persistent controversy in catalysts for fuel cells has just been solved by a team of researchers from the Faculty of Pure and Applied Sciences at the University of Tsukuba.
The oxygen reduction reaction is a key step in the operation of fuel cells, but depends on expensive precious metal-based catalysts. Carbon-based catalysts with added nitrogen are among the most promising alternatives to precious metals, and could allow more widespread use of fuel cell technology. However, until now, the arrangement of nitrogen and carbon that gave the catalytic effect remained a mystery, stalling efforts to develop more effective materials.
In an article published this week in Science, a team of researchers from the University of Tsukuba identified the catalytic structure and proposed a mechanism by which the reaction works. "We knew that nitrogen-doped carbon was a good oxygen reduction catalyst, but no one was sure whether the nitrogen was pyridinic or graphitic," said corresponding author Prof. Junji Nakamura.
To solve the mystery, the team fabricated four model catalyst substrates, which simulated competing potential structures and analyzed their reaction performance. Pyridinic nitrogen, or nitrogen atoms bonded to two carbon atoms, occur mainly at the edges of the material. By patterning the substrates to change the number of edges, the team could control the presence of pyridinic nitrogen and measure how it affected the catalytic performance. These results showed that the active catalytic sites were associated with pyridinic nitrogen.
Taking the research a step further, the investigators then proposed the various stages of the reaction mechanism after finding that it was actually the carbon atom next to the nitrogen that was the active site rather than the nitrogen atom itself. As the corresponding author Prof. Nakamura noted: "Clarifying the active site and mechanism is a great step forward and will allow optimization studies to focus on driving up catalyst performance."
Masataka Watanabe | EurekAlert!
Spider silk key to new bone-fixing composite
20.04.2018 | University of Connecticut
Diamond-like carbon is formed differently to what was believed -- machine learning enables development of new model
19.04.2018 | Aalto University
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy