Spray pyrolytically deposited Fe-doped Cu2O thin films for solar hydrogen generation: Experiments & first-principles analysis

We present here a combined study on photocatalysis by Fe-doped Cu2O thin films using first-principles density functional theory (DFT) based calculations and experiments. The results of DFT calculations show that the top of the valence band and bottom of the conduction band of undoped Cu2O lies at the Γ point of Brillouin zone, suggesting that pure Cu2O a direct band gap material. However, there is an appearance of a sharp peak at the fermi energy level in the total density of states of Fe-doped Cu2O that essentially comes from Fe 3d states, keeping it still a direct band gap material. To validate the theoretical results, experiments were carried out by preparing thin films of Cu2O doped with 0, 1.0, 2.0, 3.0 & 5.0 atom % Fe via spray pyrolysis method and characterized with X-Ray Diffractometry (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM), UV-Vis Spectroscopy and Photoelectrochemical measurements. The results exhibited that 2 atom % Fe-doped Cu2O sample produces significant photocurrent of 1.86 mAcm−2 at 0.8 V/SCE as compared to undoped Cu2O samples of 0.62 mAcm2 at 0.8 V/SCE with an experimental band-gap value of 2.21 and 2.50 eV respectively. The observed change in the experimental band gap and that estimated by first-principles calculations compare well, thus suggesting that such calculations have the potential to be used in screening various dopants before performing the experiments thereby saving precious chemicals, time and energy.