T. Inasaki, S. Kobayashi / Electrochimica Acta 54 (2009) 4893–4897
4897
4. Conclusions
The particle size effects of gold catalysts on the oxygen reduc-
tion in acidic medium have been investigated. For this purpose,
we chemically prepared gold nanoparticles with narrow and con-
trolled size distributions and deposited onto a carbon support.
The gold particles with the mean diameter 1.7 0.5, 4.8 2 and
13.2 2 nm were synthesized. In the case of bulk gold, the value of
n is nearly constant at potential above −0.2 V. On the other hand, the
increase of n was observed for Au particles less than 10–15 nm as
the potential shifted to more negative value, indicating that activity
of the 2-step 4-electron reduction was high or the direct 4-electron
reduction of O2 to H2O occurred. The maximum increase of n was
observed when the particle size of Au was less than 3 nm.
Appendix A. Supplementary data
Fig. 8. Potential dependence of n for the Au/C-modified GC electrodes and bulk Au
electrode in 0.5 M H2SO4.
Supplementary data associated with this article can be found, in
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