Electroreduction of O2 on uniform arrays of Pt and PtCo nanoparticles

The fabrication of uniform arrays of Pt and PtCo nanoparticles with controlled size and interparticle distance is reported. These particle arrays are ideal model catalysts for exploring particle size and other structural effects on reactivity without the complications from particle aggregation and particle surface protecting molecular layer. Electroreduction of O2 on these particle arrays was used to elucidate their applications as electrocatalysts. The cyclic voltammetric results on Pt particles show that with increasing interparticle spacing, the O2 reduction peak shifts to negative potentials and the current density increases significantly. Meanwhile, the voltammogram transforms from a peak to a mixed peak-sigmoidal shape. These voltammetric changes is attributed to the O2 mass transport pattern change. No apparent advantage of using PtCo was observed as the cyclic voltammogram of O2 reduction on PtCo is very similar to that obtained on Pt.