scholarly journals Pt-free silver nanoalloy electrocatalysts for oxygen reduction reaction in alkaline media

2016 ◽  
Vol 6 (10) ◽  
pp. 3317-3340 ◽  
Author(s):  
Adnan Qaseem ◽  
Fuyi Chen ◽  
Xiaoqiang Wu ◽  
Roy L. Johnston
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Comparable Activity

Silver nanoalloy electrocatalysts with comparable activity and better stability than commercial Pt/C for oxygen reduction reaction (ORR) in advanced metal–air batteries and fuel cells.

scholarly journals Metallic Organic Framework-Derived Fe, N, S co-doped Carbon as a Robust Catalyst for the Oxygen Reduction Reaction in Microbial Fuel Cells

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3846 ◽  
Author(s):  
Xiao Luo ◽  
Wuli Han ◽  
Han Ren ◽  
Qingzuo Zhuang
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Microbial Fuel Cells ◽  
Active Sites ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
X Ray ◽  
Co Doped ◽  
Organic Framework

Oxygen reduction reaction (ORR) provides a vital role for microbial fuel cells (MFCs) due to its slow reaction kinetics compared with the anodic oxidation reaction. How to develop new materials with low cost, high efficacy, and eco-friendliness which could replace platinum-based electrocatalysis is a challenge that we have to resolve. In this work, we accomplished this successfully by means of a facile strategy to synthesize a metallic organic framework-derived Fe, N, S co-doped carbon with FeS as the main phase. The Fe/S@N/C-0.5 catalyst demonstrated outstandingly enhanced ORR activity in neutral PBS and alkaline media, compared to that of commercial 20% Pt-C catalyst. Here, we started-up and operated two parallel single-chamber microbial fuel cells of an air cathode, and those cathode catalysts were Fe/S@N/C-0.5 and commercial Pt-C (20% Pt), respectively. Scanning electron microscopy (SEM) elaborated that the Fe/S@N/C-0.5 composite did not change the polyhedron morphology of ZIF-8. According to X-ray diffractometry(XRD) curves, the main crystal phase of the resulted Fe/S@N/C-0.5 was FeS. The chemical environment of N, S, and Fe which are anticipated to be the high-efficiency active sites of ORR for MFCs were investigated by X-ray photoelectron spectroscopic(XPS). Nitrogen adsorption/desorption techniques were used to calculate the pore diameter distribution. In brief, the obtained Fe/S@N/C-0.5 material exhibited a pronounced reduction potential at 0.861 V (versus Reversible Hydrogen Electrode(RHE)) in 0.1M KOH solution and –0.03 V (vs. SCE) in the PBS solution, which both outperform the benchmark platinum-based catalysts. Fe/S@N/C-0.5-MFC had a higher Open Circuit Voltage(OCV) (0.71 V), stronger maximum power density (1196 mW/m2), and larger output voltage (0.47 V) than the Pt/C-MFC under the same conditions.

scholarly journals Degradation studies of Me-N-C catalysts for the oxygen reduction reaction in fuel cells

2018 ◽  
Author(s):  
Ιωάννα Μαρτιναίου
Keyword(s):  
Raman Spectroscopy ◽  
Fuel Cells ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Precious Metal ◽  
Load Cycle ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Precious Metal Catalysts ◽  
The Stability

The increasing demand forrenewable energy along with the requirement of decreasing CO2 emissions is a major challenge for the scientific community. Fuel cells are among the most promising electrochemical devices because of their low operating temperature and high power density. The main advantage of a fuel cell is that electrical power can be produced continuously as long as the fuel supply is provided. Another important advantage is high efficiency. The efficiency of fuel cells is superior to that of combustion engines, particularly at low loads, which makes low-temperature fuel cells (0―100 °C) attractive for automotive propulsion. State of the art catalyst for the anode as well as the cathode is typically based on platinum-supported on carbon. However, the platinum catalyst alone would account for 38-56% of the stack cost [1]. Thus the higher efficiency, in comparison to combustion engines, comes with a higher price that makes the commercialization not competitive now. As a large quantity of the precious metal is required to catalyse the oxygen reduction reaction (ORR), current research is focused on this reaction and especially on the development of alternative non-precious metal catalysts (NPMC). In order for these catalysts to be a commercially viable solution for replacing platinum-based catalysts, they should meet two criteria, improving both activity and stability of these catalysts. Despite, several milestones that have been achieved regarding the activity of these catalysts [2– 5], stability is still relatively poor in comparison to platinum-based systems. This dissertation focuses on the investigation of the stability of non-precious metal catalysts for oxygen reduction reaction mainly in acidic media for application in Proton Exchange Membrane Fuel Cells (PEMFCs) and Direct Methanol Fuel Cells (DMFCs). Α part of this study also deals with performance determination of NPMC in alkaline media, regarding their application in Alkaline Fuel Cells (AFCs). The electrochemical tests were performed with a Rotating Disk Electrode technique. Stability refers to the ability of a system to maintain performance at constant current (or voltage) conditions, while durability refers to the ability to maintain performance following a voltage cycling. First, a systematic study on the impact of the metal centre on durability was conducted. Thirteen MeN-C catalysts were examined with a Start/ Stop (SSC) durability protocol in the potential range of 1.0 V – 1.5 V. Raman spectroscopy was performed before and after the durability tests and a correlation between electrochemical evaluation and Raman spectroscopy in this potential region was found. The carbon oxidation is related to the disintegration of active MeN4 sites that might be initiated by both: the oxidation of the surrounding graphene sheets and by a displacement of the metal out of the N4 plane and this was evidenced by a decrease in the D3 band. Furthermore, a novel synthesis protocol was developed in our group and a Fe-N-C catalyst was optimized with the addition of sulfur(S) in the precursor. With respect to activity the best-off S-added catalyst and the S-free one were then examined for durability under a Load Cycle (LC) protocol (0.6– 1.0 V) in alkaline media. A modification of both catalysts with ionic liquid (IL) was introduced by the group of Professor B. J.M. Etzold within a cooperation framework. The durability of the modified S-free catalyst was found superior to the durability of the non-modified catalyst. In the case of the Sadded catalyst, the IL modification did not further improve its durability. Finally, a third synthesis approach was developed, leading to an active Fe-N-C catalyst also with sulfur in the precursor. The stability of this catalyst was investigated in a DMFC within a research stay abroad project in collaboration with Professor S. Specchia from Politecnico di Torino and subsequently examined by post mortem Mössbauer spectroscopy. This catalyst was further evaluated with a Load Cycle durability protocol and post mortem Raman spectroscopy in our laboratories.

Assessing the Oxygen Reduction Reaction by a 2-electron Mechanism on Ceria Surfaces

2021 ◽  
Author(s):  
Mauro C dos Santos ◽  
Lanna Lucchetti ◽  
James Almeida ◽  
Pedro Alves da Silva Autreto
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduction Reaction

The 2-electron pathway of the oxygen reduction reaction is an unwanted process in the development of fuel cells. In contrast, it has gained the scientific community’s attention due to its...

scholarly journals Design of ternary Pt-CoZn alloy catalysts coated with N-doped carbon towards acidic oxygen reduction

2021 ◽  
Author(s):  
Xieweiyi Ye ◽  
Yakun Xue ◽  
Kaijia Li ◽  
Wen Tang ◽  
Xiao Han ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Proton Exchange Membrane ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Commercial Applications ◽  
Exchange Membrane ◽  
Alloy Catalysts

Improving the activity and durability of Pt-based electrocatalysts used in the acidic oxygen reduction reaction (ORR) is a great task for the commercial applications of proton-exchange membrane fuel cells. Alloying...

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