Journal
CATALYSIS SCIENCE & TECHNOLOGY
Volume 8, Issue 10, Pages 2672-2685Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c7cy02591b
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Funding
- South African Department of Science and Technology
- Competence Center for Energy and Mobility (CCEM) Switzerland
- Umicore AG & Co. KG within the project DuraCat
- National Research Foundation of South Africa [94878]
- Innovation Postdoctoral Fellowship
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Understanding the influence of the support on the electrocatalytic behaviour of platinum is key to the development of novel Pt/oxide catalysts for the oxygen reduction reaction (ORR). For studies to isolate these effects, highly dispersed supported Pt nanoparticles with well-controlled particle sizes are required. In this study, we demonstrate a novel preparation process for Pt/oxide catalysts, with small Pt nanoparticles (2.5-3.5 nm), supported on a commercial Sb-SnO2 (ATO) nanopowder, with a very high utilization of the Ptprecursor. The organometallic chemical deposition method produces catalyst nanoparticles with a homogeneous distribution over the surface of the support even at high Pt metal loadings. Additionally, by using a mild hydrogen reduction treatment of the oxide support prior to Pt deposition, significantly smaller Pt nanoparticles were obtained with an outstanding mass-specific electrochemically active surface area exceeding 100 m(2) g(-1). Furthermore, by varying the Pt metal loading, several fundamental electrocatalytic effects that strongly influence the Pt/ATO system were distinguished. Good electrochemical stability during high-potential cycling was observed and was attributed to potential-dependent in situ conductivity switching of the ATO support. In turn, ORR activities of the Pt/ATO catalysts were found to be influenced by a combination of Pt particle size effects, ATO support in situ conductivity limitations at PEFC operation potentials, and electrocatalytic metal-support interactions. Therefore, in addition to demonstrating a powerful method for the preparation of exceptionally high surface area Pt/oxide catalysts, the present study contributes to the detailed understanding of the interplay between various phenomena that influence the electrocatalytic activity and stability of Pt/oxide systems for the ORR. Furthermore, the novel preparation approach for Pt/metal oxide catalysts could be of major interest for catalyst preparation in other fields of electrocatalysis and heterogeneous catalysis.
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