Be it a battery or a fuel cell, efficient electrodes are the be-all and end-all of every electrochemical cell. In the journal Angewandte Chemie, a team of Korean and American scientists has now introduced a novel material for electrodes based on affordable melamine foam and carbon black.
The high porosity significantly facilitates fast mass transport and a high number of catalytically active centers drastically increase the oxygen-reducing activity of cathodes for fuel cells and metal-air batteries.
The reaction that occurs at the cathodes of fuel cells and metal-air batteries is the electrochemical reduction of oxygen, namely the oxygen reduction reaction (ORR). This reaction is considerably inhibited because of its sluggish rate, and the efficiency of the cells is lower than it could be. The catalytic cathode must ensure that oxygen reacts with water, taking up electrons to form OH- ions in alkaline solution. The problem is that in a complex system involving solid, liquid, and gaseous reactants, transport processes are often too slow and inhibit the process, especially when discharging with higher current densities.
Cathodes made of a porous carbon support (carbon black) on which a catalytically active metal like platinum is finely dispersed can very effectively minimize this kinetic inhibition. However, they are expensive and not very stable, thus making them impractical for widespread application. A team led by Jaephil Cho at the Ulsan National Institute of Science and Technology (Korea) and Meilin Liu at the Georgia Institute of Technology (USA) thus aimed to develop a more economical alternative.
They were inspired by the tetrapod structure (Greek tetra: four, podes: feet) of breakwaters to synthesize a new highly efficient electrocatalyst. Tetrapods, whose four “feet” are pointed toward the corners of an imaginary tetrahedron, are constructed at the coast as well as near dams and piers to reduce the force of waves crashing against the shore. These structures also provide sanctuary for marine life forms in their many large cavities. When melamine foam is pyrolyzed and ground with a mortar and pestle, it forms microscopic fragments resembling tetrapods.
The scientists treated melamine foam with iron chloride and nitrogen-doped ketjenblack (conducting pellets of carbon black). They carbonized this product and extracted it with sulfuric acid. The resulting nanotetrapods studded with nanoparticles of carbon black have a very high specific surface area, a large number of catalytically active centers (Fe/Fe3C, and CN groups), and many pores that allow for rapid mass transport. Cathodes made of this new electrode material are highly durable and excellent performance, comparable to those of metal-based cathodes – at a much lower price. These may represent a highly promising starting point for a new generation of inexpensive and highly efficient metal-air batteries and fuel cells.
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201207193
Jaephil Cho | Angewandte Chemie
Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz
Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences