Adsorption of CO on Platinum Electrodes

Adsorption and oxidation of CO on platinum electrodes have been the subject of numerous investigations, due to the importance of this molecule in the electrochemical processes that occur in fuel cells. The potential at which CO is oxidized depends on the potential at which it was previously adsorbed. It depends also on the coverage of the surface and is sensitive to the structure (i.e., the process is different according to the superficial crystallographic orientation). Furthermore, various authors have suggested the possibility of CO being reduced, at least partially, in the presence of coadsorbed hydrogen. 

FIGURE 30. EMIRS spectra of CO adsorbed on Pt in 1 M HCIO4 at 25°C. Modulation at 8.5 Hz with the potential limits given in the figure. After Beden et 

Further detailed studies were made by Kunimatsu et using PM- 

FIGURE 31. Comparison of the IR absorption spectra of CO (a) from the dissociative chemisorption of 0.25 M HCOOH on Pt in 0.25 M H2SO4 (EMIRS spec-trum) and (b) at the Pt(lll)-gaseous CO interface (IRRAS spectrum).  

FIGURE 33. Plots of the integrated IR absorption intensity, the band center wavenumber, and the linewidth versus the electrode potential for CO adsorbed on a Pt electrode in 0.5 M H2SO4 (a) At 0.4 V versus SHE (b) at 0.05 V versus SHE.  

---