scholarly journals REACTION OF OXYGEN REDUCTION ON THE SURFACE OF AU ON TI WITH OXIDEFORMED POTENTIODYNAMICALLY BEFORE AND AFTER THE DEPOSITION OF AU

Anales AFA ◽  
2021 ◽  
Vol 32 (1) ◽  
pp. 7-14
Author(s):  
E. N. Díaz ◽  
◽  
F. A. Filippin ◽  
A. S. Fuentes ◽  
H. J. Fasoli ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Oxygen Reduction ◽  
Electrochemical Behavior ◽  
Reduction Reaction ◽  
Electrocatalytic Reduction ◽  
Onset Potential ◽  
Composite Layers ◽  
Before And After ◽  
High Overpotentials ◽  
Current Densities

One of the most important reactions for electrochemical science and technology is the electrocatalytic reduction ofoxygen. It is particularly relevant in fuel cells because it is slow to react and requires high overpotentials. This workaims to study electrodes with deposits of Au on Ti obtained by electrodeposition. The substrates have undergone po-tentiodynamic growths of oxides before deposition for some electrodes and after deposition for other electrodes understudy, at different final potentials. Both procedures resulted in the formation of a composite Au layer on the Ti surface.The electrochemical behavior of these composite layers was examined in a 0.01 M HClO4solution, both oxygen-freeand oxygen-saturated, and compared with the behavior of Ti as a target, using the cyclic voltammetry technique. In thepotential region of the oxygen reduction reaction (RRO), the Au layer on the Ti obtained by first performing the Audeposition and then the growth of the anode oxide showed a better response, not only in the onset potential of the RRO,but also in the current densities. In all cases the voltammetry curves of the Au and TiO2 composite layers were similarto those shown by the Au polycrystalline.

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

scholarly journals Superior FexN electrocatalyst derived from 1,1′-diacetylferrocene for oxygen reduction reaction in alkaline and acidic media

2020 ◽  
Vol 9 (1) ◽  
pp. 843-852
Author(s):  
Hunan Jiang ◽  
Jinyang Li ◽  
Mengni Liang ◽  
Hanpeng Deng ◽  
Zuowan Zhou
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Current Density ◽  
Active Sites ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Acidic Media ◽  
Onset Potential ◽  
Acidic And Alkaline Media ◽  
The Stability

AbstractAlthough Fe–N/C catalysts have received increasing attention in recent years for oxygen reduction reaction (ORR), it is still challenging to precisely control the active sites during the preparation. Herein, we report FexN@RGO catalysts with the size of 2–6 nm derived from the pyrolysis of graphene oxide and 1,1′-diacetylferrocene as C and Fe precursors under the NH3/Ar atmosphere as N source. The 1,1′-diacetylferrocene transforms to Fe3O4 at 600°C and transforms to Fe3N and Fe2N at 700°C and 800°C, respectively. The as-prepared FexN@RGO catalysts exhibited superior electrocatalytic activities in acidic and alkaline media compared with the commercial 10% Pt/C, in terms of electrochemical surface area, onset potential, half-wave potential, number of electrons transferred, kinetic current density, and exchange current density. In addition, the stability of FGN-8 also outperformed commercial 10% Pt/C after 10000 cycles, which demonstrates the as-prepared FexN@RGO as durable and active ORR catalysts in acidic media.

Methanol-Tolerant Oxygen Reduction Reaction at Pt–Pd/C Alloy Nanocatalysts

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
A. Mary Remona ◽  
K. L. N. Phani
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Methanol Tolerance ◽  
Pd Catalysts ◽  
Onset Potential ◽  
Direct Methanol ◽  
Methanol Tolerant

