Recent progress in Pt and Pd-based hybrid nanocatalysts for methanol electrooxidation

Although Pt and Pd nanocrystals are among the most popular candidates for anode catalysts in direct methanol fuel cells, their catalytic properties still need to be further improved in order to reduce the costs. In view of this, fabricating hybrid nanomaterials by integrating noble metal nanocrystals and other species turns out to be a powerful way to produce unprecedented catalysts which could combine the merits of different components and modulate the electronic states of Pt or Pd at the same time. In this review, we list recent studies in the construction of heterostructured hybrid nanocatalysts through introducing external components into the noble metal nanocrystals. The mentioned external components include heteroatom doped carbon nanomaterials, metal oxides and hydroxides, as well as transition metal carbides, nitrides, phosphides, and sulfides. The construction methodologies and functions that these introduced species played in the catalytic processes of methanol electrooxidation are discussed. The attempts to maximize the catalytically active interfaces and utilization efficiencies of noble metals are also presented. Finally, the conclusions and existing problems in relevant nanocatalysts are provided.