scholarly journals Proposal of a Facile Method to Fabricate a Multi-Dope Multiwall Carbon Nanotube as a Metal-Free Electrocatalyst for the Oxygen Reduction Reaction

2022 ◽  
Vol 14 (2) ◽  
pp. 965
Author(s):  
Sara Bakhtavar ◽  
Mehdi Mehrpooya ◽  
Mahboobeh Manoochehri ◽  
Mehrnoosh Karimkhani
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Electron Transfer ◽  
Low Temperature ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Active Sites ◽  
Reduction Reaction ◽  
Multiwall Carbon Nanotube ◽  
Multiwall Carbon

In this study, a one-pot, low-temperature synthesis method is considered for the fabrication of heteroatom dope multiwall carbon nanotubes (MWCNT). Doped MWCNT is utilized as an effective electrocatalyst for oxygen reduction reaction (ORR). Single, double, and triple doping of boron, nitrogen and sulfur elements are utilized as the dopants. A reflux system with temperature of 180 °C is implemented in the doping procedure. Actually, unlike the previous studies in which doping on the carbon structures was performed using a furnace at temperatures above 700 °C, in this green and sustainable method, the triple doping on MWCNT is conducted at atmospheric pressure and low temperature. The morphology and structure of the fabricated catalysts were evaluated by Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Raman spectroscopy. According to the results, the nanoparticles were encapsulated in the carbon nanotubes. Aggregated clusters of the sulfur in the case of S-MWCNT are considerable. Cyclic voltammetry (CV), rotating disk electrode, linear sweep voltammetry (LSV), and chronoamperometry electrochemical tests are employed for assessing the oxygen reduction activity of the catalysts. The results illustrate that by using this doping method, the onset potential shifts to positive values towards the oxidized MWCNT. It can be deduced that by doping the N, B, and S atoms on MWCNTs, the defects in the CNT structure, which serve as active sites for ORR application, increase. The N/S/B-doped graphitic layers have a more rapid electron transfer rate at the electrode/electrolyte interface. Thus, this can improve the electrochemistry performance and electron transfer of the MWCNTs. The best performance and electrochemical activity belonged to the NB-MWCNT catalyst (−0.122 V vs. Ag/AgCl). Also, based on the results gained from the Koutecky–Levich (KL) plot, it can be said that the ORR takes place through the 4 e− pathway.

scholarly journals Synergistic Effects of Active Sites’ Nature and Hydrophilicity on the Oxygen Reduction Reaction Activity of Pt-Free Catalysts

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 643 ◽  
Author(s):  
Mariangela Longhi ◽  
Camilla Cova ◽  
Eleonora Pargoletti ◽  
Mauro Coduri ◽  
Saveria Santangelo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Carbon Nanostructures ◽  
Active Sites ◽  
Active Material ◽  
Reduction Reaction ◽  
X Ray

This work highlights the importance of the hydrophilicity of a catalyst’s active sites on an oxygen reduction reaction (ORR) through an electrochemical and physico-chemical study on catalysts based on nitrogen-modified carbon doped with different metals (Fe, Cu, and a mixture of them). BET, X-ray Powder Diffraction (XRPD), micro-Raman, X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and hydrophilicity measurements were performed. All synthesized catalysts are characterized not only by a porous structure, with the porosity distribution centered in the mesoporosity range, but also by the presence of carbon nanostructures. In iron-doped materials, these nanostructures are bamboo-like structures typical of nitrogen carbon nanotubes, which are better organized, in a larger amount, and longer than those in the copper-doped material. Electrochemical ORR results highlight that the presence of iron and nitrogen carbon nanotubes is beneficial to the electroactivity of these materials, but also that the hydrophilicity of the active site is an important parameter affecting electrocatalytic properties. The most active material contains a mixture of Fe and Cu.

A co-pyrolysis route to synthesize nitrogen doped multiwall carbon nanotubes for oxygen reduction reaction

Carbon ◽  
2014 ◽  
Vol 68 ◽  
pp. 232-239 ◽  
Author(s):  
Yongxia Wang ◽  
Xiangzhi Cui ◽  
Yongsheng Li ◽  
Lisong Chen ◽  
Hangrong Chen ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Multiwall Carbon Nanotubes ◽  
Reduction Reaction ◽  
Nitrogen Doped ◽  
Multiwall Carbon

Nitrogen-Doped Carbon Nanotubes and Graphene Nanohybrid for Oxygen Reduction Reaction in Acidic, Alkaline and Neutral Solutions

2015 ◽  
Vol 30 ◽  
pp. 50-58 ◽  
Author(s):  
Ji Yue Liu ◽  
Zan Wang ◽  
Jing Yan Chen ◽  
Xin Wang
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Chemical Vapor ◽  
Electrochemical Measurement ◽  
Reduction Reaction ◽  
Neutral Medium ◽  
Nitrogen Doped ◽  
Nitrogen Doped Carbon

Nitrogen-doped carbon nanotubes (N-CNTs) have beenprepared on FeNi catalyst by plasma-enhanced chemical vapor deposition in amixture of N2, O2, and CH4. On the opened topof CNT, multi-layer graphene grown self-assembly was observed by transmissionelectron microscopy and high resolution transmission electron microscopy. Thenanohybrid film analyzed by scanning electron microscopy exhibited a porous and3D morphology and pyridinic and graphitic nitrogen structure confirmed by x-rayphotoelectron spectroscopy. Electrochemical measurement indicated that the filmfacilitated about three-electron transferpathway for oxygen reduction reaction in neutral medium and two-electronreductions in both alkaline and acidic solutions.

Creation of oxygen reduction reaction active sites on titanium oxynitride without increasing the nitrogen doping level

2018 ◽  
Vol 20 (23) ◽  
pp. 15613-15617 ◽  
Author(s):  
Mitsuharu Chisaka
Keyword(s):  
Low Temperature ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Doping Level ◽  
Active Sites ◽  
Nitrogen Doping ◽  
Reduction Reaction ◽  
Low Temperature Annealing

Active sites were created on ORR-active titanium oxynitride by low-temperature annealing without changing the nitrogen doping level to determine their origin.

scholarly journals Multi-Walled Carbon Nanotubes Supported Pd(II) Complexes: A Supramolecular Approach towards Single-Ion Oxygen Reduction Reaction Catalysts

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5539
Author(s):  
Matteo Savastano ◽  
Maurizio Passaponti ◽  
Walter Giurlani ◽  
Leonardo Lari ◽  
Antonio Bianchi ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Platinum Group Metal ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
Disk Electrode ◽  
Supported Pd

Lowering the platinum group metal content of oxygen reduction reaction catalysts is among the most prevalent research focuses in the field. This target is herein approached through supported Pd(II) complexes. Starting from a commercial macrocycle, a new ligand is synthesized, its solution behavior and binding properties briefly explored (potentiometry, UV-Vis) and then used to prepare a new catalyst. A supramolecular approach is used in order to obtain homogeneous decoration of carbon nanotubes surfaces, fostering novel possibilities to access single-ion active sites. The novel catalyst is characterized through X-ray photoelectron spectroscopy and scanning transmission electron microscopy and its promising oxygen reduction reaction performance is evaluated via rotating ring-disk electrode and rotating disk electrode in half-cell studies.

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