Enhanced photoelectrochemical performance of ZnO/α-Fe2O3 heterojunction photoelectrode fabricated by facile hydrothermal and spin-coating method

The present study reports the successful fabrication of ZnO/α-Fe2O3 heterojunctions by facile and simple hydrothermal and spin-coating methods. The effect of spin-coating different FeCl3 precursor layers on the photoelectrochemical performance has been investigated. Additionally, the procedure of spin-coating FeCl3 precursors was simulated by fluent software. It is noteworthy that ZnO/α-Fe2O3 heterojunctions increase the absorption of visible light, promote the separation and transfer of photogenerated charge carriers, reduce the interfacial resistance between the photoelectrode and electrolyte, and provide a larger electrochemically active contact area in contrast to pure ZnO nanorods. The highest photocurrent density and the highest IPCE (incident photon-to-current efficiency) reach 1.82 mA cm−2 and 40 % respectively when spin-coating three layers. Moreover, the mechanism of enhanced PEC performance was further discussed via EIS (electrochemical impedance spectroscopy), Mott-Schottky curves, Energy band structure diagram, and the electrochemical active surface area (ECSA) test.