Iridium oxide (IrO x )-based materials are the most suitable oxygen evolution reaction (OER) catalysts for water electrolysis in acidic media. There is a strong demand from industry for improved performance and reduction of the Ir amount. Here, we report a composite catalyst, IrO x −TiO 2 −Ti (ITOT), with a high concentration of active OH species and mixed valence IrO x on its surface. We have discovered that the obtained ITOT catalyst shows an outstanding OER activity (1.43 V vs RHE at 10 mA cm −2 ) in acidic media. Moreover, no apparent potential increase was observed even after a chronopotentiometry test at 10 mA cm −2 for 100 h and cyclic voltammetry for 700 cycles. We proposed a detailed OER mechanism on the basis of the analysis of the in situ electrochemical X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements as well as density functional theory (DFT) calculations. All together, we have concluded that controllable Ir-valence and the high OH concentration in the catalyst is crucial for the obtained high OER activity.
Ti0.9Zr0.1O2 complex oxide particles exhibit superior catalytic performances for the direct power storage into glycolic acid via electroreduction of oxalic acid due to favorable crystallinity.
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