Polyol-Assisted Efficient Hole Transfer and Utilization at the Si-based Photoanode/Electrolyte Interface

The sluggish kinetics of the anodic oxygen evolution reaction significantly restricts the efficiency of silicon (Si)-based photoelectrochemical (PEC) cells. In this study, we employ microfabrication technology to batch-prepare reproducible Si substrates, and develop a facile electrodeposition technique to load high-quality nickel film onto the substrates. Innovatively, we introduce energetically favorable polyols (such as glycerol, propylene glycol, and ethylene glycol) into the electrolyte, resulting in a remarkably low onset potential and a high hole injection efficiency during the PEC oxidation process. Taking glycerol as an example, in-situ impendence spectra provide real-time evidence for the accelerated hole transfer and utilization at the photoanode/electrolyte interface in the presence of glycerol. Mechanistic studies further reveal that glycerol undergoes synergistic oxidation mediated by holes and catalysts. Finally, by intergrating a solar thermoelectric generator into a PEC polyol oxidation cell, the self-powered system demonstrates promising potential for producing valuable products solely by harnessing solar energy.