(Invited) Solar-Driven Chemical Conversion Using Silicon Photoelectrochemical Cells

Abstract

Solar-driven chemical conversion using photoelectrochemical (PEC) cells has attracted intense interests to produce value-added chemical fuels and feedstock using solar energy. In particular, silicon is attractive for a photoelectrode since it’s earth-abundant and low cost, and has small bandgap to absorb most of solar spectrum. However, silicon suffers from slow kinetics for PEC reactions such as water splitting and CO2 reduction and also from severe corrosion during the operation. In this talk, I’ll present our strategies to develop a high performance and stable silicon-based PEC cells. Firstly, I’ll discuss the light-matter-chemical interaction occurring on a photoelectrode’s surface and demonstrate that PEC reactions are coupled with light abosorption and electrocatalysis bound on the surface of a photoelectrode. Based on these understanding, I’ll present our approaches to maximize light absorption and electrocatalysis in PEC cells (1) by using locally defined 3-dimensional cocatalysts and (2) by using a transparent cocatalysts on Si photoelectrodes. Influences of surface area and coverage of cocatalysts as well as charge transport properties of Si photoelectrodes will be presented using water oxidation reaction as a model chemical reaction. I’ll also show that these approaches can be applicable to CO2 reduction reactions.