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. 2022 Aug 16;4(18):3996-4008.
doi: 10.1039/d2na00361a. eCollection 2022 Sep 13.

The enhanced photocatalytic performance and first-principles computational insights of Ba doping-dependent TiO2 quantum dots

Muhammad Ikram  1 , Muhammad Ahsan Ul Haq  2 , Ali Haider  3 , Junaid Haider  4 , Anwar Ul-Hamid  5 , Iram Shahzadi  6 , Muhammad Ahsaan Bari  1 , Salamat Ali  2 , Souraya Goumri-Said  7 , Mohammed Benali Kanoun  8
Affiliations

The enhanced photocatalytic performance and first-principles computational insights of Ba doping-dependent TiO2 quantum dots

Muhammad Ikram et al. Nanoscale Adv. .

Abstract

Degradation in the presence of visible light is essential for successfully removing dyes from industrial wastewater, which is pivotal for environmental and ecological safety. In recent years, photocatalysis has emerged as a prominent technology for wastewater treatment. This study aimed to improve the photocatalytic efficiency of synthesized TiO2 quantum dots (QDs) under visible light by barium (Ba) doping. For this, different weight ratios (2% and 4%) of Ba-doped TiO2 QDs were synthesized under ambient conditions via a simple and modified chemical co-precipitation approach. The QD crystal structure, functional groups, optical features, charge-carrier recombination, morphological properties, interlayer spacing, and presence of dopants were analyzed. The results showed that for 4% Ba-doped TiO2, the effective photocatalytic activity in the degradation process of methylene blue (MB) dye was 99.5% in an alkaline medium. Density functional theory analysis further corroborated that the band gap energy was reduced when Ba was doped into the TiO2 lattice, implying a considerable redshift of the absorption edge due to in-gap states near the valence band.

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Conflict of interest statement

There are no conflicts to declare.

Figures

Fig. 1
Fig. 1. Schematic diagram of the synthesized Ba-doped TiO2 QDs.
Fig. 2
Fig. 2. Schematic photocatalytic mechanism of the Ba-doped TiO2 QDs.
Fig. 3
Fig. 3. (a) X-ray diffraction patterns, (b) FTIR spectra and (c–e) SAED patterns of pure and Ba (2%, 4%)-doped TiO2 QDs.
Fig. 4
Fig. 4. (a) Absorbance spectra, (b) Eg by Tauc plot, (c) photoluminescence spectra and (d) Raman spectra of the TiO2 and Ba (2%, 4%)-doped TiO2 QDs.
Fig. 5
Fig. 5. (a–c) FESEM images and (d–f) EDS analysis of pure and Ba (2%, 4%)-doped TiO2.
Fig. 6
Fig. 6. (a–c) TEM images of pure and Ba (2%, 4%)-doped TiO2; (d–f) interlayer d-spacing HRTEM images of undoped and Ba-doped TiO2.
Fig. 7
Fig. 7. Photocatalytic degradation of TiO2 and Ba (2% 4%)-doped TiO2 in (a) neutral, (b) acidic and (c) basic media and (d) the photocatalytic degradation of MB by 4% Ba-doped TiO2.
Fig. 8
Fig. 8. N2 adsorption–desorption isotherms.
Fig. 9
Fig. 9. Computational model (a 2 × 2 × 2 supercell) for the anatase (a) TiO2 and (b) Ba-doped TiO2.
Fig. 10
Fig. 10. Calculated total of (a) pure, (b) 3.125% Ba- and (c) 6.25% Ba-doped TiO2 using the DFT-1/2 method. The Fermi level is represented by the red vertical dashed line.
Fig. 11
Fig. 11. PDOS of (a) pristine TiO2 and (b) 3.125% Ba-doped TiO2 and (c) the optical absorption spectra.
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