title: Five-fold twinned Pd2NiAg nanocrystals with increased surface Ni site availability to improve oxygen reduction activity.
abstract: The synthesis of highly active oxygen reduction reaction (ORR) catalysts with good durability and low cost is highly desirable but still remains a significant challenge. In this work, we present the synthesis of five-fold twinned Pd2NiAg nanocrystals (NCs) with a Ni-terminal surface which exhibit excellent electrocatalytic performance for ORR in alkaline media, even better than the performance of the commercial Pt/C catalyst. Using high-angle annular-dark-field imaging together with density functional theory calculations, it is found that the surfaces of the five-fold twinned Pd2NiAg NCs exhibit an unusual valence electron density. The maximum catalytic activity originates from the increased availability of surface Ni sites in five-fold twinned Pd2NiAg NCs and the features of twinned structural defects. This study provides an explanation of the enhanced ORR from the special structure of this novel material, which opens up new avenues for the design of novel classes of electrocatalysts for fuel cells and metal-air batteries.
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials and Jiangsu Key Laboratory of Biofunctional Materials, School of Chemistry and Materials Science, Nanjing Normal University , Nanjing 210023, P. R. China.
authors.forename: Suli
authors.initials: S
authors.lastname: Liu
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yafei
authors.initials: Y
authors.lastname: Li
authors.forename: Min
authors.initials: M
authors.lastname: Han
authors.forename: Lin
authors.initials: L
authors.lastname: Gu
authors.forename: Cewen
authors.initials: C
authors.lastname: Nan
authors.forename: Jianchun
authors.initials: J
authors.lastname: Bao
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Dai
mesh_terms: D002384:Catalysis; D004563:Electrochemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009532:Nickel / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D012834:Silver; D010165:Palladium; D009532:Nickel; D010100:Oxygen