Dan Wang,Ying Chen,Yang Zhang,Xintong Zhang,Norihiro Suzuki,Chiaki Terashima
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.
Weiwei Xu,Wei Tian,Linxing Meng,Fengren Cao,Liang Li
Due to its suitable band energy level and small band gap, CdIn 2 S 4 is a promising photoanode for photoelectrochemical (PEC) water splitting. Nevertheless, the serious charge recombination at the back contact and photoelectrode/electrolyte interface severely hinders its PEC activity. Herein, a facile magnetron ion-sputtering strategy is adopted to fabricate TiO 2 underlayer and NiO overlayer to modify both sides of CdIn 2 S 4 photoanode. The TiO 2 underlayer serves as an electron transport layer to promote electrons transfer from CdIn 2 S 4 to fluorine-doped tin oxide substrate and hinder holes' transportation, thus suppressing the charge recombination at the back contact. NiO, as a p-type semiconductor, forms a p-n heterojunction with CdIn 2 S 4 , inducing a built-in electric field to facilitate charge transport. Meanwhile, NiO overlayer acts as a co-catalyst to enhance surface reaction kinetics, and thereby improves the carrier injection efficiency at photoelectrode/electrolyte interface. As a result, the optimum TiO 2 /CdIn 2 S 4 /NiO photoanode exhibits photocurrent as high as 0.6 mA cm −2 at 1.23 V versus reversible hydrogen electrode, which is about 2.3 times that of bare CdIn 2 S 4 . This work provides an effective strategy to manipulate the charge carrier dynamics to improve the PEC activity of photoanode.
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