The effect of fast and slow surface states on photoelectrochemical performance of hematite photoanodes fabricated by electrodeposition and hydrothermal methods

The hematite films prepared by electrodeposition (ED) and hydrothermal (HT) methods have similar nanorods morphology and the same length. However, the hematite prepared by HT method has higher photocurrent density and negative shift of onset potential. The samples are systematically characterized by scanning electron microscopy, UV–Vis spectra, X-ray diffractometry and photoelectrochemical measurements. The results reveal that the enhanced photoelectrochemical (PEC) performance of HT hematite is attributed to the superior surface charge injection efficiency, which is caused by a slower surface recombination rate rather than a more catalytically active hematite surface. And the slower surface recombination rate can be attributed to the absence of the slow surface states C_SS2. This work provides an in-depth understanding of the reasons for the different PEC performance of hematite photoanodes fabricated by ED and HT methods, which is of certain significance in guiding the modification of hematite photoanodes prepared by the two typical routes in PEC water splitting system.