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. 2020 Aug 9;5(32):20491-20505.
doi: 10.1021/acsomega.0c02646. eCollection 2020 Aug 18.

Development of Cuboidal KNbO3@α-Fe2O3 Hybrid Nanostructures for Improved Photocatalytic and Photoelectrocatalytic Applications

Umar Farooq  1 , Preeti Chaudhary  2 , Pravin P Ingole  2 , Abul Kalam  3 , Tokeer Ahmad  1
Affiliations

Development of Cuboidal KNbO3@α-Fe2O3 Hybrid Nanostructures for Improved Photocatalytic and Photoelectrocatalytic Applications

Umar Farooq et al. ACS Omega. .

Abstract

Monophasic and hybrid nanostructures of KNbO3 and α-Fe2O3 have been prepared using a hydrothermal process for photoelectrocatalytic and photocatalytic applications. Powder X-ray diffraction studies showed the formation of KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3 with average grain sizes of 18.3, 11.5, and 26.1 nm and Brunauer-Emmett-Teller (BET) specific surface areas of 4, 100, and 20 m2/gm, respectively. Under simulated solar irradiation, the as-prepared heterostructure shows enhanced photoelectrocatalytic oxygen evolution reaction (OER) activity compared to pristine KNbO3 and α-Fe2O3. Significant photocatalytic activity of as-synthesized KNbO3/α-Fe2O3 heterostructure photocatalyst was obtained for removal of methylene blue organic dye under visible light, and the percentage activity was found to be 11, 49, and 89% for KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3 photocatalysts, respectively. The dielectric constant was found to be 250.2, 65.2, and 251.5 for KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3 heterostructure, respectively, at 50 °C and 500 kHz frequency.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
XRD patterns of as-prepared KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3.
Figure 2
Figure 2
TEM micrographs of (a) KNbO3, (b) α-Fe2O3, and (c) KNbO3/α-Fe2O3.
Figure 3
Figure 3
FESEM micrographs of (a) KNbO3, (b) α-Fe2O3, and (c) KNbO3/α-Fe2O3; EDX spectra of (d) KNbO3, (e) α-Fe2O3, and (f) KNbO3/α-Fe2O3. The inset in (a) shows the particle size distribution histogram of KNbO3.
Figure 4
Figure 4
Elemental mapping of KNbO3/α-Fe2O3 heterostructure for (a) K, (b) Nb, (c) Fe, and (d) O.
Figure 5
Figure 5
(a) Full-range XPS spectra of KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3 heterostructure, and high-resolution XPS spectra of (b) Nb, (c) K, (d) Fe, and (e) O in pure KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3 heterostructure.
Figure 6
Figure 6
(a) BET surface area isotherm and (b) BJH pore size distribution plots of KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3 heterostructure.
Figure 7
Figure 7
(a) LSV plots in dark (D) and light (L) and (b) Tafel slopes of PEC reaction in the presence of KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3 catalysts.
Figure 8
Figure 8
(a) EIS Nyquist plots and (b) Mott–Schottky (MS) plots for bare core material KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3 heterostructure in the presence of light.
Figure 9
Figure 9
(a) Percentage removal efficiency and (b) kinetics of photocatalytic reaction using bare KNbO3, α-Fe2O3, and KNbO3/α-Fe2O3 heterostructure.
Figure 10
Figure 10
Variation of dielectric constant and dielectric loss with frequency at 50 °C for (a) KNbO3-, (b) α-Fe2O3-, and (c) α-Fe2O3-modified KNbO3 heterostructure.
Figure 11
Figure 11
Variation of dielectric constant and dielectric loss with temperature at 500 kHz frequency for (a) KNbO3-, (b) α-Fe2O3-, and (c) α-Fe2O3-modified KNbO3 heterostructure.
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