A paradigm shift in CO tolerant catalyst design for fuel cells via introducing defect-controlled carbon molecular sieve layers

Abstract

The CO poisoning effect leads to serious performance degradation of polymer electrolyte membrane fuel cells using reformed H2 as fuel. To address this problem, PtRu-based catalysts have been extensively studied over decades. Nevertheless, the catalyst stability issue due to Ru dissolution has always risen to the surface. Here, we propose a solution to simultaneously achieve high CO tolerance and stability of PtRu catalysts via introducing a defect-controlled carbon molecular sieve layer. The ultrathin carbon shell with controlled pore structures allows for the selective permeation of H2, providing exceptionally high CO tolerance. The molecular sieve effect is demonstrated even by Ru-free Pt nanoparticles with carbon shells. The carbon shell-encapsulated PtRu nanoparticles also show remarkably improved stability due to the protective carbon layer. This atomic-scale molecular sieve effect is expected to bring about a radical change in the design of CO tolerant catalyst structures that have been entirely dependent on metal composition.