Noble Metal Aerogels: Synthesis and Application as Support-Free Anode Electrocatalysts for Ethanol Electro-Oxidation

Self-sustained metal aerogels are emerging as advanced porous materials with a 3D network of nanostructures that are exclusively made of metals. Metal aerogels possess a distinctive combination of metallic nanoparticles with excellent electronic conductivity, and the excellent porosity of the aerogels allows the extensive exposure of electrocatalytic active sites, together with remarkable mass transport networks in a single entity, unlocking widespread application potential ranging from energy storage and conversion to environmental remediation. In this review, we systematically examine the potential of metal aerogels as electrocatalysts for ethanol electro-oxidation. Various synthesis routes, structure-property relationships, and their function as anode electrocatalysts have been critically reviewed. Due to their 3D porous metallic nature, noble metal aerogel catalysts were found to exhibit excellent ethanol oxidation currents, anti-poisoning for reaction intermediates, high mass, and specific activities of 5-20 times those of traditional Pd/C catalysts. In conclusion, it is shown that metal aerogel catalysts exhibit enhanced activity for ethanol electro-oxidation currents over traditional Pd/C catalysts. Despite this, several challenges exist in realizing the commercial applications of metal aerogels, which have been clearly and elaborately stated as future perspectives and research directions in the field of metal aerogel electrocatalysis.