Ultralong (∼25–30 μm) surface-Pt-rich Au93Pt7 alloy nanowires (ANWs) were achieved by a directional coalescence between spherical nanoparticles. Also, the ANWs exhibit superior electrocatalytic activity and long-term durability towards ethanol oxidation, ∼12 times in the mass activity better than the state-of-the-art commercial Pt/C catalyst.

•Glycine-directed electrochemical growth of 3D Au nanostructure (3DGN) was achieved.•3DGN consists of four-fold symmetric fern-like dendrites.•Each Au dendrite is a single-crystal growing along the (111) direction.•3DGN shows enhanced catalytic activity and durability towards methanol oxidation.Hierarchical nanostructures are very universal in the natural world. However, to date most of synthetic approaches are just capable of producing simple nanomaterials, such as nanospheres, nanorods, nanowires, nanopolyhedrons, etc. Fabrication of complex nanostructures has to depend on the assembly of single nano-building blocks and e-beam lithography. Thus, it is imperative to create complex nanostructures by direct synthetic methods. Herein, three-dimensional fern-like Au nanostructures (3DFGNs) were achieved simply by one-step glycine-assisted electrodeposition. The effects of glycine concentration, electrode substrate and deposition potential on the growth of Au nanostructures were explored. Over the range of glycine concentration from 1.0 mmol/L to 10 mmol/L, all Au nanostructures are 3DFGNs except for the difference of the average diameter of branches. The oriented growth of 3DFGN is attributed to the specific adsorption of NH2 groups of glycine. Each fern-like dendrite of 3DFGN is a four-fold symmetric single-crystal growing along the (111) direction. As-prepared 3DFGNs show morphology- and size-dependent electrocatalytic performance towards methanol oxidation. Optimized 3DFGN exhibits satisfactory electrocatalytic activity and long-term durability, ∼3 times in the specific activity better than island-like Au aggregates electrodeposited without glycine.

Bimetallic catalysts, PtBi, PtPd and PdBi have been explored and may be promising candidates for next-generation anodic catalysts of direct alcohol fuel cells due to their enhanced catalytic activity and long-term durability. However, ternary PtPdBi alloy catalysts are rarely reported because of the synthetic difficulty in manipulating three metallic precursors. Here, ternary metallic PtxPd93−xBi7 alloy nanowires were prepared for systematically investigating their electrocatalytic activity towards ethanol oxidation in basic solution by cyclic voltammetric and amperometric techniques. PtxPd93−xBi7 alloy nanowire, whether loaded on Vulcan XC72 carbon (C) or reduced graphene oxide (RGO), has better catalytic activity than PtPd, PtBi, PdBi, Pt/C, or Pd catalyst. Nevertheless, the catalytic activity of PtxPd93−xBi7 closely depends on the Pt:Pd atomic ratio. Pt55Pd38Bi7 alloy nanowire with the optimal Pt:Pd atomic ratio can produce the maximum enhancement towards ethanol electrooxidation. RGO replacing C as catalyst supporter can further improve the catalytic performance of catalyst. Pt55Pd38Bi7/RGO exhibits a superior catalytic performance, the mass activity of which reaches ∼3.60 A mg−1, ∼6 times better than commercial Pt/C.

Three-dimensional (3D) porous Au nanocoral network (GNN) structure was fabricated on glassy carbon (GC) electrode by one-step, template-free electrodeposition and decorated with ultrathin Pt film by combining the underpotential deposition (UPD) of copper adatoms and the galvanic displacement (GD) between PtCl62- and Cu. The thickness of Pt atomic layers can be controlled precisely by repeating the UPD–GD process. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) were employed to characterize the morphology of GNN and Ptn/GNN (n, the cycles of repeating the UPD–GD process). Cyclic voltammometric and chronoamperometric tests indicate that all Ptn/GNN samples effectively support the direct oxidation of formic acid and show higher electrocatalytic performance than the commercial Pt/C catalyst (Pt, 20 wt %, Johnson Matthey Co.), where Pt1/GNN completely eliminates the indirect oxidation of formic acid, exhibiting the best electrocatalytic activity and stability among all Ptn/GNN samples due to the optimal coverage and distribution of Pt atoms on GNN.

