Hamed Ataee-Esfahani

Nanoarchitectures for Mesoporous Metals.

The field of mesoporous metal nanoarchitectonics offers several advantages which cannot be found elsewhere. These materials have been showcasing impressive enhancements of their electrochemical properties for further implementation, compared to their micro- and macroporous counterparts. Since the last few decades, various methods have been developed to achieve narrow pore size distribution with a tunable porosity and particle morphology. While hard templates offer a reliable and intuitive approach to synthesize mesoporous metals, the complexity of the technique and the use of harmful chemicals pushed several research groups to focus in other directions. For example, soft templates (e.g., lyotropic crystals, micelles assemblies) and solution phase methods (requiring to control reduction reactions) offer more and more possibilities in terms of available compositions and morphologies. Indeed, various metal (Pt, Pd, Au, Ru, etc.) can now be synthesized as dendritic, core@shell, hollow or polyhedral nanoparticles, with single- or multicomponents, alloyed or not, with unprecedented electrochemical activity.

All-metal mesoporous nanocolloids: solution-phase synthesis of core-shell Pd@Pt nanoparticles with a designed concave surface.

Colloidal Pd@Pt nanoparticles with uniform mesopores can be synthesized in one step by a facile solution-phase method involving slow reduction of metal species in strong acidic media. In this system, F127 micelles can directly act as a template to form the mesopores in the product, and the greater reducibility of the Pd species leads to the desired core-shell Pd@Pt nanocolloids.

Synthesis of mesoporous Pt-Ru alloy particles with uniform sizes by sophisticated hard-templating method.

Team work: Mesoporous Pt-Ru alloy particles with uniform sizes are synthesized by controlled chemical reduction with ascorbic acid using mesoporous silica as a hard template. Elemental mapping shows uniform distribution of Pt and Ru particles. The electrochemical activity and stability of the alloys towards methanol oxidation much higher than that of mesoporous Pt and commercial Pt catalyst.

Mesoporous Trimetallic PtPdRu Spheres as Superior Electrocatalysts.

Mesoporous Trimetallic PtPdRu Spheres with well-defined spherical morphology and uniformly sized pores were synthesized in an aqueous solution using ascorbic acid as the reducing agent and triblock copolymer F127 as the pore directing agent. These mesoporous PtPdRu spheres exhibited enhanced electrocatalytic activity compared to commercial Pt black, resulting in a ∼4.9 times improvement in mass activity for the methanol oxidation reaction. The excellent electrocatalytic activity and stability are due to the unique mesoporous architecture and electronic landscape between different elements.