Composition optimized trimetallic PtNiRu dendritic nanostructures as versatile and active electrocatalysts for alcohol oxidation

Platinum-based nanocrystals are the most effective electrocatalysts for accelerating the chemical transformations on the anode in direct alcohol fuel cells. To facilitate practical applications and overcome the drawbacks of diverse alcohols, it is significant to develop electrocatalysts with high activities and a wide fuel flexibility. Here, we demonstrate a practicable solution method for fabricating composition tunable trimetallic PtNiRu dendritic nanostructures (DNSs) which can serve as versatile and active catalysts for electrooxidation of a variety of liquid alcohols. A series of trimetallic DNSs with tunable Pt/Ni/Ru atomic ratios were successfully synthesized by simply adjusting the feeding of precursors. Detailed electrochemical test indicates that, among other compositions, the Pt₆₆Ni₂7Ru7 DNSs present much superior electroactivity in catalyzing electrooxidation of liquid alcohols in acidic mediums. Specifically, the mass activity and specific activity on the Pt₆₆Ni₂₇Ru₇ DNSs, for electrooxidation of methanol, ethanol, and ethylene glycol, are 4.57 and 4.34 times, 3.55 and 3.42 times, and 2.37 and 2.28 times that of the commercial Pt black, respectively. X-ray photoelectron spectroscopy and CO stripping studies reveal the adsorption of CO on these PtNiRu DNSs is much weaker than on pure Pt. Meanwhile, the surface Ru sites can provide neighbouring -OH groups to facilitate the oxidation and removal of the adsorbed intermediates (-CO) on the surface Pt sites, effectively improving the CO tolerance of the catalysts. The PtNiRu DNSs also show effectively boosted capacity for breaking the C-C bond in C₂-alcohols, showing great potential for fuel-flexible fuel cell applications.