Construction of Concave PdAg Nanoshells with Limited Thickness for Efficient Electroxidation of Ethanol

Noble metal nanocrystals enclosed with curved surfaces are of great benefit for applications in electrocatalysis since the atomic steps and kinks on these facets have higher chemical activity. Herein, we report the fabrication of PdAg nanoshells with tunable thickness in the range of 5–13 nm and a unique concave cubic morphology, as well as the exploration of their applications for ethanol oxidation reaction (EOR) in alkaline media. The success of current work relies on the conformal deposition of PdAg on concave Au nanocubes, where the controlled reaction kinetics and proper chosen capping agent are both crucial for the growth mode. When loaded on carbon black and working as electrocatalysts, they exhibited superb electrochemical activity (e.g., 600.21 mA mg−1 in mass activity and 19.57 A m−2 in specific activity), together with improved EOR kinetics and long-term durability, as compared to Au@Pd nanoparticles and commercial Pd/C. The current work offers a feasible strategy to produce PdAg bimetallic nanocrystals with concave surface and validates their promising application as fuel cell catalysts, which could be extended to morphology engineering of other noble-metal nanocrystals for a broad range of applications.

Bimetallic Nanocrystals: Structure, Controllable Synthesis and Applications in Catalysis, Energy and Sensing

In recent years, bimetallic nanocrystals have attracted great interest from many researchers. Bimetallic nanocrystals are expected to exhibit improved physical and chemical properties due to the synergistic effect between the two metals, not just a combination of two monometallic properties. More importantly, the properties of bimetallic nanocrystals are significantly affected by their morphology, structure, and atomic arrangement. Reasonable regulation of these parameters of nanocrystals can effectively control their properties and enhance their practicality in a given application. This review summarizes some recent research progress in the controlled synthesis of shape, composition and structure, as well as some important applications of bimetallic nanocrystals. We first give a brief introduction to the development of bimetals, followed by the architectural diversity of bimetallic nanocrystals. The most commonly used and typical synthesis methods are also summarized, and the possible morphologies under different conditions are also discussed. Finally, we discuss the composition-dependent and shape-dependent properties of bimetals in terms of highlighting applications such as catalysis, energy conversion, gas sensing and bio-detection applications.

Highly Porous Au–Pt Bimetallic Urchin-Like Nanocrystals for Efficient Electrochemical Methanol Oxidation

Highly porous Au–Pt urchin-like bimetallic nanocrystals have been prepared by a one-pot wet-chemical synthesis method. The porosity of urchin-like bimetallic nanocrystals was controlled by amounts of hydrazine used as reductant. The prepared highly porous Au-Pt urchin-like nanocrystals were superior catalysts of electrochemical methanol oxidation due to high porosity and surface active sites by their unique morphology. This approach will pave the way for the design of bimetallic porous materials with unprecedented functions.

Ir-Ni based mono and bimetallic nanocrystals: synthesis, characterization and effect of cationic, anionic, and non-ionic stabilizers

Nickel based bimetallic nanocrystals, iridium-nickel play an imperative role in catalysis, electrocatalysis, and magnetic applications. In the present work Ir-Ni bimetallic nanoalloys were synthesized by modified polyol reduction method with different cationic, anionic, and non-ionic surface active agents like CTAB, SDS, TSC, and PVP. The non-ionic surface active agent PVP produced a better effect on nanoparticle size than cationic and anionic surfactants. The synthesized bimetallic nanocrystals were characterized by UV-Vis, XRD, FTIR, FESEM, and HRTEM techniques. XRD and FTIR verify the nature of synthesized bimetallic nanocrystals and the interaction between stabilizers and nanoparticles. HRTEM studies reveal that the PVP stabilized Ir-Ni (3:1) and Ir-Ni (1:1) bimetallic nanocrystals are small in size and less dispersed. Particle size range of these nanoparticles is from (1.77-2.36) nm. FESEM images show that nanoparticles are in quasi spherical shape. EDX analysis indicates that the resultant particles are core shell structure with Ni core and Ir shell.

Laser assisted synthesis of anisotropic metal nanocrystals and strong light-matter coupling in decahedral bimetallic nanocrystals

The advances in colloid chemistry and nanofabrication allowed us to synthesize noble monometallic and bimetallic nanocrystals with tunable optical properties in the visible and near infrared region of the electromagnetic spectrum.

Fabrication and Characterization of Biplasmonic Substrates Obtained by Picosecond Laser Pulses

Bimetallic nanostructures have the potential to become the new generation candidates for applications in catalysis, electronics, optoelectronics, biosensors and also for surface-enhanced Raman Spectroscopy (SERS). The bimetallic nanocrystals offer additional properties over the single metal components such as improved electromagnetic properties and corrosion protection. This work presents a simple and inexpensive method to fabricate large area biplasmonic (bimetallic) substrates, employing DC magnetron sputtering, picosecond laser pulses and a digital galvanometric scanner. The aim of this study was to achieve large area homogeneous substrates while having a good and predictable signal amplification by SERS effect. Gold thin films with 200 nm thickness were deposited on optical polished substrates and then irradiated in atmospheric air with λ = 1064 nm wavelength laser pulses with 8 ps pulse duration and 500 kHz fixed repetition rate. Various laser fluences and laser irradiation speeds were employed in order to optimize the Laser-Induced Periodic Surface Structures (LIPSS) formed on the substrate. The results are presented comparatively for the standalone Cu substrates and for the Cu-Au substrates using Raman spectral analysis on a single signal peak of a Rhodamine 6G solution.