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
Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
22.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology