(Invited) How Ti Modifies Oxygen Electro-Adsorption and Oxygen Evolution Reaction on IrO2(110) and RuO2(110) Surfaces

Abstract

We present our measurements of the oxygen electro-adsorption and oxygen evolution reaction (OER) on well-defined Ir1-xTixO2(110) and Ru1-xTixO2(110) surfaces grown using molecular-beam epitaxy. The motivation of this contribution is to reveal the role of Ti on the OER electrocatalysis on IrO2 and RuO2. The slow kinetics of the OER is currently the largest source of overpotential (inefficiency) in water-splitting devices. An OER catalyst can reduce this overpotential by stabilizing the OER intermediates via surface electro-adsorption. We study how the Ti addition can impact this capability on IrO2 and RuO2. To understand the effect, we measure the oxygen electro-adsorption and OER on Ir1-xTixO2(110) and Ru1-xTixO2(110) as a function of Ti. Then, using the relationship between the oxygen electro-adsorption, the OER electrocatalysis, and the Ti content, we develop a physical model to explain how Ti affects the OER kinetics from the perspective of the current electrocatalysis theory. We provide possible explanations on why Ti can be sometimes beneficial for the OER and sometimes not. Finally, we will discuss how to design an OER catalyst with distinct cooperative sites to achieve high OER activity in the future.