Advancing Semiconductor-Based Photoelectrodes for Artificial Photosynthesis

Photoelectrochemical cells (PECs) offer a promising route for converting sunlight into energy-dense and high-value chemicals (e.g. hydrocarbons, hydrogen) via CO2 reduction, water splitting, and nitrate reduction. However, challenges related to the performance and stability of catalysts and semiconductor-based photoelectrodes within complex electrochemical environments necessitate detailed microscopic understanding.<br/>This talk will present the use of advanced correlative characterization techniques, such as Kelvin Probe Force Microscopy (KPFM) and operando Spectroscopic Ellipsometry (SE), to assess photoelectrode surfaces with nanometer precision. For example, using TiO2 thin films deposited by Atomic Layer Deposition (ALD) as a model system, we uncover insights into surface potential evolution and carrier dynamics. A major hurdle in achieving high efficiency is probing the interplay between local morphology and charge carrier dynamics. We demonstrate how time-dependent KPFM can precisely correlate local morphology with optoelectronic properties and degradation mechanisms.<br/>We will also report on the novel catalytic microenvironments to enhance the stability and reaction selectivity of (photo)electrocatalytic materials. We will show examples based on Cu2O, halide perovskites, and ZnTe, and discuss the impact of the semiconductor/electrolyte interface on performance and selectivity.<br/>These advanced techniques can aid detailed understanding of complex catalytic architectures and enable the design of more efficient photoelectrodes, thus advancing sustainable energy production and climate change mitigation.