TY  - JOUR
AU  - Pappert, Kevin
AU  - Loza, Kateryna
AU  - Shviro, Meital
AU  - Hagemann, Ulrich
AU  - Heggen, Marc
AU  - Dunin-Borkowski, Rafal
AU  - Schierholz, Roland
AU  - Maeda, Takuya
AU  - Kaneko, Kenji
AU  - Epple, Matthias
TI  - Nanoscopic Porous Iridium/Iridium Dioxide Superstructures (15 nm): Synthesis and Thermal Conversion by In Situ Transmission Electron Microscopy
JO  - Chemistry - a European journal
VL  - 25
IS  - 47
SN  - 1521-3765
CY  - Weinheim
PB  - Wiley-VCH
M1  - FZJ-2019-06514
SP  - 11048 - 11057
PY  - 2019
AB  - 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.
LB  - PUB:(DE-HGF)16
C6  - pmid:31140211
UR  - <Go to ISI:>//WOS:000479852000001
DO  - DOI:10.1002/chem.201901623
UR  - https://juser.fz-juelich.de/record/867916
ER  -