Hematite (α-Fe2O3) has been extensively investigated as a photoanode for photoelectrochemical (PEC) water splitting. Nevertheless, poor hole transfer efficiency and late turn-on characteristics severely limits the photoelectrochemical performance of hematite electrodes. Numerous methods have been demonstrated to address this limitation, including development of nanostructures, surface passivation, incorporating oxygen evolution reaction catalyst. Yet, the performance of hematite photoanodes can also be limited by the efficiency of initial charge separation and electron transfer, which has been rarely studied. We report a strategy for efficient suppression of electron–hole recombination in hematite photoanodes. Acid treated hematite showed a substantially enhanced photocurrent density compared to untreated samples. Electrochemical impedance spectroscopy studies revealed that the enhanced photocurrent is partly due to improved efficiency of charge separation. Transient absorption spectroscopic studies coupled to electrochemical measurements indicate that, in addition to improved bulk electrochemical properties, acid-treated hematite has significantly decreased surface electron–hole recombination losses owing to a greater yield of the trapped photoelectrons being extracted to the external circuit. The capability of improving photoactivity of hematite electrodes using simple acid treatment method should open up new opportunities for solar energy conversion systems including photoelectrochemical cells and solar cells.

Acid treatment enables suppression of electron-hole recombination in hematite for photoelectrochemical water splitting

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.