scholarly journals Sputtered Platinum Thin-films for Oxygen Reduction in Gas Diffusion Electrodes: A Model System for Studies under Realistic Reaction Conditions

Surfaces ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 336-348 ◽  
Author(s):  
Gustav W. Sievers ◽  
Anders W. Jensen ◽  
Volker Brüser ◽  
Matthias Arenz ◽  
María Escudero-Escribano
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction ◽  
Specific Activity ◽  
Early Stage ◽  
Gas Diffusion ◽  
Rotating Disk Electrode ◽  
Membrane Electrode ◽  
Catalyst Characterization ◽  
Reaction Conditions ◽  
Electrode Potentials

The development of catalysts for the oxygen reduction reaction in low-temperature fuel cells depends on efficient and accurate electrochemical characterization methods. Currently, two primary techniques exist: rotating disk electrode (RDE) measurements in half-cells with liquid electrolyte and single cell tests with membrane electrode assemblies (MEAs). While the RDE technique allows for rapid catalyst benchmarking, it is limited to electrode potentials far from operating fuel cells. On the other hand, MEAs can provide direct performance data at realistic conditions but require specialized equipment and large quantities of catalyst, making them less ideal for early-stage development. Using sputtered platinum thin-film electrodes, we show that gas diffusion electrode (GDE) half-cells can be used as an intermediate platform for rapid benchmarking at fuel-cell relevant current densities (~1 A cm−2). Furthermore, we demonstrate how different parameters (loading, electrolyte concentration, humidification, and Nafion membrane) influence the performance of unsupported platinum catalysts. The specific activity could be measured independent of the applied loading at potentials down to 0.80 VRHE reaching a value of 0.72 mA cm−2 at 0.9 VRHE in the GDE. By comparison with RDE measurements and Pt/C measurements, we establish the importance of catalyst characterization under realistic reaction conditions.

scholarly journals Pt nanoparticles supported on nitrogen-doped porous carbon as efficient oxygen reduction catalysts synthesized via a simple alcohol reduction method

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Naoki Tachibana ◽  
Yasuyuki Yukawa ◽  
Kazuo Morikawa ◽  
Masahiro Kawaguchi ◽  
Kengo Shimanoe
Keyword(s):  
Oxygen Reduction ◽  
Porous Carbon ◽  
Reduction Method ◽  
Specific Activity ◽  
Pt Nanoparticles ◽  
Gas Diffusion ◽  
Rotating Disk Electrode ◽  
High Catalytic Activity ◽  
Nitrogen Doped ◽  
Alcohol Reduction

Abstract Pt nanoparticles supported on nitrogen-doped porous carbon (NPC) were investigated as both a highly active catalyst for the oxygen reduction reaction (ORR) and a suitable porous support structure. Pt/NPC catalysts with loadings of 8.8–35.4 wt.% were prepared via a simple alcohol reduction method and exhibited homogeneously dispersed Pt nanoparticles with a small mean size ranging from 1.90 to 2.99 nm. X-ray photoelectron spectroscopy measurement suggested the presence of strong interactions between the Pt nanoparticles and NPC support. 27.4% Pt/NPC demonstrated high catalytic activity for the ORR in a rotating disk electrode system and was also effectively applied to a gas diffusion electrode (GDE). A GDE fabricated using the Pt/NPC with a fine pore network exhibited excellent performance, especially at high current densities. Specific activity of Pt/NPC and Pt/carbon black catalysts for the ORR correlated with the peak potential of adsorbed OH reduction on Pt, which was dependent on the particle size and support. Graphic abstract

scholarly journals Methanol-Tolerant M–N–C Catalysts for Oxygen Reduction Reactions in Acidic Media and Their Application in Direct Methanol Fuel Cells

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 650 ◽  
Author(s):  
Carmelo Lo Vecchio ◽  
David Sebastián ◽  
María Lázaro ◽  
Antonino Aricò ◽  
Vincenzo Baglio
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction ◽  
Large Scale ◽  
High Efficiency ◽  
Direct Methanol Fuel Cells ◽  
Cell System ◽  
Rotating Disk Electrode ◽  
Capital Costs ◽  
Direct Methanol ◽  
Methanol Fuel Cells

Direct methanol fuel cells (DMFCs) are emerging technologies for the electrochemical conversion of the chemical energy of a fuel (methanol) directly into electrical energy, with a low environmental impact and high efficiency. Yet, before this technology can reach a large-scale diffusion, specific issues must be solved, in particular, the high cost of the cell components. In a direct methanol fuel cell system, high capital costs are mainly derived from the use of noble metal catalysts; therefore, the development of low-cost electro-catalysts, satisfying the target requirements of high performance and durability, represents an important challenge. The research is currently addressed to the development of metal–nitrogen–carbon (M–N–C) materials as cheap and sustainable catalysts for the oxygen reduction reaction (ORR) in an acid environment, for application in polymer electrolyte fuel cells fueled by hydrogen or alcohol. In particular, this mini-review summarizes the recent advancements achieved in DMFCs using M–N–C catalysts. The presented analysis is restricted to M–N–C catalysts mounted at the cathode of a DMFC or investigated in rotating disk electrode (RDE) configuration for the ORR in the presence of methanol in order to study alcohol tolerance. The main synthetic routes and characteristics of the catalysts are also presented.