Carbon-supported platinum and Pt–Pd alloy electrocatalysts with different Pt/Pd atomic ratios were synthesized by a microemulsion method at room temperature (metal loading is 10 wt %). The Pt–Pd/C bimetallic catalysts showed a single-phase fcc structure and the mean particle size of Pt–Pd/C catalysts was found to be lower than that of Pt/C. The methanol-tolerant studies of the catalysts were carried out by activity evaluation of oxygen reduction reaction (ORR) on Pt–Pd catalysts using a rotating disk electrode (RDE). The studies indicated that the order of methanol tolerance was found to be PtPd3/C>PtPd/C>Pt3Pd/C. The oxygen reduction activities of all Pt–Pd/C were considerably larger than that of Pt/C with respect to onset and overpotential values. The Pd-loaded catalysts shift the onset potential of ORR by 125 mVMSE, 53 mVMSE, and 41 mVMSE to less cathodic potentials for Pt3Pd/C, PtPd/C, and PtPd3/C, respectively, with reference to Pt/C and the Pt3Pd/C catalyst showed greater shift in the onset value than the other PtPd catalysts reported in literature. Moreover, the Pt–Pd/C catalysts exhibited much higher methanol tolerance during ORR than the Pt/C, assessing that these catalysts may function as a methanol-tolerant cathode catalysts in a direct methanol fuel cell.

scholarly journals Atomically Dispersed Fe-N4 Modified with Precisely Located S for Highly Efficient Oxygen Reduction

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yin Jia ◽  
Xuya Xiong ◽  
Danni Wang ◽  
Xinxuan Duan ◽  
Kai Sun ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Density Functional ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Edge Structure ◽  
Onset Potential ◽  
Local Environments ◽  
Half Wave ◽  
Reaction Performance ◽  
Specific Configuration

AbstractImmobilizing metal atoms by multiple nitrogen atoms has triggered exceptional catalytic activity toward many critical electrochemical reactions due to their merits of highly unsaturated coordination and strong metal-substrate interaction. Herein, atomically dispersed Fe-NC material with precise sulfur modification to Fe periphery (termed as Fe-NSC) was synthesized, X-ray absorption near edge structure analysis confirmed the central Fe atom being stabilized in a specific configuration of Fe(N3)(N–C–S). By enabling precisely localized S doping, the electronic structure of Fe-N4 moiety could be mediated, leading to the beneficial adjustment of absorption/desorption properties of reactant/intermediate on Fe center. Density functional theory simulation suggested that more negative charge density would be localized over Fe-N4 moiety after S doping, allowing weakened binding capability to *OH intermediates and faster charge transfer from Fe center to O species. Electrochemical measurements revealed that the Fe-NSC sample exhibited significantly enhanced oxygen reduction reaction performance compared to the S-free Fe-NC material (termed as Fe-NC), showing an excellent onset potential of 1.09 V and half-wave potential of 0.92 V in 0.1 M KOH. Our work may enlighten relevant studies regarding to accessing improvement on the catalytic performance of atomically dispersed M-NC materials by managing precisely tuned local environments of M-Nx moiety.

Synthesis, characterization, and electrochemical behavior of a new Nd1.9Sr0.1Ni0.9Co0.1O4 ± δ material as electrocatalyst for the oxygen reduction reaction

Ionics ◽  
2019 ◽  
Vol 25 (8) ◽  
pp. 3799-3807 ◽  
Author(s):  
Sabah Amira ◽  
Mosbah Ferkhi ◽  
Mabrouk Belghobsi ◽  
Ammar Khaled ◽  
Fabrice Mauvy ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Electrochemical Behavior ◽  
Reduction Reaction

scholarly journals MOF-Derived CuPt/NC Electrocatalyst for Oxygen Reduction Reaction

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 799 ◽  
Author(s):  
Rehan Anwar ◽  
Naseem Iqbal ◽  
Saadia Hanif ◽  
Tayyaba Noor ◽  
Xuan Shi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
X Ray ◽  
Onset Potential ◽  
Orr Activity

Metal-organic frameworks (MOFs) have been at the center stage of material science in the recent past because of their structural properties and wide applications in catalysis. MOFs have also been used as hard templates for the preparation of catalysts. In this study, highly active CuPt/NC electrocatalyst was synthesized by pyrolyzing Cu-tpa MOF along with Pt precursor under flowing Ar-H2 atmosphere. The catalyst was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD). Rotating disk electrode study was performed to determine the oxygen reduction reaction (ORR) activity for CuPt/NC in 0.1 M HClO4 at different revolutions per minute (400, 800, 1200, and 1600) and it was also compared with commercial Pt/C catalyst. Further the ORR performance was evaluated by K-L plots and Tafel slope. CuPt/NC shows excellent ORR performance with onset potential of 0.9 V (vs. RHE), which is comparable with commercial Pt/C. The ORR activity of CuPt/NC is demonstrated as an efficient electrocatalyst for fuel cell.

