(436b) Core-Shell Photoelectrochemical Electrodes for Water Splitting

Photoelectrochemical (PEC) processes offer one of most promising ways to convert solar energy into fuels (e.g. H₂, and CH₃OH), especially H₂. In order to synthesize high efficient and stable PEC water splitting electrodes, one must optimize the light absorption, charge separation, and charge transfer processes of the electrode simultaneously. Core-shell nanostructures with transparent conductive cores and semiconductor shells show great promise for optimizing PEC performance of photoactive materials, such as TiO₂.  However, limited research has been performed in this field. 

We will present the result of using transparent conductive network consisting of low cost, solution-processed antimony doped tin oxide nanoparticles (nanoATO) and tin doped indium oxide nanoparticles (nanoITO) for enabling core-shell TiO₂ PEC electrodes. In detail, we will present the synthesis of TiO₂ PEC electrodes by coating solution-processed nanoATO on FTO glass with TiO₂ through atomic layer deposition (ALD). The conductive, porous nanoATO film-supported TiO₂ electrodes, yielded a highest photocurrent density of 0.58 mA/cm² under AM 1.5G simulated sunlight of 100 mW/cm². This is approximately 3× the maximum photocurrent density of planar TiO₂ PEC electrodes on FTO glass. Transient photocurrent measurements showed that nanoATO films reduce charge recombination by accelerating transport of photoelectrons through the less defined conductive porous nanoATO network. Further, we will show that the effect of interfacial reaction during the TiO₂ (TiCl₄/H₂O) ALD on transparent nanoATO and nanoITO on their PEC performance. The scalable solution-processed porous transparent nanoATO and nanoITO films are promising as a framework to replace other conductive scaffolds (Si nanowire forest, CNTs, and TiSi₂ nanonets) for PEC electrodes.  The results are not only valuable for PEC, but also informative for the related DSSC research.