In-Situ Monitoring of Nanoparticle Formation during Iridium-Catalysed Oxygen Evolution by Real-Time Small Angle X-Ray Scattering

Maya Singer Hobbs, Emma V. Sackville, Andrew J. Smith, Karen J. Edler, Ulrich Hintermair

Research output: Contribution to journalArticle


Real-time Small Angle X-Ray Scattering (SAXS) has been used to investigate the homogeneity of a series of molecular iridium complexes during water oxidation catalysis in aqueous NaIO4 solution through a continuous flow cell. The results obtained for the unstable [Cp*Ir(OH2)3]2+ precursor forming amorphous IrOx nanoparticles (NPs) in-situ validate and complement previous Dynamic Light Scattering (DLS) studies by providing enhanced sensitivity for small particle sizes and increased temporal resolution under realistic reaction conditions. Correlating particle formation profiles with O2 evolution traces allowed homogeneous catalysis to be clearly distinguished from heterogeneous catalysis. A series of seven pyridine−alkoxide Cp*Ir complexes are shown to be fully homogeneous by SAXS, validating previous studies and confirming their catalysis to be molecular in nature throughout the reaction.

Original languageEnglish
Pages (from-to)5313-5321
Number of pages11
Issue number21
Early online date19 Aug 2019
Publication statusPublished - 7 Nov 2019


  • homogeneous vs. heterogeneous catalysis
  • iridium
  • nanoparticles
  • SAXS
  • water oxidation

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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