Touch Of Gold Makes Catalyst Shine

A smattering of gold atoms and some heat are all it takes to transform iron-platinum nanoparticles into the most efficient nanoparticle catalyst ever reported for the formic acid oxidation reaction—the anode reaction that powers direct formic acid fuel cells (J. Am. Chem. Soc., DOI: 10.1021/ja300708j). Shouheng Sun, of Brown University, and coworkers found that gold helps shift the atoms’ arrangement. As prepared, the atoms in the 4-nm FePtAu particles are distributed randomly with a face-centered cubic structure. Upon annealing at 600 °C, the gold migrates to the outer surface of the nanoparticles, leaving behind enough space for the iron and platinum to take on a more organized face-centered tetragonal structure. This restructured particle turns out to be superb at catalyzing the formic acid oxidation reaction. The fuel-cell current generated by using the restructured catalyst particles turns out to be the highest, on a per milligram of Pt basis, among all nanoparticle catalysts reported, according to the team. Also, the gold gobbles up carbon monoxide that would otherwise poison the catalyst, so it maintains more than 90% of its activity after 13 hours of operation. The researchers believe the structure control strategy could provide a general approach to making nanoparticle catalysts with improved activity and durability.