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Article

Mono-Doped and Co-Doped Nanostructured Hematite for Improved Photoelectrochemical Water Splitting

Department of Physics, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
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Author to whom correspondence should be addressed.
Academic Editor: Alexandru Mihai Grumezescu
Nanomaterials 2022, 12(3), 366; https://doi.org/10.3390/nano12030366
Received: 16 November 2021 / Revised: 15 December 2021 / Accepted: 22 December 2021 / Published: 24 January 2022
(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)
In this study, zinc-doped (α-Fe2O3:Zn), silver-doped (α-Fe2O3:Ag) and zinc/silver co-doped hematite (α-Fe2O3: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 mAcm2 at 1.23 V vs. reversible hydrogen electrode (RHE) was recorded for α-Fe2O3:Zn/Ag. The α-Fe2O3:Ag, α-Fe2O3:Zn and pristine hematite samples produced photocurrent densities of 0.270, 0.160, and 0.033 mAcm2, respectively. Mott–Schottky analysis showed that α-Fe2O3:Zn/Ag had the highest free carrier density of 8.75 × 1020 cm3, while pristine α-Fe2O3, α-Fe2O3:Zn, α-Fe2O3:Ag had carrier densities of 1.57 × 1019, 5.63 × 1020, and 6.91 × 1020 cm3, respectively. Electrochemical impedance spectra revealed a low impedance for α-Fe2O3: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. View Full-Text
Keywords: hematite nanoparticles; doping; chemical spray pyrolysis; photocurrent; water-splitting; transient absorption spectroscopy hematite nanoparticles; doping; chemical spray pyrolysis; photocurrent; water-splitting; transient absorption spectroscopy
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MDPI and ACS Style

Nyarige, J.S.; Paradzah, A.T.; Krüger, T.P.J.; Diale, M. Mono-Doped and Co-Doped Nanostructured Hematite for Improved Photoelectrochemical Water Splitting. Nanomaterials 2022, 12, 366. https://doi.org/10.3390/nano12030366

AMA Style

Nyarige JS, Paradzah AT, Krüger TPJ, Diale M. Mono-Doped and Co-Doped Nanostructured Hematite for Improved Photoelectrochemical Water Splitting. Nanomaterials. 2022; 12(3):366. https://doi.org/10.3390/nano12030366

Chicago/Turabian Style

Nyarige, Justine Sageka, Alexander T. Paradzah, Tjaart P. J. Krüger, and Mmantsae Diale. 2022. "Mono-Doped and Co-Doped Nanostructured Hematite for Improved Photoelectrochemical Water Splitting" Nanomaterials 12, no. 3: 366. https://doi.org/10.3390/nano12030366

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