Fe@N-Graphene Nanoplatelet-Embedded Carbon Nanofibers as Efficient Electrocatalysts for Oxygen Reduction Reaction.
Ontology highlight
ABSTRACT:
SUBMITTER: Ju YW
PROVIDER: S-EPMC5049621 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:One-dimensional electrospun nanofibers have emerged as a potential candidate for high-performance oxygen reduction reaction (ORR) catalysts. However, contact resistance among the neighbouring nanofibers hinders the electron transport. Here, we report the preparation of interconnected Fe-N/C nanofiber networks (Fe-N/C NNs) with low electrical resistance via electrospinning followed by maturing and pyrolysis. The Fe-N/C NNs show excellent ORR activity with onset and half-wave potential of 55 and 108?mV less than those of Pt/C catalyst in 0.5?M H2SO4. Intriguingly, the resulting Fe-N/C NNs exhibit 34% higher peak current density and superior durability than generic Fe-N/C ones with similar microstructure and chemical compositions. Additionally, it also displays much better durability and methanol tolerance than Pt/C catalyst. The higher electroactivity is mainly due to the more effective electron transport between the interconnected nanofibers. Thus, our findings provide a novel insight into the design of functional electrospun nanofibers for the application in energy storage and conversion fields.
| S-EPMC4663764 | biostudies-literature
Project description:A novel and facile two-step strategy has been designed to prepare high performance bi-transition-metals (Fe- and Mo-) carbide supported on nitrogen-doped graphene (FeMo-NG) as electrocatalysts for oxygen reduction reactions (ORR). The as-synthesized FeMo carbide -NG catalysts exhibit excellent electrocatalytic activities for ORR in alkaline solution, with high onset potential (-0.09 V vs. saturated KCl Ag/AgCl), nearly four electron transfer number (nearly 4) and high kinetic-limiting current density (up to 3.5 mA cm(-2) at -0.8 V vs. Ag/AgCl). Furthermore, FeMo carbide -NG composites show good cycle stability and much better toxicity tolerance durability than the commercial Pt/C catalyst, paving their application in high-performance fuel cell and lithium-air batteries.
| S-EPMC4441168 | biostudies-literature
Project description:The large-scale and controllable synthesis of novel N-doped three-dimensional (3D) carbon nanocage-decorated carbon skeleton sponges (Co-NCMS) is introduced. These Co-NCMS were highly active and durable non-noble metal catalysts for the oxygen reduction reaction (ORR). This hybrid electrocatalyst showed high ORR activity with a diffusion-limiting current of 5.237 mA·cm-2 in 0.1 M KOH solution through the highly efficient 4e- pathway, which was superior to that of the Pt/C catalyst (4.99 mA·cm-2), and the ORR Tafel slope is ca. 67.7 mV·dec-1 at a high potential region, close to that of Pt/C. Furthermore, Co-NCMS exhibited good ORR activity in acidic media with an onset potential comparable to that of the Pt/C catalyst. Most importantly, the prepared catalyst showed much higher stability and better methanol tolerance in both alkaline and acidic solutions. The power density obtained in a proton exchange membrane fuel cell was as high as 0.37 W·cm-2 at 0.19 V compared with 0.45 W·cm-2 at 0.56 V for the Pt/C catalyst. In Co-NCMS, the N-doped carbon nanocages facilitated the diffusion of the reactant, maximizing the exposure of active sites on the surface and protecting the active metallic core from oxidation. This made Co-NCMS one of the best non-noble metal catalysts and potentially offers an alternative approach for the efficient utilization of active transition metals in electrocatalyst applications.
| S-EPMC8358961 | biostudies-literature
Project description:Nanostructured FeS dispersed onto N, S dual-doped carbon nanotube-graphene composite support (FeS/N,S:CNT-GR) was prepared by a simple synthetic method. Annealing an ethanol slurry of Fe precursor, thiourea, carbon nanotube, and graphene oxide at 973 K under N2 atmosphere and subsequent acid treatment produced FeS nanoparticles distributed onto the N, S-doped carbon nanotube-graphene support. The synthesized FeS/N,S:CNT-GR catalyst exhibited significantly enhanced electrochemical performance in the oxygen reduction reaction (ORR) compared with bare FeS, FeS/N,S:GR, and FeS/N,S:CNT with a small half-wave potential (0.827 V) in an alkaline electrolyte. The improved ORR performance, comparable to that of commercial Pt/C, could be attributed to synergy between the small FeS nanoparticles with a high activity and the N, S-doped carbon nanotube-graphene composite support providing high electrical conductivity, large surface area, and additional active sites.
