Regulating Surface Facets of Metallic Aerogel Electrocatalysts by Size-Dependent Localized Ostwald Ripening

It is well known that the activity and stability of electrocatalysts are largely dependent on their surface facets. In this work, we have successfully regulated surface facets of three-dimensional (3D) metallic Aum-n aerogels by salt-induced assembly of citrate-stabilized gold nanoparticles (Au NPs) of two different sizes and further size-dependent localized Ostwald ripening at controlled particle number ratios, where m and n represent the size of Au NPs. In addition, 3D Aum-n–Pd aerogels were further synthesized on the basis of Aum-n aerogels and also bear controlled surface facets because of the formation of ultrathin Pd layers on Aum-n aerogels. Taking the electrooxidation of small organic molecules (such as methanol and ethanol) by the resulting Aum-n and Aum-n–Pd aerogels as examples, it is found that surface facets of metallic aerogels with excellent performance can be regulated to realize preferential surface facets for methanol oxidation and ethanol oxidation, respectively. Moreover, they also ind...