Hierarchical Nanoporous Carbon Materials as Active Support of Electrocatalytic Nanoparticles

BARBERO C. A.; BAENA MONCADA, A. M.; RUSBEL CONEO RODRÍGUEZ; PLANES G. A.; ACEVEDO D. F.

Lausanne

Congreso; The 65th Annual Meeting of the International Society of Electrochemistry; 2014

International Society of Electrochemistry (ISE)

Fuel cell electrodes are made of catalytic nanoparticles supported on different kinds of carbon.[1] While commercial (e.g. Vulcan XC72) carbon are usually used, carbon materials with a more controlled porosity could have better perfomance.[2] It has been shown that hierarchical nanoporous carbon (HnPC) materials could be synthesized using a hard template method, which can be used as support of PtRu nanoparticles.[3] In the present communication, we describe the synthesis of different HnPCs and its use as support of electrocatlytic nanoparticles. The three dimensional carbon porosity is examined using focused ion beam combined with scanning electron microscopy (FIBSEM). The electrochemical properties of the HnPCs are studied using cyclic voltammetry, AC impedance, chronoamperometry and Probe Beam Deflection (PBD).[4] Chronoamperometry and AC impedance measurements of HnPC seems to fit a transmission line model. PBD data show evidence of local pH changes inside the pores, during double layer charging.The HnPCs are used as active support for metal (Pt/Ru and Pt/Pd) nanoparticles.Additionally, Pt decorated magnetite (Fe3O4) nanoparticles are produced inside the HnPC by galvanic displacement. The materials are used for the electrocatalysis of the oxidation/reduction of different reactants (CO, HCOOH, CH3OH, O2). The electrocatalytic activity is measured using rotating disk voltammetry. A catalyst made by chemical deposition of PtPd nanoparticles on a HnPC300 (produced using 300 nm silica nanoparticles), present better perfomance for HCOOH and CH3OH oxidation than a commercial (ETEK) catalyst.The electrodes made with FePt nanoparticles show good activity for oxygen reduction reaction (ORR), while having a high tolerance to methanol.Both in the case of PtPd and FePt based electrocatalysts, the nanoparticles supported on HPC present higher activity than those deposited on planar glassy carbon. The electrocatalytic activity increases when the pore size is diminished.