scholarly journals Oxygen Reduction Reaction on Polycrystalline Platinum: On the Activity Enhancing Effect of Polyvinylidene Difluoride

Surfaces ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 69-77
Author(s):  
Alessandro Zana ◽  
Gustav Wiberg ◽  
Matthias Arenz
Keyword(s):  
Mass Transport ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Surface Area ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Rotating Disk Electrode ◽  
Membrane Electrode ◽  
Active Surface Area ◽  
Polyvinylidene Difluoride

There have been several reports concerning the performance improving properties of additives, such as polyvinylidene difluoride (PVDF), to the membrane or electrocatalyst layer of proton exchange membrane fuel cells (PEMFC). However, it is not clear if the observed performance enhancement is due to kinetic, mass transport, or anion blocking effects of the PVDF. In a previous investigation using a thin-film rotating disk electrode (RDE) approach (of decreased complexity as compared to membrane electrode assembly (MEA) tests), a performance increase for the oxygen reduction reaction (ORR) could be confirmed. However, even in RDE measurements, reactant mass transport in the catalyst layer cannot be neglected. Therefore, in the present study, the influence of PVDF is re-examined by coating polycrystalline bulk Pt electrodes by PVDF and measuring ORR activity. The results on polycrystalline bulk Pt indicate that the effects of PVDF on the reaction kinetics and anion adsorption are limited, and that the observed performance increase on high surface area Pt/C most likely is due to an erroneous estimation of the electrochemical active surface area (ECSA) from CO stripping and Hupd.

A Feasibility Study of Ribbon Architecture for PEM Fuel Cells

2010 ◽  
Vol 7 (5) ◽  
Author(s):  
Daniel F. Walczyk ◽  
Jaskaran S. Sangra
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
High Volume ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Open Circuit ◽  
Membrane Electrode ◽  
Fixture Design ◽  
Design Development ◽  
Test Fixture

The feasibility of an alternative fuel cell architecture, called a ribbon membrane electrode assembly (MEA), is demonstrated for low-temperature polymer electrolyte membrane (PEM) fuel cells used in portable power applications by comparing it to a traditional bipolar “stack” architecture. A ribbon MEA consists of adjacent PEM cells sharing a common gas diffusion layer to allow for lateral electrical current flow and an integral gas-tight, conductive interconnect/seal, where adjacent cells meet to prevent reactant gas leakage. The resulting lateral arrangement of MEAs can be used to supply all MEAs simultaneously instead of individual bipolar plates with flow fields for a stack. A pair of two-cell ribbon MEAs, with and without an interconnect/seal, were designed, prototyped, and sealed by thermal pressing. The MEAs were clamped in a two-piece box fixture to provide reactant gases on the anode and cathode sides, hooked to a fuel cell (FC) test stand and yielded an open circuit voltage (OCV) of 1.43 V with an interconnect/seal and 0.6 V without. A two-cell bipolar stack PEMFC with identical MEA specifications had an OCV of 1.86 V. Polarization curves for the ribbon MEA with interconnect/seal showed the sensitivity of performance to clamping pressure and positioning of the copper current collectors. The ribbon MEA polarization curve was also shifted downward by 0.42 V as compared with that of the traditional stack, and suspected causes (e.g., gas leaking) are attributable to the nonoptimal test fixture design. Hence, the ribbon MEA architecture is shown to be feasible. Future work suggested includes improvements to the test fixture design, development of automated manufacturing capabilities for high volume production, and demonstration of a multicell (>2) ribbon MEA PEMFC design.

scholarly journals The Gas diffusion electrode setup as a testing platform for evaluating fuel cell catalysts: a comparative RDE-GDE study

2021 ◽  
Author(s):  
Sven Nösberger ◽  
Jia Du ◽  
Jonathan Quinson ◽  
Etienne Berner ◽  
Alessandro Zana ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Elevated Temperatures ◽  
Gas Diffusion ◽  
Liquid Electrolyte ◽  
Gas Diffusion Electrode ◽  
Rotating Disk Electrode ◽  
Intrinsic Activity ◽  
Membrane Electrode ◽  
Potential Range ◽  
Fuel Cell Catalysts

