Sulfur-functionalized carbon aerogels: a new approach for loading high-surface-area electrode nanoarchitectures with precious metal catalysts

Thiophene-modified resorcinol–formaldehyde (RF) aerogels are prepared using a two-stage reaction sequence. Resorcinol–formaldehyde gels are generated in the first step using conventional sol–gel methods, followed by a second reaction stage in which the partially cured RF gel is reacted with 3-thiophenecarboxaldehyde before aerogel processing. Heterocyclic sulfur is retained in the aerogel following pyrolytic conversion of the insulating polymeric aerogel to its conductive carbon form, as shown by X-ray photoelectron spectroscopy. The ability of this sulfur-functionalized carbon aerogel to mimic the thiophene-mediated precious metal binding that occurs with Vulcan carbon was investigated by adsorbing pre-formed Pt metal colloids from aqueous colloidal suspensions, when unmodified carbon aerogels exhibit minimal uptake of Pt. The Pt-loaded, sulfur-functionalized carbon aerogels are characterized electrochemically by CO-stripping voltammetry and examined for oxygen reduction activity. The results suggest that these functionalized nanoarchitectures may improve the applicability of carbon aerogel electrode structures for fuel cell and other electrocatalytic applications.