Fabrication of novel electrospun Al and Cu doped ZnO thin films and evaluation of photoelectrical and sunlight-driven photoelectrochemical properties

In this study, the nanostructured ZnO thin films (TFs) doped with Al (AZO) and Cu (CZO) were developed on FTO substrate via electrospinning method and post calcination for the aim of photoelectmchemical (PEC) water splitting. The microstructure, composition and electro-optical properties of the photoanodes were thoroughly characterized using field emission scanning electron microscopy (FESEM), grazing incidence X-ray diffractometer (GIXRD), Raman, photoluminescence (PL), and UV-Vis spectrometers. Microstructural studies revealed that the nanofibmus mats exchanged to the cross linked ZnO nanoparticles (NPs) in the range of 10-20 nm after calcination at 400 degrees C. Furthermore, the electro-optical studies indicated that Al and Cu could separately be incorporated inside the ZnO wurtzite crystal structure. The absorbance of ZnO TFs was increased, while the band gap of ZnO TFs was decreased from 3.19 eV to 3.12 and 3.04 eV upon doping with Al and Cu, respectively. At a bias potential of 0.4 V vs. Ag/AgCl and under AM 1.5 illumination, the doped AZO and CZO TFs exhibited boosted photocurrent densities which were 16.4 and 16.8 times higher than undoped ZnO, respectively. The CZO assay possess the highest photon conversion efficiency owing to the increased light absorption, homogenous sticked NPs, and faster charge transfer. Moreover, electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M - S) assessments showed the separation of electron-hole pairs under light illumination, and that n-type CZO semiconductor had the highest carrier density. Ultimately, our results open new avenues in using industrial friendly and cost-effective electrospinning fabrication method in order to produce highly efficient PEC water splitting photoelectrodes.