%0 Journal Article
%A Pappert, Kevin
%A Loza, Kateryna
%A Shviro, Meital
%A Hagemann, Ulrich
%A Heggen, Marc
%A Dunin-Borkowski, Rafal
%A Schierholz, Roland
%A Maeda, Takuya
%A Kaneko, Kenji
%A Epple, Matthias
%T Nanoscopic Porous Iridium/Iridium Dioxide Superstructures (15 nm): Synthesis and Thermal Conversion by In Situ Transmission Electron Microscopy
%J Chemistry - a European journal
%V 25
%N 47
%@ 1521-3765
%C Weinheim
%I Wiley-VCH
%M FZJ-2019-06514
%P 11048 - 11057
%D 2019
%X Porous particle superstructures of about 15 nm diameter,consisting of ultrasmall nanoparticles of iridium andiridium dioxide, are prepared through the reduction ofsodium hexachloridoiridate(+IV) with sodium citrate/sodiumborohydride in water. The water-dispersible porous particlescontain about 20 wt% poly(N-vinylpyrrolidone) (PVP), whichwas added for colloidal stabilization. High-resolution transmissionelectron microscopy confirms the presence of bothiridium and iridium dioxide primary particles (1–2 nm) ineach porous superstructure. The internal porosity(58 vol%) is demonstrated by electron tomography. In situtransmission electron microscopy up to 1000 8C underoxygen, nitrogen, argon/hydrogen (all at 1 bar), and vacuumshows that the porous particles undergo sintering and subsequentcompaction upon heating, a process that starts ataround 250 8C and is completed at around 8008C. Finally,well-crystalline iridium dioxide is obtained under all four environments.The catalytic activity of the as-prepared poroussuperstructures in electrochemical water splitting (oxygenevolution reaction; OER) is reduced considerably upon heatingowing to sintering of the pores and loss of internal surfacearea.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:31140211
%U <Go to ISI:>//WOS:000479852000001
%R 10.1002/chem.201901623
%U https://juser.fz-juelich.de/record/867916