A blog about condensed matter and nanoscale physics. Why should high energy and astro folks have all the fun?
Monday, May 21, 2012
Catalysis seems like magic.
In our most recent paper, we found that we could dope a particularly interesting material, vanadium dioxide, with atomic hydrogen, via "catalytic spillover". By getting hydrogen in there in interstitial sites, we could dramatically alter the electrical properties of the material, allowing us to stabilize its unusual metallic state down to low temperatures. The funkiest part of this to me is the catalysis part. The metal electrodes that we use for electronic measurements have enough catalytic activity that they can split hydrogen molecules into atomic hydrogen at an appreciable rate even under very modest conditions (e.g., not much warmer than the boiling point of water). This paper (sorry it is subscription only) shows an elegant experimental demonstration of this, where gold is exposed to H2 and D2 gas and HD molecules are then detected. I would love to understand the physics at work here better. Any recommendations for a physics-based discussion would be appreciated - I know there is enormous empirical and phenomenological knowledge about this stuff, but something closer to an underlying physics description would be excellent.
Disclaimer - I don't work in this area (although I am fairly interested in it), so hopefully someone else will chime in on this topic. I'm not quite sure where the line lies between "underlying physics" and "phenomenology," so I apologize in advance should anything mentioned not be quite what you're looking for on this topic. Most of the recommendations tend to be strong on the electronic structure theory/quantum chemistry front, for what it's worth.
ReplyDeleteI'm going to presume here that you are referring to heterogeneous catalysis in general (and not just gold nanoparticles in particular). One suggestion is to check out the work of Jens Norskov (presently at Stanford, previously at TU-Denmark). He co-authored a review for J. Chem. Phys. a few years ago on this topic (http://dx.doi.org/10.1063/1.2839299), as well as another on the role of the active site in catalysis (http://dx.doi.org/10.1039/b800260f). In my notes, I have a recommendation to investigate a text - Molecular Heterogenous Catalysis: A Conceptual and Computational Approach by Neurock & van Santen.
Insofar as gold in particular, there's a lot. I won't even pretend to have a handle on it outside of recreational reading. Having said that, there's a review on gold catalysis (focusing on CO oxidation) from the Willock group at Cardiff here - http://dx.doi.org/10.1039/b707385m. Most of what I seem to stumble across tends to be CO oxidation chemistry, although I do recall the Armentrout group (Utah) was interested in hydrogen & deuterium reactions with gold clusters.
I hope that some of this turns out to be helpful...
MJ, thanks very much for the suggestions. I'll definitely check them out!
ReplyDeleteYes. Norskov approaches catalysis from a perspective of a condensed matter physicist. I like his d-band theory as laid out in Hammer and Norskov "Why gold is the noblest of all the metals", Nature 376, 238 (1995).
ReplyDeleteDeals with H on Ni, Cu, Pt, Au.