scholarly journals Mn-Ni-Co-O Spinel Oxides towards Oxygen Reduction Reaction in Alkaline Medium: Mn0.5Ni0.5Co2O4/C Synergism and Cooperation

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1059
Author(s):  
Thabo Matthews ◽  
Tarekegn Heliso Dolla ◽  
Sandile Surprise Gwebu ◽  
Tebogo Abigail Mashola ◽  
Lihle Tshepiso Dlamini ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Surface Area ◽  
Electrocatalytic Activity ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Electrocatalytic Oxygen Reduction ◽  
Spinel Oxides ◽  
A Current

Mn-doped spinel oxides MnxNi1−xCo2O4 (x = 0, 0.3, 0.5, 0.7, and 1) were synthesized using the citric acid-assisted sol–gel method. The Mn0.5Ni0.5Co2O4 (x = 0.5) supported on carbon nanosheets, Mn0.5Ni0.5Co2O4/C, was also prepared using the same method employing NaCl and glucose as a template and carbon source, respectively, followed by pyrolysis under an inert atmosphere. The electrocatalytic oxygen reduction reaction (ORR) activity was performed in alkaline media. Cyclic voltammetry (CV) was used to investigate the oxygen reduction performance of MnxNi1−xCo2O4 (x = 0, 0.3, 0.5, 0.7, and 1), and Mn0.5Ni0.5Co2O4 was found to be the best-performing electrocatalyst. Upon supporting the Mn0.5Ni0.5Co2O4 on a carbon sheet, the electrocatalytic activity was significantly enhanced owing to its large surface area and the improved charge transfer brought about by the carbon support. Rotating disk electrode studies show that the ORR electrocatalytic activity of Mn0.5Ni0.5Co2O4/C proceeds via a four-electron pathway. Mn0.5Ni0.5Co2O4/C was found to possess E1/2(V) = 0.856, a current density of 5.54 mA cm−2, and a current loss of approximately 0.11% after 405 voltammetric scan cycles. This study suggests that the interesting electrocatalytic performance of multimetallic transition metal oxides can be further enhanced by supporting them on conductive carbon materials, which improve charge transfer and provide a more active surface area.

Glancing Angle Deposited Platinum Nanorod Arrays for Oxygen Reduction Reaction

2011 ◽  
Vol 1311 ◽  
Author(s):  
Wisam J. Khudhayer ◽  
Nancy Kariuki ◽  
Deborah Myers ◽  
Ali Shaikh ◽  
Tansel Karabacak
Keyword(s):  
Oxygen Reduction Reaction ◽  
Single Crystal ◽  
Oxygen Reduction ◽  
Surface Area ◽  
Reduction Reaction ◽  
Active Surface Area ◽  
Nanorod Arrays ◽  
Electrocatalytic Oxygen Reduction ◽  
Glancing Angle ◽  
Orr Activity

ABSTRACTIn this work, we investigated the electrocatalytic oxygen reduction reaction (ORR) activity of vertically aligned, single-layer, carbon-free, and single crystal Pt nanorod arrays utilizing cyclic voltammetry (CV) and rotating-disk electrode (RDE) techniques. A glancing angle deposition (GLAD) technique was used to fabricate 200 nm long Pt nanorods, which corresponds to Pt loading of 0.16 mg/cm2, on glassy carbon (GC) electrode at a glancing angle of 85° as measured from the substrate normal. An electrode comprised of conventional carbon-supported Pt nanoparticles (Pt/C) was also prepared for comparison with the electrocatalytic ORR activity and stability of Pt nanorods. CV results showed that the Pt nanorod electrocatalyst exhibits a more positive oxide reduction peak potential compared to Pt/C, indicating that GLAD Pt nanorods are less oxophilic. In addition, a series of CV cycles in acidic electrolyte revealed that Pt nanorods are significantly more stable against electrochemically-active surface area loss than Pt/C. Moreover, room temperature RDE results demonstrated that GLAD Pt nanorods exhibit higher area-specific ORR activity than Pt/C. The enhanced electrocatalytic ORR activity of Pt nanorods is attributed to their larger crystallite size, single-crystal property, and the dominance of (110) crystal planes on the large surface area nanorods sidewalls, which has been found to be the most active plane for ORR. However, the Pt nanorods showed lower mass specific activity than the Pt/C electrocatalyst due to the large diameter of the Pt nanorods.

