N-Type Cu2O/α-Fe2O3 Heterojunctions by Electrochemical Deposition: Tuning of Cu2O Thickness for Maximum Photoelectrochemical Performance

Abstract

Abstract Here, we report the enhanced photoelectrochemical performance of surface modified hematite thin films with n-type copper oxide nanostructures (Cu2O/Fe2O3) obtained through simple electrochemical deposition method. The thickness and amount of cuprous oxide layer were varied by simply changing the number of electrodeposition cycles (viz. 5, 10, 25, 50 and 100) in order to understand its thermodynamic and kinetic influence on the photoelectrochemical activity of the resultant nano-heterostructures. Structural and morphological characteristics of the obtained Cu2O/Fe2O3 films have been studied by absorption spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy analysis. Electrochemical investigations such as linear sweep voltammetry, Mott–Schottky analysis, and electrochemical impedance spectroscopy suggested the formation of n-type Cu2O layers over the hematite films with varying charge-carrier densities, ranging from 0.56×1019 to 3.94×1019 cm−3, that varies with the number of cycles of electrochemical deposition. Besides, the thickness of deposited cuprous oxide layer is noted to alter the net electrochemical and photo-electrochemical response of the base material. An interesting, peak event was recorded for a particular thickness of the cuprous oxide layer (obtained after 25 cycles of electrochemical deposition) below and above which the efficiency of catalyst was impaired. The heterojunction obtained thus, followed well known Z-scheme and gave appreciable increment in the photocurrent response.