Boosting photoelectrochemical performance of hematite photoanode with TiO2 underlayer by extremely rapid high temperature annealing

Extremely rapid high temperature annealing (ER-HTA) was used to boost the photoelectrochemical (PEC) performance of hematite thin film deposited on a TiO 2 nanosheet-modified SnO 2 :F substrate (FTO-TN-HM). The PEC performance of FTO-TN-HM photoanodes were strongly enhanced with increasing ER-HTA temperatures from 700 to 820   °C with a holding time as short as 30   s. The photocurrent density of FTO-TN-HM photoanode treated by ER-HTA at 800   °C was 0.49   mA   cm -2 and interfacial hole transfer efficiency of 32% was achieved at 1.23   V vs. RHE, which were 18.8 and 16 times as great as FTO-TN-HM photoanodes annealed at 500   °C for 30   min, respectively. The effect of ER-HTA on the PEC performance of FTO-TN-HM photoanodes were studied comparatively, which suggested that the improved crystallinity, decreased recombination through surface states, and enhanced interfacial Ti 4+ diffusion all contributed to their advanced PEC performance. Our studies confirm that the ER-HTA treatment is an effective method to improve the PEC properties of hematite photoanodes with TiO 2 underlayer and might be applicable for other semiconducting photoelectrodes to get better PEC performance.