Enhancing the Long-Term Photoelectrochemical Performance of TiO₂/Si Photocathodes by Coating of Ti-Doped Mesoporous Hematite

Abstract

Hematite has been demonstrated as a promising surface cocatalyst for photoelectrochemical cathodes in a strong alkaline electrolyte. However, the reliability of hematite-sensitized photocathodes is still inadequate even with an extra TiO 2 passivation layer. Titanium (Ti) doping is shown to significantly enhance the conductivity of hematite. Herein, ordered mesoporous Ti-doped hematite was presynthesized and coated on the surface of TiO 2protected silicon. The obtained composite exhibited greatly improved photoelectrochemical (PEC) performance, where continuous hydrogen production with ∼12 mA cm −2 at 0 V versus a reversible hydrogen electrode for over a week (168 h) with only 5% photocurrent decay in 1.0 M KOH solution was achieved, more than an order of magnitude enhancement in lifetime relative to the pristine hematite. The surface potential investigation suggested a more uniform dispersion of photoelectrons on the surface through Ti doping in hematite particles. The low electronic concentration in the TiO 2 layer avoided the self-reduction of TiO 2 , prolonging the lifetime of the device. This study develops an effective protection mechanism for composite photoelectrodes, providing a promising strategy to protect the photocathode via surface decoration of meticulously tailored catalysts.

Heteroepitaxial Growth of GaP Photocathode by Hydride Vapor Phase Epitaxy for Water Splitting and CO2 Reduction

“…Highly ordered mesoporous WP was prepared with a previously reported process [37]. WP was spin-coated on the TiO 2 /p-GaP, followed by annealing and fixing by a necking strategy, which is described elsewhere [61]. The WP spin-coating was performed using a suspension (10 mg/mL) of WP in a 1:1 mixture of ethanol and methanol, with three 150 µL drops being separately applied to each sample at 3000 rpm.…”

Robust SrTiO3 Passivation of Silicon Photocathode by Reduced Graphene Oxide for Solar Water Splitting

“…Numerous materials have been developed as a passivation layer to protect p-Si photocathodes from oxidation and (photo)­corrosion under the PEC operational conditions. ,,− Among them, transition metal oxides (e.g., TiO 2 , Al 2 O 3 , Ta 2 O 5 , etc.) have attracted great interest due to their optical transparency and robust chemical stability .…”