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

p-CuSCN/n-Fe2O3 heterojunctions were electrochemically prepared by sequentially depositing alpha-Fe2O3 and CuSCN films on FTO (SnO2:F) substrates. Both alpha-Fe2O3 and CuSCN films and alpha-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 alpha-Fe2O3 films by fixing the SCN/Cu molar ratio in an electrolytic bath to 1:1.5 at 60 degrees C, and at a potential of -0.4 V. The photocurrent measurements showed increased intrinsic surface states or defects at the alpha-Fe2O3/CuSCN interface. The photoelectrochemical performance of the alpha-Fe2O3/CuSCN heterojunction was examined by chronoamperometry and linear sweep voltammetry techniques. The alpha-Fe2O3/CuSCN structure exhibited greater photoelectrochemical activity compared to the alpha-Fe2O3 thin films. The highest photocurrent density was obtained for the alpha-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 alpha-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. (c) 2017 The Electrochemical Society. All rights reserved.