Tuning the porosity of bimetallic nanostructures by a soft templating approach

TL;DR

This paper presents a soft templating method to synthesize bimetallic palladium-platinum nanoballs with tunable porosity and composition, using oil-swollen surfactant templates to control pore size and nanostructure.

Contribution

The study introduces a novel soft templating approach for controlling porosity and composition in bimetallic nanostructures through templated radiolytic synthesis.

Findings

Pore size is directly controlled by oil tube diameter in the mesophases.

Bimetallic nanoballs with various Pd-Pt ratios can be synthesized.

The nanostructures are composed of interconnected nanowires forming hexagonal cells.

Abstract

We use hexagonal mesophases made of oil-swollen surfactant-stabilized tubes arranged on a triangular lattice in water and doped with metallic salts as templates for the radiolytic synthesis of nanostructures. The nanostructures formed in this type of soft matrix are bimetallic palladium-platinum porous nanoballs composed of 3D-connected nanowires, of typical thickness 2.5 nm, forming hexagonal cells. We demonstrate using electron microscopy and small-angle X-ray scattering that the pore size of the nanoballs is directly determined by the diameter of the oil tube of the doped mesophases, which we have varied in a controlled fashion from 10 to 55 nm. Bimetallic nanostructures comprising various proportions of palladium and platinum can be synthesized. Their alloy structure was evidenced by X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, and high-angular dark field scanning transmission electron microscopy experiments. Our templating approach allows therefore the synthesis of bimetallic nanoballs of tunable porosity and composition.