title: Evolution of iridium-based molecular catalysts during water oxidation with ceric ammonium nitrate.
abstract: Organometallic iridium complexes have been reported as water oxidation catalysts (WOCs) in the presence of ceric ammonium nitrate (CAN). One challenge for all WOCs regardless of the metal used is stability. Here we provide evidence for extensive modification of many Ir-based WOCs even after exposure to only 5 or 15 equiv of Ce(IV) (whereas typically 100-10000 equiv are employed during WOC testing). We also show formation of Ir-rich nanoparticles (likely IrO(x)) even in the first 20 min of reaction, associated with a Ce matrix. A combination of UV-vis and NMR spectroscopy, scanning transmission electron microscopy, and powder X-ray diffraction is used. Even simple IrCl(3) is an excellent catalyst. Our results point to the pitfalls of studying Ir WOCs using CAN.
authors: Department of Chemistry and Biochemistry, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, USA. grotjahn@chemistry.sdsu.edu
authors: Douglas B
authors: DB
authors: Grotjahn
authors: Derek B
authors: DB
authors: Brown
authors: Jessica K
authors: JK
authors: Martin
authors: David C
authors: DC
authors: Marelius
authors: Marie-Caline
authors: MC
authors: Abadjian
authors: Hai N
authors: HN
authors: Tran
authors: Gregory
authors: G
authors: Kalyuzhny
authors: Kenneth S
authors: KS
authors: Vecchio
authors: Zephen G
authors: ZG
authors: Specht
authors: Sara A
authors: SA
authors: Cortes-Llamas
authors: Valentin
authors: V
authors: Miranda-Soto
authors: Christoffel
authors: C
authors: van Niekerk
authors: Curtis E
authors: CE
authors: Moore
authors: Arnold L
authors: AL
authors: Rheingold
mesh_terms: D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D014867:Water; D002563:Cerium; D007495:Iridium; C004653:ceric ammonium nitrate