scholarly journals Spray-Pyrolytic Tunable Structures of Mn Oxides-Based Composites for Electrocatalytic Activity Improvement in Oxygen Reduction

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 22
Author(s):  
Miroslava Varničić ◽  
Miroslav M. Pavlović ◽  
Sanja Eraković Pantović ◽  
Marija Mihailović ◽  
Marijana R. Pantović Pavlović ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Hybrid Materials ◽  
Electrocatalytic Activity ◽  
Ultrasonic Spray Pyrolysis ◽  
Linear Sweep Voltammetry ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Single Step ◽  
Rotating Disk Electrode ◽  
Alkaline Media

Hybrid nanomaterials based on manganese, cobalt, and lanthanum oxides of different morphology and phase compositions were prepared using a facile single-step ultrasonic spray pyrolysis (USP) process and tested as electrocatalysts for oxygen reduction reaction (ORR). The structural and morphological characterizations were completed by XRD and SEM-EDS. Electrochemical performance was characterized by cyclic voltammetry and linear sweep voltammetry in a rotating disk electrode assembly. All synthesized materials were found electrocatalytically active for ORR in alkaline media. Two different manganese oxide states were incorporated into a Co3O4 matrix, δ-MnO2 at 500 and 600 °C and manganese (II,III) oxide-Mn3O4 at 800 °C. The difference in crystalline structure revealed flower-like nanosheets for birnessite-MnO2 and well-defined spherical nanoparticles for material based on Mn3O4. Electrochemical responses indicate that the ORR mechanism follows a preceding step of MnO2 reduction to MnOOH. The calculated number of electrons exchanged for the hybrid materials demonstrate a four-electron oxygen reduction pathway and high electrocatalytic activity towards ORR. The comparison of molar catalytic activities points out the importance of the composition and that the synergy of Co and Mn is superior to Co3O4/La2O3 and pristine Mn oxide. The results reveal that synthesized hybrid materials are promising electrocatalysts for ORR.

Metal molybdate nanorods as non-precious electrocatalysts for the oxygen reduction

2015 ◽  
Vol 08 (03) ◽  
pp. 1540005 ◽  
Author(s):  
Tian Wu ◽  
Lieyu Zhang
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction ◽  
Large Scale ◽  
Linear Sweep Voltammetry ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Alkaline Media ◽  
One Pot ◽  
Metal Molybdate

Development of non-precious electrocatalysts with applicable electrocatalytic activity towards the oxygen reduction reaction (ORR) is important to fulfill broad-based and large-scale applications of metal/air batteries and fuel cells. Herein, nickel and cobalt molybdates with uniform nanorod morphology are synthesized using a facile one-pot hydrothermal method. The ORR activity of the prepared metal molybdate nanorods in alkaline media are investigated by using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperomety in rotating disk electrode (RDE) techniques. The present study suggests that the prepared metal molybdate nanorods exhibit applicable electrocatalytic activities towards the ORR in alkaline media, promising the applications as non-precious cathode in fuel cells and metal–air batteries.

Ethanol: Tolerant Oxygen Reduction Reaction Catalysts in Alkaline Media

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
Chakkrapong Chaiburi ◽  
Bernd Cermenek ◽  
Birgit Elvira Pichler ◽  
Christoph Grimmer ◽  
Viktor Hacker
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
State Of The Art ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Alkaline Media ◽  
Direct Ethanol Fuel Cells ◽  
X Ray ◽  
Transmission Electron

This paper describes electrocatalysts for the oxygen reduction reaction (ORR) in alkaline direct ethanol fuel cells (ADEFCs), using the non-noble metal electrocatalyst Ag/C, MnO2/C and AgMnO2/C. These electrocatalysts showed tolerance toward ethanol in alkaline media and therefore resistance to ethanol crossover in ADEFCs. Transmission electron microscopy, X-ray spectroscopy (EDX), cyclic voltammetry, and rotating disk electrode (RDE) were employed to determine the morphology, composition, and electrochemical activity of the catalysts. The herein presented results confirm that the AgMnO2/C electrocatalyst significantly outperforms the state-of-the art ORR catalyst platinum.

Mn-Co oxide/PEDOT as a bifunctional electrocatalyst for oxygen evolution/reduction reactions

2015 ◽  
Vol 1777 ◽  
pp. 1-6 ◽  
Author(s):  
Elaheh Davari ◽  
Douglas G. Ivey
Keyword(s):  
Oxygen Reduction ◽  
Oxygen Evolution ◽  
Linear Sweep Voltammetry ◽  
Microstructural Characterization ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Bifunctional Electrocatalyst ◽  
Bifunctional Electrocatalysts ◽  
Anodic Electrodeposition

ABSTRACTBifunctional electrocatalysts, which facilitate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), are vital components in advanced metal-air batteries. Results are presented for carbon-free, nanocrystalline, rod-like, Mn-Co oxide/PEDOT bifunctional electrocatalysts, prepared by template-free sequential anodic electrodeposition. Electrochemical characterization of synthesized electrocatalysts, with and without a conducting polymer (PEDOT) coating, was performed using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). In addition, microstructural characterization was conducted using SEM, TEM, STEM and XPS. Mn-Co oxide/PEDOT showed improved ORR/OER performance relative to Mn-Co oxide and PEDOT. On the basis of rotating disk electrode (RDE) experiments, Mn-Co oxide/PEDOT displayed the desired 4-electron transfer oxygen reduction pathway. Comparable ORR activity and superior OER activity relative to commercial Pt/C were observed.

Synthesis, characterization and electrocatalytic properties of bimetallic sulfides CoS/MnS/N-C for oxygen reduction in alkaline media

2021 ◽  
Vol 25 (04) ◽  
pp. 336-342
Author(s):  
Ningchao Liu ◽  
Laihai Huang ◽  
Jian Rong ◽  
Zhaoli Xue ◽  
Zhongping Ou ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Rotating Disk ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Alkaline Media ◽  
Alkaline Condition ◽  
Zeolitic Imidazolate Framework ◽  
Electrocatalytic Properties ◽  
Bimetallic Sulfide

Synthesis, characterization and oxygen reduction reaction (ORR) catalytic properties of bimetallic sulfides CoS/MnS/N-C catalyst was discussed. The catalyst was derived from a typical Co based zeolitic imidazolate framework (ZIF-67) and manganese aminoporphyrin. 5,15-Bis(4-aminophenyl)-10,20-bis(4-bromophenyl) porphyrin manganese oxoacetate loaded with ZIF-67 forms a porphyrin loaded ZIF-67. This product was then calcined at 800ˆ∘C and vulcanized with thioacetamide to obtain the bimetallic sulfide product CoS/MnS/N-C. The structure of CoS/MnS/N-C was further characterized by XRD, XPS, FESEM and HRTEM spectra which indicated a novel porous and hollow sphere structure. The electrocatalytic properties of the bimetallic material as well as its parent porphyrin and ZIF-67 were also compared in alkaline condition (0.1 M KOH) with a rotating disk electrode. The prepared catalyst CoS/MnS/N-C exhibits a higher catalytic performance than its precursors (PorMnOAc, ZIF-67 and PorMnOAc loaded ZIF-67) with almost four electron transfers under this condition.

PtNi and CoNi Film Electrocatalysts Prepared by MOCVD for the Oxygen Reduction Reaction in Alkaline Media

2011 ◽  
Vol 14 (2) ◽  
pp. 81-85 ◽  
Author(s):  
M. A. Garcia-Contreras ◽  
S. M. Fernandez-Valverde ◽  
J. R. Vargas-Garcia
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Chemical Vapour ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Alkaline Media ◽  
Organic Chemical ◽  
Experimental Conditions ◽  
X Ray

CoNi and PtNi film electrocatalysts were prepared by Metal-Organic Chemical Vapour Deposition (MOCVD) and their electrocatalytic activity for the oxygen reduction reaction (ORR) in 0.5 M KOH was investigated by cyclic voltammetry and Rotating Disk Electrode techniques. Experiments included working electrodes of Co, Ni and Pt prepared also by MOCVD for comparison. The film electrocatalysts were characterized by X-ray diffraction, Scanning Electronic Microscopy and Energy dispersive X-ray analysis. Films thickness was about 200-250 nm and nanocrystallites were found in the range of 12 to 30 nm. In the same experimental conditions, the overpotential for the ORR at a current density of 1 mA cm-2 for PtNi film was 120 mV lower than the overpotential of Pt film electrocatalyst, and an enhanced activity was observed on PtNi with respect to Pt. The electrochemical response for the oxygen reduction reaction on CoNi film was higher than those of elemental Ni and Co films obtained by MOCVD. A good stability was obtained in a chronoamperometry test for the PtNi electrode, only affected by oxygen flow variations.

scholarly journals Synthesis and electrocatalytic activity towards oxygen reduction reaction of gold-nanostars

2018 ◽  
Vol 18 (44) ◽  
pp. 36-40
Author(s):  
Oyunbileg G ◽  
Batnyagt G ◽  
Enkhsaruul B ◽  
T Takeguchi
Keyword(s):  
Electron Microscope ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Electrocatalytic Activity ◽  
Electrical Energy ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Alkaline Electrolyte ◽  
Study Results