2D Layered non-precious metal mesoporous electrocatalysts for enhanced oxygen reduction reaction

2017 ◽  
Vol 5 (10) ◽  
pp. 4868-4878 ◽  
Author(s):  
Lili Huo ◽  
Baocang Liu ◽  
Geng Zhang ◽  
Rui Si ◽  
Jian Liu ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Specific Surface ◽  
Oxygen Reduction ◽  
Electrocatalytic Activity ◽  
Precious Metal ◽  
Reduction Reaction ◽  
High Specific Surface Area ◽  
Alkaline Media ◽  
Homogeneous Distribution ◽  
Acidic And Alkaline Media

2D Layered meso-M/N-C/N-G nanocomposites with high specific surface area, homogeneous distribution of ultra-small M-N-C nanoparticles less than 5 nm, and mesopores with a size of ∼3.6 nm exhibit excellent electrocatalytic activity toward oxygen reduction reaction (ORR) in acidic and alkaline media.

Carbon Paper-Supported NiCo/C–N Catalysts Synthesized by Directly Pyrolyzing NiCo-Doped Polyaniline for Oxygen Reduction Reaction

NANO ◽  
2018 ◽  
Vol 13 (01) ◽  
pp. 1850006 ◽  
Author(s):  
Zhongliang Deng ◽  
Qingfeng Yi ◽  
Yuanyuan Zhang ◽  
Huidong Nie ◽  
Guang Li ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Current Density ◽  
Electrocatalytic Activity ◽  
Gas Diffusion ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Carbon Paper ◽  
Onset Potential ◽  
Doped Polyaniline

In this study, we report the findings that the C–N composites containing Ni and Co (Ni1Co1/C–N, Ni3Co1/C–N, Ni6Co1/C–N, Ni9Co1/C–N, Ni[Formula: see text]Co0/C–N and Ni0Co[Formula: see text]/C–N) can be produced by direct pyrolysis of the NiCo-doped polyaniline (PANI) precursors in N2 atmosphere at 800[Formula: see text]C and show efficient electroactivity for oxygen reduction reaction (ORR) in alkaline media. Distribution and compositions of the catalysts were characterized by SEM, TEM, EDS and XRD techniques. The catalysts were loaded on carbon paper to prepare gas diffusion electrodes, in which electrocatalytic activity for ORR in alkaline media was investigated by voltammetric techniques. The ORR current density on these carbon paper-supported NiCo/C–N catalysts exhibits a linear increase with the negative shift of ORR potential. The ORR onset potential is around [Formula: see text]0.2[Formula: see text]V (versus Ag/AgCl) in alkaline media. Among the prepared catalysts, the catalyst Ni6Co1/C–N presents the largest ORR current density, which is 68.5[Formula: see text]mA[Formula: see text]cm[Formula: see text]@[Formula: see text]0.8[Formula: see text]V (versus Ag/AgCl) in alkaline media. Moreover, Ni6Co1/C–N catalyst also presents good electrocatalytic activity stability for ORR.

Chemical etching of manganese oxides for electrocatalytic oxygen reduction reaction

2015 ◽  
Vol 51 (58) ◽  
pp. 11599-11602 ◽  
Author(s):  
Kaixiang Lei ◽  
Xiaopeng Han ◽  
Yuxiang Hu ◽  
Xue Liu ◽  
Liang Cong ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Ammonium Nitrate ◽  
Oxygen Reduction ◽  
Electrocatalytic Activity ◽  
Chemical Etching ◽  
Manganese Oxides ◽  
Reduction Reaction ◽  
Ceric Ammonium Nitrate ◽  
Electrocatalytic Oxygen Reduction

Mixed-valent MnOx obtained by chemically etching MnO/Mn2O3 with ceric ammonium nitrate exhibits enhanced electrocatalytic activity toward oxygen reduction.

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