UC San Diego

The advancement of heterogeneous catalysis and electrocatalysis is essential for developing new energy conversion and storage technologies. Traditionally, heterogeneous catalysis design has focused on engineering the interaction of surface sites in a steady-state model to achieve a "just-right" binding strength to the adsorbate. Recent models predict that dynamically controlling the binding energy of catalytic sites to reaction intermediates can result in per-site activities that outperform previous steady-state catalysis models. Ferroelectric nanomaterials offer a unique opportunity for dynamic catalysis as they can present two distinct chemical surfaces depending on their polarization direction adding an additional dimension to control the interaction of adsorbates with the catalytic surface.This thesis is an effort to design, model and investigate ferroelectric perovskites and their implications in the new paradigm of dynamic electrocatalysis. To achieve this a combination of ab-initio DFT calculations, synchrotron-based spectroscopy and electrochemical measurement were employed to investigate the role of ferroelectric polarization in perovskite thin films grown by molecular beam epitaxy. First the role of polarization switching on the surface structure of bare BaTiO3 ferroelectric thin films and their implications toward hydrogen evolution reaction as a model reaction has been stablished. Next, a combination of computational spectroscopy based on many-body electron excitations and synchrotron scanning tunneling microscopy was used to investigate the role of polarization switching on X-Ray absorption of BaTiO3 and its O2 adsorption activity. After stablishing the role of ferroelectric switching on the surface chemistry an electronic structure of bare thin films, a complex heterostructures consisting of a ferroelectric BaTiO3 layer and an atomically thin SrRuO3 layer acting as catalytic skin was constructed. It was shown that this model exhibits ~3 times higher catalytic activity for hydrogen evolution reaction in dynamic mode compared with steady-state conditions. Coupling dynamics with intrinsic properties of exotic materials such as ferroelectrics to control the interaction of intermediates over a single catalytic surface as demonstrated here can offer a wide array of enhancements in catalysis beyond traditional steady-state models.