Solution-Grown Dendritic Pt-Based Ternary Nanostructures for Enhanced Oxygen Reduction Reaction Functionality

Abstract

Nanoalloys with anisotropic morphologies of branched and porous internal structures show great promise in many applications as high performance materials. Reported synthetic approaches for branched alloy nanostructures are, however, limited by the synthesis using a seed-growth process. Here, we demonstrate a conveniently fast and one-pot solution-phase thermal reduction strategy yielding nanoalloys of Pt with various solute feed ratios, exhibiting hyperbranched morphologies and good dispersity. When Pt was alloyed with transition metals (Ni, Co, Fe), we observed well-defined dendritic nanostructures in PtNi, PtCo and Pt(NiCo), but not in PtFe, Pt(FeNi) or Pt(FeCo) due to the steric hindrance of the trivalent Fe(acac)3 precursor used during synthesis. In the case of Pt-based nanoalloys containing Ni and Co, the dendritic morphological evolution observed was insensitive to large variations in solute concentration. The functionality of these nanoalloys towards the oxygen reduction reaction (ORR); however, was observed to be dependent on the composition, increasing with increasing solute content. Pt3(NiCo)2 exhibited superior catalytic activity, affording about a five- and 10-fold enhancement in area-specific and mass-specific catalytic activities, respectively, compared to the standard Pt/C nanocatalyst. This solution-based synthetic route offers a new approach for constructing dendritic Pt-based nanostructures with excellent product yield, monodispersity and high crystallinity.

A Novel Au@Cu2O-Ag Ternary Nanocomposite with Highly Efficient Catalytic Performance: Towards Rapid Reduction of Methyl Orange Under Dark Condition

“…Recently, Au, Ag, Pt, and other noble metal nanocatalysts are recognized as promising catalysts for the removal of azo dyes by the virtue of high efficiency [18][19][20]. Among these noble metal nanomaterials, Au nanocrystals have been proven to be the optimal catalysts due to the excellent chemical and physical stability, tunable optical properties, high catalytic performances, and the surface plasmon resonance (SPR) properties [21][22][23][24].…”

Topographical and compositional engineering of core–shell Ni@Pt ORR electro-catalysts

“…This demonstrates that the NPs exhibit a narrow range of orientations, suggesting that templating has occurred: the alignment of new crystals is guided by growth on pre-existing surfaces in a controlled manner. 19 Although low energy {111} crystal facets encase these multiply branched binary alloys, they are high surface area nanostructures. Multiple edges, steps, corners and kinks in addition to densely packed centres dominated the observed symmetrically branched morphologies.…”

“…1,[15][16][17] In this regard, dilution of Pt with 3dtransition metals such as nickel has been successful. [16][17][18][19] Disordered PtNi systems are thought to be key for the development of high performance electrocatalysts: surface defects, terraces, steps and curvatures in these NPs can inuence catalytic performance by exposing crystal facets with undercoordinated atoms. 6,10,16,[20][21][22][23] Common methods to produce metal NPs are wet chemical, vapour deposition, impregnation, solvothermal, pyrolysis, etc.…”

“…16,21,[24][25][26] Of these, wet-chemical synthetic approaches are widely used to prepare monodisperse alloy NPs because they yield uniform sizes, well-dened morphologies and good dispersability in organic solvents. 4,18,19,21,[27][28][29] These structural properties are vital for the utilization of NPs in a wide range of industrial applications. 16,18,21,28,30,31 Optimising the surface structure of NPs for electrocatalysis requires an understanding of the effect of each step in the solution-based synthetic process used.…”

“…The result can be the synthesis of monodisperse alloy NPs with crystallographically complex surface structures and compositional anisotropy within the particles. 4,16,18,19,21,29 Herein, we describe the optimization of several synthesis variables. The outcome of this process is the production of high quality, binary core-shell Ni@Pt NPs from organometallic precursors, reduced by high temperature and by the use of cosurfactants.…”