[Alexey]

This topic will be splitted to corresponding areas of chemistry when starts growing.

[Guest]

hi,

maybe this topic ist too general but interesting in any case:

biokinetic transport through (biological) membranes;

this topic corresponds with some parts of organic and biochemistry, physical chemistry and medicine;

aspetially small mediatormolecules are pretty unknown and very important facing deceases like cancer, aids, ... .

[Guest]

Ad physical chemistry:

Another important point in electrochemistry may be the easy and fast determination of the exact amount (ratio) of "normal" (organic) reaction : electrochemically induced one;

If one choose a very slow sweep rate (means the rate of increasing the voltage in cyclic voltammetry) the reaction that takes place will be influenced (caused) mostly due to "normal" (organic) chemistry; in comparison to that: If one choose a very fast sweep rate there is not that much time for that and the reaction that takes place will be caused due to the application of this voltage;

Normally one can choose these sweeprate more or less free

Sometimes it is very hard to separate those two parts and identify (and/or avoid) products

[Guest]

[Guest]

What about "the fuel cell"?

Storage, detection, safety and simple usage, decreasing of costs, cost-performance ratio, capacity of hydrogen-systems, possible use in automobile industry

... as already used in space vehicles ...


interrested? have a look at:
R. C. Bowman Jr., 2. Int. Symposium on Hydrogen in Matter (IOHIM) 2006
http://www.nasa.gov/missions/highlights/schedule.html
http://spaceflight.nasa.gov/gallery/video/shuttle/sts-116/html/fd1.html

[Guest]

[Maria]

[Piero]

As I understand, the Project "Breakthrough Problems in Chemistry" is not about just interesting challenges, but about challenges, solution of which will cause breakthroughs. I think the Guest is right, and the generally formulated challenge "fuel cell" is not a challenge anymore, since it's widely used. Maria, please, specify your challenge: what is missing and what is the exact challenge in fuel cells at the present time? and why the solution will be a breakthrough?

[Maria]

Hi Piero,

it's still a contemporary issue.
But I do agree one needs to specify:

Let’s focus on:
1) Direct-Methanol Fuel Cell (DMFC)
2) Polymer Electrolyte Fuel Cell (PEMFC)

In both cases work centres on the optimization of cell components.

Ad 1:
efficient reduction of O2 at the cathode (which is still very slow (kinetic) - even if Pt/C is used)
- an extremely high excess voltage occurs

oxidation of methanol (ethanol, …)
(which is still very slow (kinetic) – on standard catalysts as PtRu/C for instance)

polymer electrolyte membranes (perfluorosulfonic acid based membranes, ...)

Ad 2:
are low-temperature fuel cells (gen. 85±105 °C) which use a proton exchange membrane as an electrolyte; (first to be used in Space (Gemini: 1kW fuel cell stack as an auxiliary power source, etc.)) A major breakthrough in the field of PEM fuel cells came with the use of Nafion® membranes by DuPont. BUT: Some other (PTFE based) polymers are still under scrutinous investigation by several research groups.
(like for instance:
molecular architecture in which water-soluble dendrimers are grafted onto a linear polymer
or
membrane preparation with grafting (lower oxygen solubility but higher diffusion than through Nafion®) or plasma polymerisation (highly cross-linked, uniform and stable thin films)

they prove to be mechanically and electrochemically stable

best regards
Maria

[Piero]

Maria, I don't have any doubts that there are a lot of things to optimize. We are not talking about small optimizations.
The question is: why this optimization will be a breakthrough? What will be REALLY different from what is possible now? Why is this DIFFERENCE is soooo important?

[Maria]

Well. Don't you think that it would be a big improvement if one is able to speed up the mentioned reactions and/or develop new membranes and/or catalysts to increase efficiency significantly? It’s also a commercial advantage if those cells are smaller (less number of stacks), cheaper and more efficient. It would be a breakthrough if these systems were able to replace conventional energy resources.Many of these investigations are still promising to lead to patents and publications.

[Piero]

[lchadwick]

What if there were one single box capable of purifying anything from metals to natural products to proteins, all with guaranteed 100% sample recovery? The question is: would "easy" access to purified chemicals (including highly labile to poorly soluble ones) lead to any radical change in the pace of biological/biochemical discovery? Has anyone here (n)ever been confounded by the "bottleneck" of purification?