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 Eco-Friendly Nitrogen-Doped Graphene Preparation and Design for the Oxygen Reduction Reaction

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3858
Author(s):  
Monica Dan ◽  
Adriana Vulcu ◽  
Sebastian A. Porav ◽  
Cristian Leostean ◽  
Gheorghe Borodi ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Machine Learning Algorithms ◽  
Rotating Disk Electrode ◽  
X Ray ◽  
Synthesis Conditions ◽  
Characterization Techniques ◽  
Doped Graphene

Four N-doped graphene materials with a nitrogen content ranging from 8.34 to 13.1 wt.% are prepared by the ball milling method. This method represents an eco-friendly mechanochemical process that can be easily adapted for industrial-scale productivity and allows both the exfoliation of graphite and the synthesis of large quantities of functionalized graphene. These materials are characterized by transmission and scanning electron microscopy, thermogravimetry measurements, X-ray powder diffraction, X-ray photoelectron and Raman spectroscopy, and then, are tested towards the oxygen reduction reaction by cyclic voltammetry and rotating disk electrode methods. Their responses towards ORR are analysed in correlation with their properties and use for the best ORR catalyst identification. However, even though the mechanochemical procedure and the characterization techniques are clean and green methods (i.e., water is the only solvent used for these syntheses and investigations), they are time consuming and, generally, a low number of materials can be prepared, characterized and tested. In order to eliminate some of these limitations, the use of regression learner and reverse engineering methods are proposed for facilitating the optimization of the synthesis conditions and the materials’ design. Thus, the machine learning algorithms are applied to data containing the synthesis parameters, the results obtained from different characterization techniques and the materials response towards ORR to quickly provide predictions that allow the best synthesis conditions or the best electrocatalysts’ identification.

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.

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 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.

Low-cost sonochemical synthesis of nitrogen-doped graphene metal-free electrocatalyst for the oxygen reduction reaction in alkaline media

2017 ◽  
Vol 42 (51) ◽  
pp. 30330-30338 ◽  
Author(s):  
I.L. Alonso-Lemus ◽  
M.Z. Figueroa-Torres ◽  
A.B. García-Hernández ◽  
B. Escobar-Morales ◽  
F.J. Rodríguez-Varela ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Low Cost ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Sonochemical Synthesis ◽  
Nitrogen Doped ◽  
Metal Free ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene
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