Electrochemical Fabrication and Characterization of p-CuSCN/n-Fe2O3 Heterojunction Devices for Hydrogen Production

Abstract

p-CuSCN/n-Fe2O3 heterojunctions were electrochemically prepared by sequentially depositing α-Fe2O3 and CuSCN films on FTO (SnO2:F) substrates. Both α-Fe2O3 and CuSCN films and α-Fe2O3/CuSCN heterojunctions were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Pure crystalline CuSCN films were electrochemically deposited on α-Fe2O3 films by fixing the SCN/Cu molar ratio in an electrolytic bath to 1:1.5 at 60°C, and at a potential of −0.4 V. The photocurrent measurements showed increased intrinsic surface states or defects at the α-Fe2O3/CuSCN interface. The photoelectrochemical performance of the α-Fe2O3/CuSCN heterojunction was examined by chronoamperometry and linear sweep voltammetry techniques. The α-Fe2O3/CuSCN structure exhibited greater photoelectrochemical activity compared to the α-Fe2O3 thin films. The highest photocurrent density was obtained for the α-Fe2O3/CuSCN films in 1 M NaOH electrolyte. This strong photoactivity was attributed to both the large active surface area and the external applied bias, which favored the transfer and separation of the photogenerated charge carriers in the α-Fe2O3/CuSCN heterojunction devices. The flatband potential and donor density were maximal for the heterojunction. These results suggest a substantial potential to achieve heterojunction thin films in photoelectrochemical water splitting applications.