scholarly journals Towards stable and highly active IrO2 catalysts supported on doped tin oxides for the oxygen evolution reaction in acidic media

2022 ◽  
Vol 334 ◽  
pp. 03001
Author(s):  
Sofia Delgado ◽  
Paranjeet Lakhtaria ◽  
Eva Sousa ◽  
Tiago Lagarteira ◽  
K.A. Friedrich ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Large Scale ◽  
Proton Exchange Membrane ◽  
Active Surface ◽  
Proton Exchange ◽  
Polyol Synthesis ◽  
Surface Areas ◽  
Highly Active ◽  
Tin Oxides ◽  
Metal Doped

Iridium oxide is the preferred catalyst for water oxidation but it is required to maximize its utilization to deploy Proton Exchange Membrane Water Electrolyzers (PEMWEs) into the large-scale applications panorama. A promising pathway for dispersing this precious catalyst is on an electric conductive and stable support. However, there is a lack of understanding how the support-catalyst interactions affect the stability/activity of the electrocatalyst under anodic conditions. This work discloses a modified, easy-scalable, polyol synthesis protocol to produce a highly active and stable iridium-based catalyst, supported on metal-doped tin oxides. The loading of Ir was reduced 30 wt.% compared to the reference IrO2, and dispersed on Sb-SnO2 (IrOx/ATO), In-SnO2 (IrOx/ITO) and SnO2 supports. All synthesized electrocatalysts not only surpassed the OER-mass activity of a commercial catalyst (IrO2) – reference – but also reached higher electrochemical active surface areas and enhanced stability under the OER conditions. The highest performance was achieved with Ir NPs supported on ITO (176 A/gIr vs. 15.5 A/gIr for the reference catalyst @ 1.51 V vs. RHE) and both IrOx/ITO and IrOx/SnO2 catalysts demonstrated remarkable stability after cycling the electrode and performing long-term chronopotentiometry. ITO is, therefore, an auspicious support to serve Ir-based catalysts as it favors a good bargain between activity and stability, while drastically reducing the amount of noble metal.

scholarly journals Mixed Metal-Antimony Oxide Nanocomposites: Low pH Water Oxidation Electrocatalysts with Outstanding Durability at Ambient and Elevated Temperatures

2021 ◽  
Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Density Functional ◽  
Proton Exchange Membrane ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Proton Exchange ◽  
Efficient Production ◽  
Highly Active ◽  
Antimony Oxides ◽  
Electrochemical Water Splitting

Electrochemical water splitting with a proton-exchange membrane electrolyte provides many advantages for the energy-efficient production of high-purity H<sub>2</sub> in a sustainable manner, but the current technology relies on high loadings of expensive and scarce iridium at the anodes, which are also often unstable in operation. To address this, the present work scrutinises the electrocatalytic properties of a range of mixed antimony-metal (Co, Mn, Ni, Fe, Ru) oxides synthesised as thin films by a simple solution-based method for the oxygen evolution reaction in aqueous 0.5 M H<sub>2</sub>SO<sub>4</sub>. Among the noble-metal free catalysts, cobalt-antimony and manganese-antimony oxides demonstrate good stability over 24 h and reasonable activity at 24 ± 2 °C, but slowly lose their initial activity at elevated temperatures. The ruthenium-antimony system is highly active, requiring an overpotential of only 0.39 ± 0.03 and 0.34 ± 0.01 V to achieve 10 mA cm<sup>-2</sup> at 24 ± 2 and 80 °C, respectively, and most importantly, remaining remarkably stable during one-week tests at 80 °C. Detailed characterisation reveals that the enhanced stability of metal-antimony oxides water oxidation catalysts can arise from two distinct structural scenarios: either formation of a new antimonate phase, or nanoscale intermixing of metal and antimony oxide crystallites. Density functional theory analysis further indicates that the stability in operation is supported by the enhanced hybridisation of the oxygen p- and metal d-orbitals induced by the presence of Sb.

scholarly journals CFD Modelling of a Hydrogen/Air PEM Fuel Cell with a Serpentine Gas Distributor

