Heterojunction of nanostructured α-Fe2O3/CuO for enhancement of photoelectrochemical water splitting

In this research, nanostructured heterojunction of hematite (α-Fe2O3) and porous copper (II) oxide (CuO) composites represented as α-Fe2O3/CuO was prepared and used as photoanode for photoelectrochemical (PEC) water splitting. X-ray diffraction (XRD) and Raman spectroscopy studies confirmed the high purity of α-Fe2O3/CuO heterostructures produced. Enhanced photocurrent density of 0.53 mA/cm2 at 1.0 V versus reversible hydrogen electrode (vs. RHE) was achieved for α-Fe2O3/CuO photoanodes, representing a 19-fold increase compared to the value recorded for α-Fe2O3. The formation of a heterojunction coupled with the porous surface morphology of α-Fe2O3/CuO heterostructure facilitated charge separation of photogenerated electron-hole pairs, enhancing PEC water splitting. The reduced bandgap recorded for α-Fe2O3/CuO resulted in increased absorption of photons in the visible spectrum by the heterostructure, which also influenced the improvement of the photocurrent density. Furthermore, increase in charge carrier density and the reduction of charge transfer resistance at the liquid/solid interface achieved for α-Fe2O3/CuO were additional evidence associated with the improvement in the recorded current density. This research presents the formation of α-Fe2O3/CuO heterojunction structure with porous surface as a viable route to achieving notable improvement in the photo response of α-Fe2O3 photoanodes for PEC water splitting.