalytic activity and stability were grown using a facile/scalable synthesis method.

Cited by 138 publications

References 47 publications

N-doped carbon nanotubes containing a high concentration of single iron atoms for efficient oxygen reduction

N-doped carbon nanotubes containing a high concentration of single iron atoms for efficient oxygen reduction

Elucidating Hydrogen Oxidation/Evolution Kinetics in Base and Acid by Enhanced Activities at the Optimized Pt Shell Thickness on the Ru Core

Carbon Nanotube Sponges, Aerogels, and Hierarchical Composites: Synthesis, Properties, and Energy Applications

Contact Info

Product

Resources

About