Organic-inorganic hybrid PtCo nanoparticle with high electrocatalytic activity and durability for oxygen reduction

Abstract

In Pt-transition metal (TM) alloy catalysts, the electron transfer from the TM to Pt is retarded owing to the inevitable oxidation of the TM surface by oxygen. In addition, acidic electrolytes such as those employed in fuel cells accelerate the dissolution of the surface TM oxide, which leads to catalyst degradation. Herein, we propose a novel synthesis strategy that selectively modifies the electronic structure of surface Co atoms with N-containing polymers, resulting in highly active and durable PtCo nanoparticle catalysts useful for the oxygen reduction reaction (ORR). The polymer, which is functionalized on carbon black, selectively interacts with the Co precursor, resulting in Co-N bond formation on the PtCo nanoparticle surface. Electron transfer from Co to Pt in the PtCo nanoparticles modified by the polymer is enhanced by the increase in the difference in electronegativity between Pt and Co compared with that in bare PtCo nanoparticles with the TM surface oxides. In addition, the dissolution of Co and Pt is prevented by the selective passivation of surface Co atoms and the decrease in the O-binding energy of surface Pt atoms. As a result, the catalytic activity and durability of PtCo nanoparticles for the ORR are significantly improved by the electronic ensemble effects. The proposed organic/inorganic hybrid concept will provide new insights into the tuning of nanomaterials consisting of heterogeneous metallic elements for various electrochemical and chemical applications.

Bimetallic AuRh nanodendrites consisting of Au icosahedron cores and atomically ultrathin Rh nanoplate shells: synthesis and light-enhanced catalytic activity

“…[1][2][3][4][5][6] The physical and chemical properties of bimetallic noble metal nanostructures not only depend on their chemical compositions but also are related to their morphologies. [4][5][6][7][8][9] In general, bimetallic nanostructures display remarkably improved catalytic activity and selectivity compared with the corresponding monometallic nanocrystals due to the strong ensemble and ligand effects between the different components (that is, geometrical and electronic effects). [4][5][6][7]9 Meanwhile, noble metal nanodendrites with branched arms are attracting tremendous attention for the catalytic applications due to their large surface area, unusual interconnected and porous structure and abundance of low-coordination atoms at steps and corners.…”

“…[4][5][6][7][8][9] In general, bimetallic nanostructures display remarkably improved catalytic activity and selectivity compared with the corresponding monometallic nanocrystals due to the strong ensemble and ligand effects between the different components (that is, geometrical and electronic effects). [4][5][6][7]9 Meanwhile, noble metal nanodendrites with branched arms are attracting tremendous attention for the catalytic applications due to their large surface area, unusual interconnected and porous structure and abundance of low-coordination atoms at steps and corners. 10,11 Consequently, bimetallic noble metal nanodendrites have a broad variety of applications, ranging from organic synthesis to energy conversion.…”

Observation of Skyrmions at Room Temperature in Co2FeAl Heusler Alloy Ultrathin Film Heterostructures

“…The NEXAFS spectra were recorded at soft X-ray beam line 10D KIST beam line 79,80 . The system was evacuated to ~1.5 × 10 −8 Torr.…”

Self‐Assembled Dendritic Pt Nanostructure with High‐Index Facets as Highly Active and Durable Electrocatalyst for Oxygen Reduction

“…[42][43][44][45] The performance of Pt catalysts can be severelyd egraded during the fuel cell operation mainly owing to the loss (dissolution) of Pt nanoparticles, the decrease in the active surface area by Ostwald ripening of the nanoparticles, and the corrosiono fc arbon support materials. [46][47][48][49][50][51][52] Accordingly,t os ecuret he long-term stabilityo fP t-based catalysts, promising synthetic approaches have been extensively proposed. Recently,t he strategies using Pt and PtM alloy nanocrystals with high-index facets have been exploreda st he surfaces tructures have intrinsically unique physical and electrochemical properties.…”