Stabilized Nanoporous Metals By Dealloying Ternary Alloy Precursors

摘要

Porous precious metals with pore size distributions centered below 5 nm are useful for applications in electrocatalysis, sensing, and others, where the combination of high surface area and electric contact to all surface sites is advantageous. Such materials possess the virtues of nanoparticles with their good surface-area-to-volume ratio and few of their downsides, for example, there are no supports to corrode or de-adhere from and particle sintering would not lead to a reduction in surface area. A few methods have been developed to make porous precious metals with pore sizes below 5 nm. One method is templated growth, plating into the interstices of a porous parent phase that is later removed. A different method -dealloying - is receiving increased attention recently because of its ease in processing. One starts with a monolithic alloy in any form factor, such as bulk or thin film, and selectively electrochemically dissolves the less-noble component of the alloy. Here, we demonstrate that small fractions of Pt added to precursor Ag/Au alloys result in a new ultraporous metal upon dealloying, possessing a pore size peaked at less than 4 nm, a self-assembled core/shell structure, and remarkable stability against coarsening.