Co-doping Strategy of Hematite for Efficient Water Splitting

In this talk, I report that co-doped hematite photoanodes fabricated with controlled doping conditions can exhibit significantly increased photoelectrochemical (PEC) water splitting activity. The optimized co-doping in hematite not only suppressed the number of metal ions that cause electron hole pair (EHP) recombination at the hematite surface but also generated an internal electric field for easy hole extraction. The co-doped hematite converted the incident photons to EHPs with much reduced recombination and exhibited an excellent photocurrent density of greater than 4 mA/cm² at 1.23 V_RHE. In addition, a tandem device containing a single perovskite solar cell and an optimized co-doped hematite photoanode delivered a high STH efficiency for water splitting, operating without any applied potential. Our co-doping strategy provides a straightforward way of addressing the chronic short-hole diffusion length issue that causes a high electron hole recombination rate, to potentially improve the performance of PEC devices.