Cu2+ and Y3+ co-doped effect on morphology, structural, optical and photoelectrochemical properties of Fe2O3 photoanode

Abstract Cu and Y co-doped hematite (α-Fe2O3) nanostructured photoanodes with excellent optical properties were synthesized for photoelectrochemical water splitting (PWS) applications. The effects of the dopants on the crystal structure, morphology, and optical and chemical properties of the Fe2O3 photoanodes were investigated. Structural and chemical analyses confirmed the substitution of Cu and Y ions into the Fe2O3 nanostructures. With an increase in the Y dopant concentration, the bandgap of the photoanodes decreased from ~1.85 to ~1.35 eV. The dopants acted as charge contributors and enhanced the electron-hole densities of the photoanodes. The co-doped Fe2O3 photoanodes showed higher photocurrents and hence higher incident light absorption capacities than did the undoped and Cu-doped samples. The α-Fe2O3 photoelectrode co-doped with 0.3 mol% Y and 0.1% Cu showed the highest photocurrent density of ~0.44 mA/cm2, which is ~41 times of that of the undoped Fe2O3 (0.01 mA/cm2) photoanode and ~ 7 times of that of the 0.1 mol% Cu-doped α-Fe2O3 photoanode. Furthermore, the Cu-doped photoanode showed a very low photocurrent density of 0.06 mA/cm2, which is only ~6 times of that of the undoped α-Fe2O3 photoanode. The high photocurrents of the co-doped photoanodes can be attributed to their high electron donor densities and low electron-hole recombination rates.