Dynamically driven rutile-based acidic oxygen evolution electrocatalysts beyond stationary efficiency (DaCapo)

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The project “DaCapo” will study and test a fundamental hypothesis derived from Dynamic Resonance Theory (DRT) as to the feasibility of time-averaged catalytic performance benefits in periodically driven versus stationary operation regimes. The DRT hypothesis will be tested and mechanistically analyzed in terms of catalytic reactivity, stability, and efficiency using the electrocatalytic oxygen evolution reaction (OER) on rutile-based model and nanostructured oxide catalysts under dynamically driven electrode potentials. The key atomistic idea of this approach is to periodically and preferentially populate the surface with reactive intermediates at more cathodic electrode potentials, followed by rapid product formation at more anodic electrode potentials. As a result, at characteristic resonance conditions, where applied parameter variations match intrinsic catalytic time scales, the periodic switching between these two regimes can enhance the overall time-averaged reaction rate and efficiency. We will form a bridge between atomic insights into the dynamics of active site and active surface phases of well-defined catalytic model surfaces and real catalyst materials and multiscale simulations of their dynamic behavior, exemplified by rutile based acidic OER catalyst (IrO2, RuO2, mixed (Ru-Ir-Ti)O2) under the influence of forced oscillatory operation. We will explore the existence, mechanisms, and exploitation of catalytically active dynamic resonant states in the OER under acidic conditions using a three-branched combination of i) ultrahigh vacuum-based and in situ surface science methods (photoemission, vibrational spectroscopies) on single crystal and thin film model electrodes (Hofmann) to elucidate the population of surface species under dynamic electrochemical conditions (DEC); ii) computational studies including density functional theory, dynamic kinetic Monte Carlo (DKMC) and coupling to a numerical model of the electrochemical system (Hess) to predict the influence of DEC on OER activity. Spectroscopic signatures of intermediates on the surface during switching transients will be computed with Ab-initio Molecular Dynamics to assist in the assignment of experimental spectra; iii) electrocatalytic studies on model thin-film and more realistic nanoparticle electrodes employing real-time Differential Electrochemical Mass Spectrometry (DEMS) and operando potentiodynamic X-ray absorption spectroscopy to monitor and correlate product formation rates, surface hole charge, and Faradaic product efficiencies under DEC (Strasser). The experimental data and simulation models obtained in DaCapo will be placed in relation to macroscale modelling of collaborating groups in the SPP2080 with the goal to understand and enable application of dynamic control in OER electrocatalysis through a multiscale understanding.