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 564
Author(s):  
Alessandro d’Adamo ◽  
Matteo Riccardi ◽  
Massimo Borghi ◽  
Stefano Fontanesi
Keyword(s):  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Catalyst Layer ◽  
Active Surface ◽  
Reaction Rates ◽  
Transport Processes ◽  
Proton Exchange ◽  
Sustainable Mobility ◽  
Cfd Modelling ◽  
Gas Distributor

Hydrogen-fueled fuel cells are considered one of the key strategies to tackle the achievement of fully-sustainable mobility. The transportation sector is paying significant attention to the development and industrialization of proton exchange membrane fuel cells (PEMFC) to be introduced alongside batteries, reaching the goal of complete de-carbonization. In this paper a multi-phase, multi-component, and non-isothermal 3D-CFD model is presented to simulate the fluid, heat, and charge transport processes developing inside a hydrogen/air PEMFC with a serpentine-type gas distributor. Model results are compared against experimental data in terms of polarization and power density curves, including an improved formulation of exchange current density at the cathode catalyst layer, improving the simulation results’ accuracy in the activation-dominated region. Then, 3D-CFD fields of reactants’ delivery to the active electrochemical surface, reaction rates, temperature distributions, and liquid water formation are analyzed, and critical aspects of the current design are commented, i.e., the inhomogeneous use of the active surface for reactions, limiting the produced current and inducing gradients in thermal and reaction rate distribution. The study shows how a complete multi-dimensional framework for physical and chemical processes of PEMFC can be used to understand limiting processes and to guide future development.

The development of a highly durable Fe-N-C electrocatalyst with favorable CNT structures for the oxygen reduction in PEMFCs

2021 ◽  
pp. 1-7
Author(s):  
Shuiyun Shen ◽  
Ziwen Ren ◽  
Silei Xiang ◽  
Shiqu Chen ◽  
Zehao Tan ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Oxygen Reduction ◽  
Proton Exchange Membrane ◽  
Metal Organic Framework ◽  
High Energy ◽  
Proton Exchange ◽  
Rotating Disk Electrode ◽  
High Energy Density ◽  
Pt Catalyst ◽  
Highly Active

Abstract Proton exchange membrane fuel cell (PEMFC) is a crucial route for energy saving, emission reduction and the development of new energy vehicles because of its high power density, high energy density as well as the low operating temperature which corresponds to fast starting and power matching. However, the rare and expensive Pt resource greatly hinders the mass production of fuel cell, and the development of highly active and durable non-precious metal catalysts toward the oxygen reduction reaction (ORR) in the cathode is considered to be the ultimate solution. In this article, a highly active and durable Fe-N-C catalyst was facilely derived from metal organic framework materials (MOFs), and a favorable structure of carbon nanotubes (CNTs) were formed, which accounts for a desired good durability. The as-optimized catalyst has a half-wave potential of 0.84V for the ORR, which is comparable to that of commercial Pt/C. More attractively, it has good stabilities both in rotating disk electrode and single cell tests, which provides a large practical application potential in the replacement of Pt catalyst as the ORR electrocatalyst in fuel cells.

scholarly journals Mixed Metal-Antimony Oxide Nanocomposites: Low pH Water Oxidation Electrocatalysts with Outstanding Durability at Ambient and Elevated Temperatures

2021 ◽  
Author(s):  
Luke Sibimol ◽  
Manjunath Chatti ◽  
Asha Yadav ◽  
Brittany Kerr ◽  
Jiban Kangsabanik ◽  
...  
Keyword(s):  
Water Oxidation ◽  
High Performance ◽  
Density Functional ◽  
High Stability ◽  
Proton Exchange Membrane ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Proton Exchange ◽  
Efficient Production ◽  
Ambient Conditions

