Polyamide aerogel-derived n-doped carbon aerogel decorated with platinum nanoparticles as highly active and stable electrocatalysts for oxygen reduction reaction

Abstract

We prepared polyamide aerogel (PA)-derived carbon aerogel (CA) supported Pt nanoparticles with the super-critical CO2 deposition (SCD) technique as electrocatalysts for the oxygen reduction reaction (ORR). PAs were pyrolyzed at 800 degrees C to yield CPA and some CPA monoliths were subsequently etched with CO2 at 1000 degrees C to yield etched CPA (ECPA) to increase micro-mesoporosity and surface area in order to investigate their effect on the Pt nanoparticle dispersion and electrocatalytic performance towards ORR. The N-rich backbone of PAs yielded homogenously distributed N atoms in the CA structure enabling homogenous distribution of Pt nano-particles, efficient dispersion of the Nafion ionomer and possible creation of ORR-active sites. Highly dispersed Pt nanoparticles with average size of 1.5 and 3.0 nm were obtained on CPA and ECPA, respectively. Pt-ECPA electrocatalysts showed enhanced electrochemically active surface area (ESA) and ORR mass activity when compared with commercial Pt-C. Pt-CPA showed similar ESA, mass and specific activity to that of commercial Pt-C due to lower mesopore volume and higher average Pt nanoparticle size. Accelerated stability tests (AST) revealed superior stability of Pt-CPA electrocatalyst due to favorable initial Pt nanoparticle size enabling suc-cessful immobilization Pt nanoparticles on CPA through the N-functionalities. Two important parameters, pore structure of carbon aerogel and initial Pt nanoparticle size, can be controlled through the powerful combination of sol-gel and supercritical deposition techniques to achieve both highly active and stable electerocatalysts.