Nanostructured mixed metal oxides for the electrocatalytic oxidation of water

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The oxygen evolution reaction (OER) on photoanodes is a pivotal step for efficient direct light-driven water splitting. To facilitate this reaction, OER electrocatalysts are indispensable. Low reactivity due to large kinetic overpotentials, corrosive degradation, and the unsustainably precious nature of todays Ru-Ir OER catalysts, however, have remained key barriers to water photoelectrolysis. Also, molecular insights into the reactive intermediates and the nature of the active site are still limited. In the first funding period of this collaborative project within the SPP 1613 we have demonstrated that dealloyed metal-oxide hybrid core-shell nanoparticles based on IrNix alloys and supported on corrosion-resistant conductive oxides constitute highly stable electrocatalysts for the electrocatalytic oxidation of water with unprecedented faradaic and noble metal mass efficiency. For the second funding period we extend our work addressing 4 specific objectives in 4 work packages. Based on DFT calculations of our external collaborating partner, the activity of Ir-oxide OER catalysts can be elevated by incorporating a second metal into the catalyst surface. We will explore the effect of alternative non-precious metals on catalyst activity and stability within the metal-oxide hybrid core-shell approach. Furthermore, a fundamental understanding of the underlying reaction mechanism of the OER of IrMOx and their degradation mechanism will be obtained by using electrochemical kinetic analyses combined with in situ spectroscopic information from XPS, vibrational spectroscopy, environmental SEM and monitoring the rate of potential metal dissolution. In addition, the structure and chemical states of the two solid/solid interfaces relevant for practical PEC cell designs (i.e. the active catalyst/support and support/ PEC-substrate interface) will be investigated and based on the above knowledge and our OER catalyst efficient and stable PEC cells will be fabricated with other projects within SPP 1613.