• 
  Mohamed, R.; Binninger, T.; Kooyman, P.; Hoell, A.; Fabbri, E.; Patru, A.; Heinritz, A.; Schmidt, T.; Levecque, P.: Facile deposition of Pt nanoparticles on Sb-doped SnO₂ support with outstanding active surface area for the oxygen reduction reaction. Catalysis Science & Technology 8 (2018), p. 2672-2685

10.1039/c7cy02591b

Abstract:
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 m2 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.