Synergetic nanoporous Mn–Ru oxides as efficient electrocatalysts for the oxygen reduction reaction

2017 ◽  
Vol 41 (16) ◽  
pp. 8196-8202 ◽  
Author(s):  
Mohamed B. Zakaria ◽  
Toyohiro Chikyow
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Mixed Oxides ◽  
Reduction Reaction ◽  
Electrocatalytic Reduction ◽  
Similar Morphology

Nanoporous Mn–Ru mixed oxides were derived from Mn–Ru CP nanocubes with a similar morphology through annealing in air at 400 degree for effecient electrocatalytic reduction of oxygen.

High-Stability Platinum Nano-Electrocatalyst Synthesized by Cyclic Voltammetry for Oxygen Reduction Reaction

2018 ◽  
Vol 47 (12) ◽  
pp. 6995-7001 ◽  
Author(s):  
Rasol Abdullah Mirzaie ◽  
Azam Anaraki Firooz ◽  
Narges Mohammadkhani Khori
Keyword(s):  
Cyclic Voltammetry ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
High Stability ◽  
Reduction Reaction

scholarly journals Nitrogen-Doped Superporous Activated Carbons as Electrocatalysts for the Oxygen Reduction Reaction

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1346 ◽  
Author(s):  
María José Mostazo-López ◽  
David Salinas-Torres ◽  
Ramiro Ruiz-Rosas ◽  
Emilia Morallón ◽  
Diego Cazorla-Amorós
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
High Temperatures ◽  
Photoelectron Spectroscopy ◽  
Activated Carbons ◽  
Inert Atmosphere ◽  
Reduction Reaction ◽  
Treatment Temperature ◽  
Onset Potential ◽  
Nitrogen Functionalization

Nitrogen-containing superporous activated carbons were prepared by chemical polymerization of aniline and nitrogen functionalization by organic routes. The resulting N-doped carbon materials were carbonized at high temperatures (600–800 °C) in inert atmosphere. X-ray Photoelectron Spectroscopy (XPS) revealed that nitrogen amount ranges from 1 to 4 at.% and the nature of the nitrogen groups depends on the treatment temperature. All samples were assessed as electrocatalysts for the oxygen reduction reaction (ORR) in alkaline solution (0.1 M KOH) in order to understand the role of well-developed microporosity as well as the different nitrogen functionalities on the electrocatalytic performance in ORR. It was observed that nitrogen groups generated at high temperatures were highly selective towards the water formation. Among the investigated samples, polyaniline-derived activated carbon carbonized at 800 °C displayed the best performance (onset potential of 0.88 V versus RHE and an electron transfer number of 3.4), which was attributed to the highest concentration of N–C–O sites.

Palladium copper nanosponges for electrocatalytic reduction of oxygen and glucose detection

2015 ◽  
Vol 3 (18) ◽  
pp. 9675-9681 ◽  
Author(s):  
Wen-Ping Wu ◽  
Arun Prakash Periasamy ◽  
Guan-Lin Lin ◽  
Zih-Yu Shih ◽  
Huan-Tsung Chang
Keyword(s):  
Catalytic Activity ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
High Catalytic Activity ◽  
Glucose Detection ◽  
Cathode Catalyst ◽  
Electrocatalytic Reduction ◽  
One Pot

One-pot synthesized PdCu nanosponges (NSs) are separately used as a cathode catalyst for the oxygen reduction reaction in alkaline media and for enzymeless detection of glucose with high catalytic activity, stability, and durability.

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