Synthesis of hierarchical metal nanostructures with high electrocatalytic surface areas

Abstract

3D interconnected structures can be made with molecular precision or with micrometer size. However, there is no strategy to synthesize 3D structures with dimensions on the scale of tens of nanometers, where many unique properties exist. Here, we bridge this gap by building up nanosized gold cores and nickel branches that are directly connected to create hierarchical nanostructures. The key to this approach is combining cubic crystal–structured cores with hexagonal crystal–structured branches in multiple steps. The dimensions and 3D morphology can be controlled by tuning at each synthetic step. These materials have high surface area, high conductivity, and surfaces that can be chemically modified, which are properties that make them ideal electrocatalyst supports. We illustrate the effectiveness of the 3D nanostructures as electrocatalyst supports by coating with nickel-iron oxyhydroxide to achieve high activity and stability for oxygen evolution reaction. This work introduces a synthetic concept to produce a new type of high-performing electrocatalyst support.

Controlling Platinum Active Sites on Silver Nanoparticles for Hydrogen Evolution Reaction

“…The Pt decoration on Ag was then carried out via the thermal decomposition of a Pt precursor. A low concentration of Pt­(acac) 2 was used in the reaction with H 2 as a mild reducing agent and TOP as a strong binding surfactant. , The reaction was carried out at 40 °C, which is a mild temperature in a seed-mediated synthesis to ensure slow formation and deposition of Pt monomers to favor heterogeneous growth of Pt on the surface of Ag rather than homogeneous nucleation of Pt nanoparticles. − …”

Three-dimensional nanoscale metal, metal oxide, and semiconductor frameworks through DNA-programmable assembly and templating

“…Modern technological advances in electronics, photonics, and sensing rely heavily on planar fabrication approaches offered by top-down lithographic methods ( 1 ). However, in a broad range of emerging applications in optical and mechanical metamaterials, neuromorphic computing and energy materials require three-dimensional (3D) framework organization with complex material compositions and controllable nanoscale architecture ( 2 – 4 ). Additive manufacturing provides a route for fabricating 3D structured metals at the microscales ( 5 ).…”

The fractal geometry of polymeric materials surfaces: surface area and fractal length scales

“…Nanostructures, metamaterials, and hierarchical structures have attracted a great deal of attention due to their applications in a variety of fields such as sensors, 1,2 photoelectronic devices, 3 catalysis, 4,5 water splitting, 6 and energy, [7][8][9][10][11][12] just to name a few. Indeed, multiscale structures are one of the dominant themes in current experimental studies, 13,14 which include Nature-inspired designs for the manufacture of new hierarchical nanostructures, [15][16][17] and the fabrication of promising composite materials.…”