Enhancement of Pt Utilization in Electrocatalysts by Using Gold Nanoparticles

摘要

Many important reactions are strongly dependent on noblemetal catalysts, such as electrochemical reactions on the Pt electrode in proton-exchange membrane fuel cells (PEMFC).[1] The development of this promising application has been hampered because of the high cost of the catalyst.[2,3] One way to lower costs is to make the most efficient use of the noble metals so that every metal atom is used in the catalytic process. Because catalysis at the electrode of a fuel cell is a surface phenomenon, the utilization of Pt in electrocatalysts can be defined as the dispersion or exposed percentage of Pt atoms in the catalyst, which is approximately equal to the reciprocal of the Pt particle size in nanometers.[4, 5] According to a number of recent reports, the most favorable particle size for Pt-based electrocatalysts is in the range of 2–4 nm.[6–9] Therefore, the utilization or exposed percentage of Pt atoms in these state-of-the-art electrocatalysts is in the range of 25–50%, far below a 100% utilization or dispersion of the ideal model. To enhance Pt utilization, it would be necessary to further decrease the particle size of Pt-based electrocatalysts.