Enhanced interface charge transfer via n-n WO3/Ti–Fe2O3 heterojunction formation for water splitting.

Inevitable drawbacks on α-Fe 2 O 3 photoanodes, such as poor conductivity, short hole diffusion length, high electron-hole recombination rate, limit their photoelectrochemical (PEC) performance for water oxidation. The construction of heterojunction is an effective approach to improve the PEC performance of photoanodes. Herein, we report the design of the WO 3 /Ti–Fe 2 O 3 heterojunction photoanodes, which are synthesized by two simple hydrothermal method. The optimized WO 3 /Ti–Fe 2 O 3 photoanode shows remarkably improved photocurrent of 2.15 mA/cm2 at 1.23 V versus reversible hydrogen electrode (RHE) without additional cocatalyst, which is higher than that of previous literatures. The improvement benefits from reduced charge transfer resistance in the bulk of Ti–Fe 2 O 3 photoanode and improved charge separation efficiency, which can been further confirmed by electrochemical impedance spectroscopy (EIS), the transient photovoltage (TPV) and the work function (WF) measurement. The present work also provide new opportunities in developing high performance photoanodes for PEC water splitting. WO 3 served as an electron transfer layer can reduce the resistance of interface charge transfer and improve the charge separation efficiency of Ti–Fe 2 O 3. However, charge separation efficiency is closely related to charge injection efficiency, therefore, more holes of Ti–Fe 2 O 3 will transfer to electrolyte to participate in the water oxidation. Image 1 • WO 3 served as an electron transfer layer can reduce the resistance of interface charge transfer. • The introduction of WO 3 can improve the charge separation efficiency of Ti–Fe 2 O 3. • The separation and transfer process of photogenerated charge carriers have been discussed. [ABSTRACT FROM AUTHOR]