| S-EPMC8122905 | biostudies-literature
Project description:Electrocatalysts play an important role in oxygen reduction reaction (ORR) in promoting the reaction process. Although commercial Pt/C exhibits excellent performance in ORR, the low duration, high cost, and poor methanol tolerance seriously restrict its sustainable development and application. TinO2n-1 (3 ? n ? 10) is a series of titanium sub-oxide materials with excellent electrical conductivity, electrochemical activity, and stability, which have been widely applied in the field of energy storage and catalysis. Herein, we design and synthesize Ti4O7/Ti3O5 (T4/T3) dual-phase nanofibers with excellent ORR catalytic performance through hydrothermal growth, which is followed by a precisely controlled calcination process. The H2Ti3O7 precursor with uniform size can be first obtained by optimizing the hydrothermal growth parameters. By precisely controlling the amount of reducing agent, calcination temperature, and holding time, the T4/T3 dual-phase nanofibers with uniform morphology and coherent interfaces can be obtained. The orientation relationships between T4 and T3 are confirmed to be [ 001 ] T 3 / / [ 031 ] T 4 , ( 100 ) T 3 / / ( 92 6 ¯ ) T 4 , and ( 010 ) T 3 / / ( 1 2 ¯ 6 ) T 4 , respectively, based on comprehensive transmission electron microscopy (TEM) investigations. Furthermore, such dual-phase nanofibers exhibit the onset potential and half-wave potential of 0.90 V and 0.75 V as the ORR electrocatalysts in alkaline media, respectively, which illustrates the excellent ORR catalytic performance. The rotating ring-disk electrode (RRDE) experiment confirmed the electron transfer number of 3.0 for such catalysts, which indicates a mixture of two electron and four electron transfer reaction pathways. Moreover, the methanol tolerance and cycling stability of the catalysts are also investigated accordingly.
| S-EPMC7412102 | biostudies-literature
Project description:Single transition metal (TM) atoms such as Fe, Co and Ni occupying a carbon divacancy in tetragonal graphene (TG) and bonded with four nitrogen atoms (TM@N4 TG) as electrocatalysts are investigated by means of first-principles calculations. To consider the effect of solvent species on the local configuration of the active single metal, a thermodynamical full-landscape searching (TFLS) scheme is employed. The calculated thermodynamic overpotentials (ηtd ) from our TFLS indicate that Co@N4 TG displays high catalytic activity toward both oxygen evolution reaction (OER) and reduction reaction (ORR), with ηtd OER and ηtd ORR as 0.397 and 0.357 V, respectively. Its OER potential cannot be captured if only one four electron reaction loop (FERL) is considered. The actual active pathways do not always turn out to be the reactions starting from the bare site. Our findings demonstrate that TG is a promising support and TM confined TD can be used to design effective and cheap multifunctional electrocatalysts.
| S-EPMC8248917 | biostudies-literature
Project description:Synthesis of electrocatalysts for oxygen reduction reaction (ORR) with not only prominent electrocatalytic performance but also a low amount of Pt is the urgent challenge in the popularization of fuel cells. In this work, through a facile synthetic strategy of spray dehydration on a solid surface and annealing process, we demonstrate the first manufacture of quaternary structurally ordered PtM3 (M = transition metal) intermetallic nanoparticles (NPs), Pt(Fe, Co, Ni)3, in order to lower the content of Pt. The atomic contents of Pt, Fe, Co, and Ni are equal and the chemical structure of Pt(Fe, Co, Ni)3 is a cubic L12-ordered structure. L12-Pt(Fe, Co, Ni)3/C electrocatalysts exhibit enhanced electrocatalytic performance toward ORR with mass activity (MA) 6.6 times higher than the commercial Pt/C and a minimal loss of 17% in MA and 1.5% loss in specific activity (SA) after 10 000 potential cycles at 0.9 V. Furthermore, the stability behavior is confirmed to be attributed to the coaction of particle sizes and the ordering effect. Compared with traditional Pt-based electrocatalysts in the stoichiometric forms of Pt3M and PtM, L12-Pt(Fe, Co, Ni)3 intermetallic NPs exhibit excellent performance and higher cost effectiveness. Moreover, this work also proposes a facile and effective synthetic strategy for manufacturing multicomponent Pt-based electrocatalysts for ORR.
