TY - JOUR
T1 - Scalable Synthesis of Carbon-Supported Platinum–Lanthanide and −Rare-Earth Alloys for Oxygen Reduction
AU - Roy, Claudie
AU - Knudsen, Brian P.
AU - Pedersen, Christoffer M.
AU - Velazquez-Palenzuela, Amado
AU - Christensen, Leif H.
AU - Damsgaard, Christian Danvad
AU - Stephens, Ifan E. L.
AU - Chorkendorff, Ib
PY - 2018
Y1 - 2018
N2 - Platinum–rare-earthalloys have proven to be both active and stable under accelerated stability tests in their bulk polycrystalline form. However, a scalable method for the synthesis of a high-surface-area supported catalyst of these alloys has so far not been presented. Herein we discuss the thermodynamics relevant for the reduction conditions of the rare earths to form alloys with platinum. We show how the tolerance for water and oxygen severely limits the synthesis parameters and how under certain conditions the thermal reduction of YCl3 with H2 is possible from 500 °C. From the insight gained, we synthesized a PtxY/C catalyst by modifying a Pt/C catalyst and confirmed alloy formation by both X-ray diffraction and X-ray photoelectron spectroscopy measurements.These reveal crystalline intermetallic phases and the metallic state of yttrium. Without any optimization of the method, the catalyst has an improved mass activity in comparison to the unmodified catalyst,proving the viability of the method. Initial work based on thermodynamic equilibrium calculations on reduction time show promise in controlling the phase formed by tuning the parameters of time, temperature, and gas composition.
AB - Platinum–rare-earthalloys have proven to be both active and stable under accelerated stability tests in their bulk polycrystalline form. However, a scalable method for the synthesis of a high-surface-area supported catalyst of these alloys has so far not been presented. Herein we discuss the thermodynamics relevant for the reduction conditions of the rare earths to form alloys with platinum. We show how the tolerance for water and oxygen severely limits the synthesis parameters and how under certain conditions the thermal reduction of YCl3 with H2 is possible from 500 °C. From the insight gained, we synthesized a PtxY/C catalyst by modifying a Pt/C catalyst and confirmed alloy formation by both X-ray diffraction and X-ray photoelectron spectroscopy measurements.These reveal crystalline intermetallic phases and the metallic state of yttrium. Without any optimization of the method, the catalyst has an improved mass activity in comparison to the unmodified catalyst,proving the viability of the method. Initial work based on thermodynamic equilibrium calculations on reduction time show promise in controlling the phase formed by tuning the parameters of time, temperature, and gas composition.
KW - Synthesis
KW - Rare earths
KW - Platinum
KW - Alloy
KW - Oxygen reduction reaction
KW - Proton exchange membrane fuel cell
KW - Nanoparticles
U2 - 10.1021/acscatal.7b03972
DO - 10.1021/acscatal.7b03972
M3 - Journal article
VL - 8
SP - 2071
EP - 2080
JO - A C S Catalysis
JF - A C S Catalysis
SN - 2155-5435
ER -