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

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 TiO2 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 TiO2-protected silicon. The obtained composite exhibited greatly improved photoelectrochemical (PEC) performance, where continuous hydrogen production with similar to 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 TiO2 layer avoided the self-reduction of TiO2, 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.

Automated summary

In this study, Ti-doped hematite with ordered mesoporous structure was synthesized and coated on TiO2-protected silicon, significantly enhancing the photoelectrochemical performance. Ti doping led to a more uniform dispersion of photoelectrons on the surface, while the low electronic concentration in the TiO2 layer prolonged the device lifetime. This research provides an effective protection mechanism for composite photoelectrodes, offering a promising strategy for protecting the photocathode through surface decoration with carefully tailored catalysts.