Composition-Controlled PtCo Alloy Nanocubes with Tuned Electrocatalytic Activity for Oxygen Reduction

다국어 초록 (Multilingual Abstract)

<P>Modification of the electronic structure and lattice contraction of Pt alloy nanocatalysts through control over their morphology and composition has been a crucial issue for improving their electrocatalytic oxygen reduction reaction (ORR) activity. In the present work, we synthesized PtCo alloy nanocubes with controlled compositions (Pt<SUB><I>x</I></SUB>Co NCs, <I>x</I> = 2, 3, 5, 7, and 9) by regulating the ratio of surfactants and the amount of Co precursor to elucidate the effect of the composition of nanocatalysts on their ORR activity. Pt<SUB><I>x</I></SUB>Co NCs had a Pt-skin structure after electrochemical treatment. The electrocatalysis experiments revealed a strong correlation between ORR activity and Co composition. Pt<SUB>3</SUB>Co NCs exhibited the best ORR performance among the various Pt<SUB><I>x</I></SUB>Co NCs. From density functional theory calculations, a typical volcano-type relationship was established between ORR activity and oxygen binding energy (<I>E</I><SUB>OB</SUB>) on NC surfaces, which showed that Pt<SUB>3</SUB>Co NCs had the optimal <I>E</I><SUB>OB</SUB> to achieve the maximum ORR activity. X-ray photoelectron spectroscopy and X-ray diffraction measurements demonstrated that the electronic structure and lattice contraction of the Pt<SUB><I>x</I></SUB>Co NCs could be tuned by controlling the composition of NCs, which are highly correlated with the trends of <I>E</I><SUB>OB</SUB> change.</P><P><B>Graphic Abstract</B>
<IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2012/aamick.2012.4.issue-11/am301824w/production/images/medium/am-2012-01824w_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am301824w'>ACS Electronic Supporting Info</A></P>