Department of Chemical and Biological Engineering2024-11-0920201615-684610.1002/fuce.2019000872-s2.0-85074809923http://dx.doi.org/10.1002/fuce.201900087https://hdl.handle.net/20.500.14288/13561Carbon aerogel and Vulcan supported PtCu electrocatalysts were prepared using the simultaneous and sequential in situ supercritical deposition (SCD) method in supercritical CO2 followed by thermal annealing and electrochemical dealloying. Before dealloying, annealed electrocatalysts prepared by simultaneous SCD had a more uniform PtCu composition in PtCu nanoparticles whereas electrocatalysts prepared by sequential SCD led to PtCu nanoparticles with Cu enrichment on the surface. Upon dealloying, PtCu/CA electrocatalyst prepared by simultaneous SCD had an enhanced ESA of 159.4 m(2) g(-1) due to the synergistic effects of PtCu nanoparticle size and PtCu composition in nanoparticles. All dealloyed electrocatalysts had higher mass activities and PtCu/Vulcan electrocatalyst prepared by simultaneous SCD had the highest mass activity of 0.178 A mg(Pt)(-1) which was more than twice of the mass activity of commercial Pt/C. PtCu/Vulcan electrocatalyst prepared by sequential SCD showed a specific activity of 0.511 mA cm(-2) which was 5 times higher than the specific activity of commercial Pt/C.ElectrochemistryEnergyFuelsJournal Article1615-6854494540500001747