Electrochemical Fabrication and Characterization of p-CuSCN/n-Fe₂O₃Heterojunction Devices for Hydrogen Production

Abstract

p-CuSCN/n-Fe 2 O 3 heterojunctions were electrochemically prepared by sequentially depositing -Fe 2 O 3 and CuSCN films on FTO (SnO 2 :F) substrates. The -Fe 2 O 3 and CuSCN films and the -Fe 2 O 3 /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 -Fe 2 O 3 films by fixing the SCN/Cu molar ratio in the electrolytic bath to 1:1.5 at 60 C and at a potential of -0.4 V. The photocurrent measurements showed an increase of the intrinsic surface states or defects at the -Fe 2 O 3 /CuSCN interface. The photoelectrochemical performance of the -Fe 2 O 3 /CuSCN heterojunction was examined by chronoamperometry and linear sweep voltammetry techniques. It was found that the -Fe 2 O 3 /CuSCN structure exhibits a higher photoelectrochemical activity when compared to -Fe 2 O 3 thin films. The highest photocurrent density was obtained for -Fe 2 O 3 /CuSCN films in 1 M NaOH electrolyte. This high photoactivity was attributed to the high active surface area and to the external applied bias;, which favors the transfer and the separation of the photogenerated charge carriers in -Fe 2 O 3 /CuSCN heterojunction devices. The flat band potential and the donor density were found to be maximal for the heterojunction. These results suggest a substantial potential to achieve heterojunction thin films in photoelectrochemical water splitting applications.