CO-tolerant PtRu@h-BN/C core–shell electrocatalysts for proton exchange membrane fuel cells

•PtRu nanoparticles in commercial PtRu/C catalysts have been well encapsulated by few-layer h-BN shells.•PtRu@h-BN/C catalysts exhibit enhanced CO-tolerance ability in fuel cells, higher resistance to particle sintering, and suppressed carbon oxidation.•The improved performance of the PtRu@h-BN/C catalyst can be attributed to the confinement effect of the h-BN outer shells.