Synthesis of 3D Porous Nanostructured Platinum Using Atomic Layer Deposition

Abstract

Platinum is known for its catalytic efficiency, exceptional electrical and electrochemical properties, and high resistance to corrosion. Pt nanostructures exposing large surface areas are widely used in catalytic converters, chemical production, and gas sensing and energy conversion technologies. Engineering porosity into Pt nanomaterials is an explored route to maximize the surface over volume ratio and to enhance the performance while reducing the Pt content and cost. It is well established that the properties of 3D-structured Pt nanomaterials are closely related to their geometrical configuration. Synthesis approaches that can produce well-defined porous Pt nanostructures are therefore attractive. Here, we present the creation of micrometer sized porous Pt nanostructures using atomic layer deposition (ALD) [1]. Robust and easy to handle porous Pt is fabricated by replication of an ordered mesoporous silica with a special pore architecture. After ALD of Pt in the unique 3D channel system of the silica material and digestion of the template, a fully connected ordered porous Pt network is obtained with a 3D structure corresponding to that of the host matrix, as revealed with high-resolution scanning transmission electron microscopy and electron tomography. The Pt nanostructure consists of hexagonal Pt rods (with a diameter of ca. 11 nm) originating from the straight mesopores of the host structure and linking features resulting from Pt replication of interconnecting slits. The Pt replica is evaluated for its potential use as electrocatalyst for the hydrogen evolution reaction (HER), one of the half-reactions of water electrolysis. The high activity displayed by the material is attributed to the 3D ordered, mesoporous structure with large surface area.