Abstract
In this study, zinc-doped (-FeO:Zn), silver-doped (-FeO:Ag) and zinc/silver co-doped hematite (-FeO:Zn/Ag) nanostructures were synthesized by spray pyrolysis. The synthesized nanostructures were used as photoanodes in the photoelectrochemical (PEC) cell for water-splitting. A significant improvement in photocurrent density of 0.470 mAcm at 1.23 V vs. reversible hydrogen electrode (RHE) was recorded for -FeO:Zn/Ag. The -FeO:Ag, -FeO:Zn and pristine hematite samples produced photocurrent densities of 0.270, 0.160, and 0.033 mAcm, respectively. Mott–Schottky analysis showed that -FeO:Zn/Ag had the highest free carrier density of 8.75 × 10 cm, while pristine -FeO, -FeO:Zn, -FeO:Ag had carrier densities of 1.57 × 10, 5.63 × 10, and 6.91 × 10 cm, respectively. Electrochemical impedance spectra revealed a low impedance for -FeO:Zn/Ag. X-ray diffraction confirmed the rhombohedral corundum structure of hematite. Scanning electron microscopy micrographs, on the other hand, showed uniformly distributed grains with an average size of <30 nm. The films were absorbing in the visible region with an absorption onset ranging from 652 to 590 nm, corresponding to a bandgap range of 1.9 to 2.1 eV. Global analysis of ultrafast transient absorption spectroscopy data revealed four decay lifetimes, with a reduction in the electron-hole recombination rate of the doped samples on a timescale of tens of picoseconds.
Highlights
Solar energy is one of the alternative solutions to the existing gap of energy demand if proper utilization is done
Evolution-associated difference spectra (EADS) and corresponding decay lifetimes were obtained
X-ray diffraction studies confirmed hematite with the corundum structure with an R3̄C space group with a = b = 5.075 Å and c = 13.748 Å lattice parameters
Summary
Solar energy is one of the alternative solutions to the existing gap of energy demand if proper utilization is done. One of the effective and clean approaches for the production of clean energy is solar-driven water-splitting, where hydrogen (H2 ) and oxygen (O2 ) gases are released [2]. During this process, sunlight is absorbed using a suitable semiconductor producing electron-hole (e− h+ ) pairs. To study the electron-hole lifetimes and exciton dynamics of hematite nanostructured thin films, several transient absorption spectroscopy (TAS) studies have been conducted [11,15,16,17]. Femtosecond and picosecond timescales obtained by ultrafast transient absorption spectroscopy measurements of doped hematite reported reduction in the electron-hole recombination. 0.470 mAcm−2 for α-Fe2 O3 :Zn/Ag at 1.23 V vs. RHE
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
