Probing Photocatalytic Oxygen and Hydrogen Evolution Reactions via Single Particle Electrochemistry with Photo-SECM

Particulate photoelectrocatalysts (PEC) have attracted substantial attention due to their potential for renewable fuel generation from sunlight and water. The characterization of reactivity at the active sites of photocatalysts with nanometer-scale spatial resolution is essential for understanding and developing more efficient energy conversion systems. In this study, we present the results of the first single-particle-on-microelectrode oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity measurements assisted by in situ photoelectrochemical scanning electrochemical microscopy (photo-SECM). An individual micrometer-sized Al-doped SrTiO3/Rh2–yCryO3 photocatalyst crystal was immobilized on a carbon fiber microelectrode and probed using a Pt nanoelectrode at various substrate bias conditions to promote OER and HER. Local fluxes of oxygen and hydrogen generated by an individual PEC microcrystal were quantitatively evaluated with COMSOL Multiphysics finite-element simulations.