| S-EPMC6822218 | biostudies-literature
Project description:The development of highly active, cheap and robust oxygen reduction reaction (ORR) electrocatalysts to replace precious metal platinum is extremely urgent and challenging for renewable energy devices. Herein we report a novel, green and especially facile hydrogel strategy to construct N and B co-doped nanocarbon embedded with Co-based nanoparticles as an efficient non-precious ORR catalyst. The agarose hydrogel provides a general host matrix to achieve a homogeneous distribution of key precursory components including cobalt (II) acetate and buffer salts, which, upon freeze-drying and carbonization, produces the highly active ORR catalyst. The gel buffer containing Tris base, boric acid and ethylenediaminetetraacetic acid, commonly adopted for pH and ionic strength control, plays distinctively different roles here. These include a green precursor for N- and B-doping, a salt porogen and a Co(2+) chelating agent, all contributing to the excellent ORR activity. This hydrogel-based process is potentially generalizable for many other catalytic materials.
| S-EPMC4486930 | biostudies-literature
Project description:The rational design of economical and high-performance nanocatalysts to substitute Pt for the oxygen reduction reaction (ORR) is extremely desirable for the advancement of sustainable energy-conversion devices. Isolated single atom (ISA) catalysts have sparked tremendous interests in electrocatalysis due to their maximized atom utilization efficiency. Nevertheless, the fabrication of ISA catalysts remains a grand challenge. Here, a template-assisted approach is demonstrated to synthesize isolated Fe single atomic sites anchoring on graphene hollow nanospheres (denoted as Fe ISAs/GHSs) by using Fe phthalocyanine (FePc) as Fe precursor. The rigid planar macrocycle structure of FePc molecules and the steric-hindrance effect of graphene nanospheres are responsible for the dispersion of Fe-N x species at an atomic level. The combination of atomically dispersed Fe active sites and highly steady hollow substrate affords the Fe ISAs/GHSs outstanding ORR performance with enhanced activity, long-term stability, and better tolerance to methanol, SO2, and NO x in alkaline medium, outperforming the state-of-the-art commercial Pt/C catalyst. This work highlights the great promises of cost-effective Fe-based ISA catalysts in electrocatalysis and provides a versatile strategy for the synthesis of other single metal atom catalysts with superior performance for diverse applications.
| S-EPMC6343057 | biostudies-literature
Project description:Oxygen reduction reaction (ORR) plays significant roles in electrochemical energy storage and conversion systems as well as clean synthesis of fine chemicals. However, the ORR process shows sluggish kinetics and requires platinum-group noble metal catalysts to accelerate the reaction. The high cost, rare reservation, and unsatisfied durability significantly impede large-scale commercialization of platinum-based catalysts. Single-atom electrocatalysts (SAECs) featuring with well-defined structure, high intrinsic activity, and maximum atom efficiency have emerged as a novel field in electrocatalytic science since it is promising to substitute expensive platinum-group noble metal catalysts. However, finely fabricating SAECs with uniform and highly dense active sites, fully maximizing the utilization efficiency of active sites, and maintaining the atomically isolated sites as single-atom centers under harsh electrocatalytic conditions remain urgent challenges. In this review, we summarized recent advances of SAECs in synthesis, characterization, oxygen reduction reaction (ORR) performance, and applications in ORR-related H2O2 production, metal-air batteries, and low-temperature fuel cells. Relevant progress on tailoring the coordination structure of isolated metal centers by doping other metals or ligands, enriching the concentration of single-atom sites by increasing metal loadings, and engineering the porosity and electronic structure of the support by optimizing the mass and electron transport are also reviewed. Moreover, general strategies to synthesize SAECs with high metal loadings on practical scale are highlighted, the deep learning algorithm for rational design of SAECs is introduced, and theoretical understanding of active-site structures of SAECs is discussed as well. Perspectives on future directions and remaining challenges of SAECs are presented.
| S-EPMC7443255 | biostudies-literature