Pd-based intermetallic nanocrystals: From precise synthesis to electrocatalytic applications in fuel cells

In recent years, Pd-based intermetallic nanocrystals (INCs) have attracted widespread attention as electrocatalysts for fuel cells. The definite composition and predictable control over structural, geometric and electronic effects of Pd-based INCs endow them outstanding catalytic activity and high stability. Here, we present a comprehensive review about recent research progress of Pd-based INCs as catalysts for fuel cells. Firstly, we summarize the synthetic methods of Pd-based INCs with fixed stoichiometry and ordered atomic structure, such as thermal annealing, wet-chemical method. In particular, the control of morphology, size and crystal structure of Pd-based INCs is emphasized. Secondly, we highlight the applications of Pd-based INCs for electrocatalytic reactions in fuel cells, including oxygen reduction reaction, methanol oxidation reaction, ethanol oxidation reaction and formic acid oxidation reaction. The strategies for improving the electrocatalytic performance of Pd-based INCs are systematically discussed. Finally, the existing challenges and promising future research directions in this field are proposed.