Proton-exchange membrane water electrolysers provide many advantages for the energy-efficient production of H<sub>2</sub>, but the current technology relies on high loadings of expensive iridium at the anodes, which are often unstable in operation. To address this, the present work scrutinises the properties of antimony-metal (Co, Mn, Ni, Fe, Ru) oxides synthesised as flat thin films by a solution-based method for the oxygen evolution reaction in 0.5 M H<sub>2</sub>SO<sub>4</sub>. Among the non-noble-metal catalysts, only cobalt-antimony and manganese-antimony oxides demonstrate high stability and reasonable activity under ambient conditions, but slowly lose activity at elevated temperatures. The ruthenium-antimony system is highly active, requiring an overpotential of 0.39 ± 0.03 and 0.34 ± 0.01 V to achieve 10 mA cm<sup>-2</sup> at 24 ± 2 and 80 °C, respectively, and remaining remarkably stable during one-week tests at 80 °C. The <i>S</i>-number for this catalyst is higher than that for the high-performance benchmark Ir-based systems. Density functional theory analysis and physical characterisation reveal that this high stability is supported by the enhanced hybridisation of the oxygen p- and metal d-orbitals induced by antimony, and can arise from two distinct structural scenarios: either formation of an antimonate phase, or nanoscale intermixing of metal and antimony oxide crystallites.

Non Precious Metal Catalysts: A Fuel Cell and ORR Study of Thermally Synthesized Nickel and Platinum Mixed Nickel Nanotubes for PEMFC

2021 ◽  
Vol 875 ◽  
pp. 193-199
Author(s):  
Ahmad Shahbaz ◽  
Ali Afaf ◽  
Nawaz Tahir ◽  
Ullah Abid ◽  
Saher Saim
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Rotating Disk ◽  
Platinum Group Metal ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Rotating Disk Electrode ◽  
Highly Active ◽  
Precious Metal Catalysts

A highly active Platinum Group Metal (PGM) and non-PGM electrocatalysts with thermally extruded nanotubes have been prepared for Proton Exchange Membrane (PEM) fuel cell by sintering Nickel zeolitic imidazole framework (Ni-ZIF). Preeminent electro-catalytic activities have been observed through single fuel cell tests and rotating disk electrode (RDE). This study involves the comparison of Oxygen Reduction Reaction (ORR) activities and fuel cell (FC) test station performance of two catalyst Nickel and Platinum mixed Nickel nanotubes (Ni NT, Ni/Pt NT) respectively. The acidic cells with corresponding Ni and Ni/Pt catalysts delivers peak power densities of 325 mWcm-2 and 455 mWcm-2 at 75 °C inside fuel cell. Our results indicate that, the synthesized Nickel nanotubes has profound effect on catalytic performance of both PGM and non-PGM electro catalysts.

Influence of Manufacturing Parameters on MEA and PEMFC Performance

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Aránzazu Barrio ◽  
Javier Parrondo ◽  
Jose Ignacio Lombraña ◽  
Maria Uresandi ◽  
Federico Mijangos
Keyword(s):  
Proton Exchange Membrane ◽  
Linear Sweep Voltammetry ◽  
Active Surface ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Point Of View ◽  
Active Surface Area ◽  
Alternative Power ◽  
Operational Range ◽  
Exchange Membrane

Proton-exchange membrane fuel cells (PEMFC) are regarded as a possible alternative power source for stationary and mobile applications. Due to the catalyst costs, many researchers have been studying the membrane and the electrode assembly (MEA) manufacturing processes that can reduce the content of Pt in the electrocatalyst layer while maintaining the performance. The MEA is the heart of the PEMFC and the catalyst plays an important role in the fuel cell operation.There are different methods to prepare MEA. In this work, the catalyst ink was straightly applied on the gas diffusion layer (GDL) by an aerograph. Then, this electrode was assembled to the membrane by hot press.From the point of view of operation, the main variables are: temperature, pressure and time of press. Operational range was established from previous experiments to find roughly the optimal conditions. Finally, these MEAs were tested in a 5 cm2 PEMFC. The operational temperature was 30°C. Due to higher temperatures it was difficult to keep the humidity of the membrane constant. The operational pressure and flow were constant throughout the experiments. Different techniques to characterize the MEAs, linear sweep voltammetry and cyclic voltammetry were applied. With these techniques the permeation of hydrogen and the electrochemically active surface area of electrode catalyst were determined.With the results obtained in the experiments, the optimal values of the fabrication parameters were established.

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