Gas diffusion electrode (GDE) setups have been recently introduced as a new experimental approach to test the performance of fuel cell catalysts. As compared to the state-of-the-art in fundamental research, i.e., rotating disk electrode (RDE) measurements, GDE measurements offer several advantages. Most importantly mass transport limitations, inherent to RDE measurements are avoided. In a GDE setup the reactant, e.g., oxygen gas, is not dissolved into a liquid electrolyte but distributed through a gas diffusion layer (GDL), as it is actually the case in fuel cells. Consequently, much higher current densities can be achieved, and the catalysts can be studied in a wider and more relevant potential range. Furthermore, direct contact to a liquid electrolyte can be avoided and elevated temperatures can be employed in a straight-forward manner. However, the use of GDE setups also comes with some challenges. The determined performance is not strictly related to the catalyst itself (intrinsic activity), but also to the quality of the catalyst film preparation. Therefore, it might be even more important than in RDE testing to develop standardized procedures to prepare catalysts inks and films that can be reproduced effortlessly in research laboratories for fundamental and applied experimentation. To develop such standardized testing protocols, we present a comparative RDE – GDE study, where we investigate several commercial standard Pt/C fuel cell catalysts with respect to the oxygen reduction reaction (ORR). The study highlights the strengths of the GDE approach as an intermediate “testing step” between RDE and membrane electrode assembly (MEA) tests when developing new fuel catalysts.

scholarly journals Nanostructured gas diffusion layer to improve direct oxygen reduction reaction in Air-Cathode Single-Chamber Microbial Fuel Cells

2022 ◽  
Vol 334 ◽  
pp. 04012
Author(s):  
Giulia Massaglia ◽  
Eve Verpoorten ◽  
Candido F. Pirri ◽  
Marzia Quaglio
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Microbial Fuel Cells ◽  
Oxygen Diffusion ◽  
Energy Recovery ◽  
Gas Diffusion ◽  
Reduction Reaction ◽  
Air Cathode ◽  
The One

The aim of this work is the development of new nanostructured-gas-diffusion-layer (GDL) to improve the overall behaviour of Air-Cathode Single-Chamber-Microbial-Fuel-Cells (SCMFCs). The design of new nanostructured-GDL allowed exploiting all nanofibers ’intrinsic properties, such as high surface ratio to volume, high porosity, achieving thus a good oxygen diffusion into the proximity of catalyst layer, favouring thus the direct oxygen-reduction-reaction (ORR). Nanostructured-GDLs were prepared by electrospinning process, using a layer-by-layer deposition to collect 2 nanofibers’ mats. The first layer was made of cellulose nanofibers able to promote oxygen diffusion into SCMFC. The second layer, placed outwards, was based on polyvinyl-fluoride (PVDF) nanofibers to prevent the electrolyte leakage. This nanostructured-GDL plays a pivotal role to improve the overall performance of Air-Cathode-SCMFCs. A maximum current density of 20 mA m-2 was obtained, which is higher than the one reached with commercial-GDL, used as reference material. All results were analysed in terms of energy recovery parameter, defined as ratio of generated power integral and the internal volume of devices, evaluating the overall SCMFC performance. SCMFCs with a nanostructured-GDL showed an energy recovery equal to 60.83 mJ m-3, which was one order of magnitude higher than the one obtained with commercial-GDL, close to 3.92 mJ m-3.

scholarly journals Improving Catalytic Activity in the Electrochemical Separation of CO2 Using Membrane Electrode Assemblies

2022 ◽  
Author(s):  
Nicholas Schwartz ◽  
Jason Harrington ◽  
Kirk J Ziegler ◽  
Philip Cox
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Catalytic Activity ◽  
Electrochemical Impedance ◽  
Gas Diffusion ◽  
Rotating Disk Electrode ◽  
Constant Current ◽  
Membrane Electrode ◽  
Active Surface Area ◽  
Separation Of Co2

Abstract The direct electrochemically driven separation of CO2 from a humidified N2, O2, and CO2 gas mixture was conducted using an asymmetric membrane electrode assembly (MEA). The MEA was fabricated using a screen-printed ionomer bound Pt cathode, an anion exchange membrane (AEM), and ionomer bound IrO2 anode. Electrocatalyst materials were physically and chemically characterized prior to inclusion within the electrode. Electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) measurements using a rotating disk electrode (RDE) were used to quantify the catalytic activity and determine the effects of the catalyst-to-ionomer ratio. Catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface analysis, and (dynamic light scattering) DLS to evaluate catalyst structure, active surface area, and determine the particle size and bulk particle size distribution (PSD). The electrocatalyst layer of the electrodes were fabricated by screen printing a uniformly dispersed mixture of catalyst, dissolved anionic ionomer, and a solvent system onto an electrode supporting gas diffusion layer (GDL). Pt IrO2 MEAs were fabricated and current-voltage relationships were determined using constant-current measurements over a range of applied current densities and flow rates. Baseline reaction kinetics for CO2 separation were established with a standard set of Pt-IrO2 MEAs.

An ultra-thin, flexible, low-cost and scalable gas diffusion layer composed of carbon nanotubes for high-performance fuel cells

2020 ◽  
Vol 8 (12) ◽  
pp. 5986-5994 ◽  
Author(s):  
Jun Wei ◽  
Fandi Ning ◽  
Chuang Bai ◽  
Ting Zhang ◽  
Guanbin Lu ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Diffusion Layer ◽  
High Performance ◽  
Proton Exchange Membrane ◽  
Low Cost ◽  
Gas Diffusion Layer ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Essential Components

A gas diffusion layer (GDL) is one of the essential components of a membrane electrode assembly (MEA), which is the core of proton exchange membrane fuel cells (PEMFCs).

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