The oxygen reduction reaction (ORR) is a characteristic reaction which determines the performance of fuel cells which convert a chemical energy into an electrical energy. Aims of this study are to synthesize Au-based nanostars (AuNSs) and determine their preliminary electro-catalytic activities towards ORR by a rotating-disk electrode method in alkaline electrolyte. The images obtained from a scanning electron microscope (SEM) and a transmission electron microscope (TEM) analyses confirm the formation of the star-shaped nanoparticles. Among the investigated nanostar catalysts, an AuNS5 with smaller size and a few branches showed the higher electrocatalytic activity towards ORR than other catalysts with a bigger size. In addition, the electron numbers transferred for all the catalysts are approximately two. The present study results infer that the size of the Au-based nanostars may influence greatly on their catalytic activity. The present study results show that the further improvement is needed for Au-based nanostar catalysts towards the ORR reaction.

scholarly journals Accurate Assessment of the Oxygen Reduction Electrocatalytic Activity of Mn/Polypyrrole Nanocomposites Based on Rotating Disk Electrode Measurements, Complemented with Multitechnique Structural Characterizations

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Patrizia Bocchetta ◽  
Carolina Ramírez Sánchez ◽  
Antonietta Taurino ◽  
Benedetto Bozzini
Keyword(s):  
Oxygen Reduction ◽  
Electrocatalytic Activity ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Activity Measurement ◽  
Disk Electrode ◽  
Atomic Force ◽  
Structural Characterizations

This paper reports on the quantitative assessment of the oxygen reduction reaction (ORR) electrocatalytic activity of electrodeposited Mn/polypyrrole (PPy) nanocomposites for alkaline aqueous solutions, based on the Rotating Disk Electrode (RDE) method and accompanied by structural characterizations relevant to the establishment of structure-function relationships. The characterization of Mn/PPy films is addressed to the following: (i) morphology, as assessed by Field-Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscope (AFM); (ii) local electrical conductivity, as measured by Scanning Probe Microscopy (SPM); and (iii) molecular structure, accessed by Raman Spectroscopy; these data provide the background against which the electrocatalytic activity can be rationalised. For comparison, the properties of Mn/PPy are gauged against those of graphite, PPy, and polycrystalline-Pt (poly-Pt). Due to the literature lack of accepted protocols for precise catalytic activity measurement at poly-Pt electrode in alkaline solution using the RDE methodology, we have also worked on the obtainment of an intralaboratory benchmark by evidencing some of the time-consuming parameters which drastically affect the reliability and repeatability of the measurement.

scholarly journals Oxygen reduction on silver catalysts electrodeposited on various nanocarbon supports

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Jonas Mart Linge ◽  
Heiki Erikson ◽  
Maido Merisalu ◽  
Väino Sammelselg ◽  
Kaido Tammeveski
Keyword(s):  
Oxygen Reduction ◽  
Substrate Surface ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Alkaline Media ◽  
Silver Catalysts ◽  
Half Wave ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

AbstractIn this work, Ag particles were electrodeposited onto nitrogen-doped graphene oxide, graphene, multi-walled carbon nanotube (MWCNT), and Vulcan carbon XC-72R supports by varying the upper potential limit. The surface morphology of the resulting Ag-based catalysts was examined by scanning electron microscopy. The electrochemical oxygen reduction reaction (ORR) was tested in alkaline media employing the rotating disk electrode method. The variation of the upper potential limit influenced the size of silver nanoparticles and their number density on the substrate surface. All the Ag-based electrocatalysts studied in this work showed remarkable ORR activity in terms of half-wave potentials. The ORR results combined with hydrogen peroxide reduction results prove that all Ag catalysts tested are suitable for both reactions. Ag/NGO2 catalyst possesses the highest mass activity for ORR, which indicates a relationship between the Ag loading and electrocatalytic activity. The electroreduction of oxygen on all the electrodeposited silver catalysts follows a four-electron pathway in alkaline environment. These materials are promising alternatives for Pt/C catalyst to be used as alkaline membrane fuel cell cathodes.

scholarly journals PtCoNb2O5/graphene as electrocatalyst towards oxygen reduction reaction in alkaline and acidic media

Chemija ◽  
2018 ◽  
Vol 29 (1) ◽  
Author(s):  
Virginija Kepenienė ◽  
Raminta Stagniūnaitė ◽  
Loreta Tamašauskaitė-Tamašiūnaitė ◽  
Vidas Pakštas ◽  
Eugenijus Norkus
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Cobalt Catalyst ◽  
Linear Sweep Voltammetry ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Acidic Media ◽  
Acidic Solutions ◽  
Supported Platinum

The aim of the study was to prepare and to investigate the catalytic activity of the Nb2O5/graphene-supported platinum–cobalt catalyst for the oxygen reduction reaction (ORR) in alkaline and acidic media. Electrocatalytic properties of the prepared catalyst towards the oxygen reduction reaction were characterized by using cyclic voltammetry (CV) and rotating disk electrode (RDE) linear sweep voltammetry (LSV). It has been found that the PtCoNb2O5/graphene catalyst shows more positive onset potentials, as well as higher current in the mixed-kineticdiffusion region towards the oxygen reduction reaction in both alkaline and acidic solutions as compared with those for the bare Pt/GR catalyst.

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