Nanoalloys and catalytic applications

Nanoscale catalysts derived from noble metals and alloys with other non-noble transition metals have found increasing applications in heterogeneous catalysis, especially in electrocatalytic reactions and gas-phase oxidation reactions. A key challenge is the fundamental understanding of the nanostructures of the catalysts under catalytic or electrocatalytic reaction conditions. This chapter discusses some of the recent insights of investigations into how the phase structures and surface sites of the nanoalloy catalysts operate synergistically in catalytic and electrocatalytic reactions. Examples will highlight nanoalloy catalysts in which a noble metal (e.g., Pt or Pd) is alloyed with a second and/or a third transition metal. One important emphasis is placed on the understanding of atomic-scale phase structure, chemical/structural ordering, and surface oxygenation in correlation with the catalytic or electrocatalytic properties. Findings from ex situ and in situ synchrotron X-ray techniques such as high-energy X-ray diffraction coupled to atomic pair distribution function (HE-XRD/PDF) and X-ray absorption fine structure spectroscopic (XAFS) analysis will be described. Implications of these examples for better design of low-cost, active, and durable catalysts for sustainable energy production and conversion reactions will also be discussed.