Improved activity and stability of dealloyed bimodal nanoporous PtCo catalysts for CO oxidation

Abstract

We reported the superior catalytic performance of bimodal nanoporous PtCo (np-PtCo) catalysts towards CO oxidation at low temperature. The np-PtCo catalysts prepared by a multiphase dealloying process consist of parallel pillar-channel nano-arrays around hundreds of nanometers, in which the pillars are composed of a bicontinuous interpenetrating ligament-pore structure with sizes down to 3 nm. This unsupported nanoporous bimetallic catalyst shows remarkable improved catalytic activity and stability compared with either PtCo nanoparticles or a nanoporous Pt catalyst. A very low apparent activation energy (28.3 kJ mol⁻¹) for CO oxidation over np-PtCo was measured. At the operation temperature of proton exchange membrane fuel cells (PEMFCs 80 °C), a CO conversion higher than 99.5% was sustained for more than 20 h. The superior activity and stability can be attributed to its bimodal nanoporous structure and the Pt–Co synergistic effect.