Owing to the high hydrophobicity of the graphene surface and the easy aggregation of Pt nanoparticles, it is very challenging to deposit high loading and a uniform distribution of Pt nanoparticles on graphene nanosheets. Herein, we report a facile approach to produce nanocomposites of Pt nanoparticles and reduced graphene oxide (Pt/RGO) with the intervention of glucose. The number density and arrangement of Pt nanoparticles on RGO nanosheets can be adjusted simply by changing the amount of Pt precursors. With the increase of the amount of Pt precursors, the loading amount of Pt nanoparticles rises and simultaneous Pt nanoparticle arrangement evolves from sparse distribution to a close-packed monolayer, to linear aggregation. HRTEM reveals that Pt nanoparticles are (111)-orientated nanocrystals (NCs) close to 3 nm. Pt24/RGO (Pt, 24 wt%) holds an excellent catalytic performance and stability towards methanol oxidation, ∼3 times in the mass activity better than the commercial Pt/C catalyst (Pt, 20 wt%), due to the close-packed monolayer structure of Pt NCs.

The electrochemical preparation of non-carbon supported catalysts is a favourable way for fuel cells to keep catalysts from agglomerating during the electrocatalytic process and provide the catalyst layer with higher mechanical stability than the established drop-coating deposition of a mixture of catalysts and carbon powder. Herein, one-step current-directed approach is proposed to fabricate 3-dimensional (3D) Pt hierarchical nanostructures (3DPHNs) without any capping agents. The resulting 3DPHNs were composed of Hydrangea macrophylla flower-like Pt microspheres, and each microsphere consisted of several nano-petals. The size, the number density and the exposed facets of Pt microspheres in 3DPHNs can be adjusted by changing the current density of Pt deposition. High-resolution transmission electron microscopy (HRTEM) revealed that Pt nano-petals obtained at deposition current densities higher or lower than 3.5 mA cm−2 contained Pt{200} and Pt{111} facets. However, Pt nano-petals obtained at 3.5 mA cm−2 were single crystals with {111} orientation that showed better specific catalytic activity and stability to methanol electrooxidation compared to commercial Pt/C catalyst due to its resistance to catalyst agglomeration and the exposure of specific facets and the specific nanostructure.

•Au nano-coral (3DGN) was electrodeposited simply with the guidance of NH4+NH4+.•3DGN was able to be decomposed into individual (111)-orientated Au nanocrystals.•This technique provides a way to produce (111)-orientated Au nanocrystals.•Optimized 3DGN exhibits intense enhancement and reproducibility of SERS.In this work, a reliable surface-enhanced Raman scattering (SERS)-active substrate, three-dimensional gold nano-coral structure (3DGN), was prepared simply by one-step electrodeposition in HAuCl4 and NH4Br solution without the confinement of templates or the guidance of organic surfactants. The final morphology and thickness of 3DGN depend on the concentration of NH4Br and the electrodeposition time. When the concentration of NH4Br was 10.0 mmol/L, as-prepared 3DGN has a uniform structural morphology and exhibits the best SERS activity, spatial uniformity and reproducibility towards rhodamine 6G (R6G). The relative standard deviation (RSD) of the spot-to-spot SERS signals is about 10% according to the intensity of 1506 cm−1 Raman vibration modes of R6G, meeting the requirement of SERS substrate for analytic detection. Additionally, the resulting 3DGN could be decomposed into individual (111)-orientated Au nanocrystals under ultrasonication, providing a facile approach to produce Au nanocrystals.

Ultralong (∼25–30 μm) surface-Pt-rich Au93Pt7 alloy nanowires (ANWs) were achieved by a directional coalescence between spherical nanoparticles. Also, the ANWs exhibit superior electrocatalytic activity and long-term durability towards ethanol oxidation, ∼12 times in the mass activity better than the state-of-the-art commercial Pt/C catalyst.

Three-dimensional (3D) cubic superstructures of PtPd nanocubes were achieved by spontaneous adjustment of PtIV reduction kinetics, and exhibited enhanced catalytic activity and long-term durability towards methanol oxidation compared with the state-of-the-art Pt/C. This work demonstrates the first example of designing 3D shaped architectures of PtPd nanocubes for methanol electrooxidation.