Affiliation:
1. School of Chemical and Biomolecular Engineering The University of Sydney Darlington New South Wales 2006 Australia
2. Advanced Institute for Materials Research (WPI‐AIMR) Tohoku University Sendai 980–8577 Japan
Abstract
AbstractPlatinum‐Ruthenium (PtRu) bimetallic nanoparticles are promising catalysts for methanol oxidation reaction (MOR) required by direct methanol fuel cells. However, existing catalyst synthesis methods have difficulty controlling their composition and structures. Here, a direct Joule heating method to yield highly active and stable PtRu catalysts for MOR is shown. The optimized Joule heating condition at 1000 °C over 50 microseconds produces uniform PtRu nanoparticles (6.32 wt.% Pt and 2.97 wt% Ru) with an average size of 2.0 ± 0.5 nanometers supported on carbon black substrates. They have a large electrochemically active surface area (ECSA) of 239 m2 g−1 and a high ECSA normalized specific activity of 0.295 mA cm−2. They demonstrate a peak mass activity of 705.9 mA mgPt−1 for MOR, 2.8 times that of commercial 20 wt.% platinum/carbon catalysts, and much superior to PtRu catalysts obtained by standard hydrothermal synthesis. Theoretical calculation results indicate that the superior catalytic activity can be attributed to modified Pt sites in PtRu nanoparticles, enabling strong methanol adsorption and weak carbon monoxide binding. Further, the PtRu catalyst demonstrates excellent stability in two‐electrode methanol fuel cell tests with 85.3% current density retention and minimum Pt surface oxidation after 24 h.
Funder
National Computational Infrastructure
Australian Research Council