title: Composition-controlled PtCo alloy nanocubes with tuned electrocatalytic activity for oxygen reduction.
abstract: 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(x)Co NCs, x = 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(x)Co NCs had a Pt-skin structure after electrochemical treatment. The electrocatalysis experiments revealed a strong correlation between ORR activity and Co composition. Pt₃Co NCs exhibited the best ORR performance among the various Pt(x)Co NCs. From density functional theory calculations, a typical volcano-type relationship was established between ORR activity and oxygen binding energy (E(OB)) on NC surfaces, which showed that Pt₃Co NCs had the optimal E(OB) 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(x)Co NCs could be tuned by controlling the composition of NCs, which are highly correlated with the trends of E(OB) change.
authors.affiliation: Department of Chemistry, KAIST, Daejeon 305-701, Korea.
authors.forename: Sang-Il
authors.initials: SI
authors.lastname: Choi
authors.forename: Su-Un
authors.initials: SU
authors.lastname: Lee
authors.forename: Woo Youn
authors.initials: WY
authors.lastname: Kim
authors.forename: Ran
authors.initials: R
authors.lastname: Choi
authors.forename: Kwangwoo
authors.initials: K
authors.lastname: Hong
authors.forename: Ki Min
authors.initials: KM
authors.lastname: Nam
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Han
authors.forename: Joon T
authors.initials: JT
authors.lastname: Park
mesh_terms: D000497:Alloys / Q000737:chemistry; D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D003460:Crystallization / Q000379:methods; D004563:Electrochemistry / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010316:Particle Size; D010984:Platinum / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D000497:Alloys; D046911:Macromolecular Substances; D003035:Cobalt; D010984:Platinum; D010100:Oxygen