Recent Progress of Ultrathin 2D Pd-Based Nanomaterials for Fuel Cell Electrocatalysis.

Pd- and Pd-based catalysts have emerged as potential alternatives to Pt- and Pt-based catalysts for numerous electrocatalytic reactions, particularly fuel cell-related reactions, including the anodic fuel oxidation reaction (FOR) and cathodic oxygen reduction reaction (ORR). The creation of Pd- and Pd-based architectures with large surface areas, numerous low-coordinated atoms, and high density of defects and edges is the most promising strategy for improving the electrocatalytic performance of fuel cells. Recently, 2D Pd-based nanomaterials with single or few atom thickness have attracted increasing interest as potential candidates for both the ORR and FOR, owing to their remarkable advantages, including high intrinsic activity, high electron mobility, and straightforward surface functionalization. In this review, the recent advances in 2D Pd-based nanomaterials for the FOR and ORR are summarized. A fundamental understanding of the FOR and ORR is elaborated. Subsequently, the advantages and latest advances in 2D Pd-based nanomaterials for the FOR and ORR are scientifically and systematically summarized. A systematic discussion of the synthesis methods is also included which should guide researchers toward more efficient 2D Pd-based electrocatalysts. Lastly, the future outlook and trends in the development of 2D Pd-based nanomaterials toward fuel cell development are also presented.