I like to invesitigate how metal nanoparticles can be oxidised to oxides without using high temperature (calcination, annealling process).
Google 'Ellingham diagram' for cobalt oxide. Take a look at (for example) Figure 1 (attached) from: Reduction of Cobalt Oxide (Co3O4) by Low Temperature Hydrogen Plasma December 2014 Plasma Chemistry and Plasma Processing 35(2):387-399 DOI: 10.1007/s11090-014-9602-9 Kali Charan Sabat, R. K. Paramguru, Srimay Pradhan, B. K. Mishra
You will note that the basic thermodynamics (Gibbs free energy) is not working for you at room temperature.
Dear Charles,
We recently observed that even nanoparticles of 3-7nm oxidized in ethanol. They are very reactive, you don't need to use high temperature.
It was nanoparticles of iron nitride deposited on carbon powder.
Regards,
Emile
@ Emile The surface (5 - 10 atomic layers) of any material in air will be oxidized - easy to show with ESCA/XPS or Auger. I suspect for such small particles then the oxidation will be complete. We first showed this for Ag particles in the late-1970's where Ag is only present in the +1 oxidation state on the surface. My answer was more general in terms of bulk and thermodynamics.
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