Effect of plasmonic Ag nanowires on the photocatalytic activity of Cu doped Fe2O3 nanostructures photoanodes for superior photoelectrochemical water splitting applications

Abstract

The Present study focuses on the synthesis and analysis of Cu doped hematite (α-Fe2O3) nanostructures for effectively enhancing the optical properties as well as their implementation as photoelectrodes for energy-harvesting applications. In addition to this, the influence of noble metal plasmonic layer of Ag nanowires as a bottom layer for undoped and doped Fe2O3 photoanodes has been investigated. Herein, we studied the influence of dopant on morphology, structural, and optical properties of Fe2O3. X-ray diffraction technique and X-ray photoelectron spectroscopy analysis were confirmed Cu ion substitution into host Fe2O3 nanostructures. The optical band gap decreases from ~ 1.95eV to ~ 1.38eV with increasing of Cu dopant concentration. Impedance analysis reveals that the Cu dopant works as an electron donor and improves the Fe2O3 charge carrier density. The photoelectrochemical water splitting studies reveals that the photoanodes without plasmonic layer was shown improved photocurrents compare to the undoped sample, thus improving the absorption of the incident light. Significantly, the optimized 0.2mol% Cu-doped α-Fe2O3 photoelectrodes without Ag layer reached the maximum photocurrent density of ~0.31mA/cm2, ~ 28-fold that of pure Fe2O3 (0.011mA/cm2). Further, the same photoanode with plasmonic Ag nanowires showed a significantly improved photocurrent density of 1.48mA/cm2, which is ~ 135-fold that of pure Fe2O3 and ~ 5-folds that of 0.2mol% Cu doped α-Fe2O3 photoelectrodes without plasmonic nanowire layer. The superior photocurrent is ascribed to the enhanced electron donor density and reduced charge recombination rate, as an outcome of optimized Cu doping and Ag nanowires.