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. 2023 Feb 21;13(5):794.
doi: 10.3390/nano13050794.

Oxygen Vacancy Mediated Band-Gap Engineering via B-Doping for Enhancing Z-Scheme A-TiO2/R-TiO2 Heterojunction Photocatalytic Performance

Changqing Liu  1 , Chenggang Xu  1 , Wanting Wang  1 , Long Chen  1 , Xu Li  1 , Yuanting Wu  1
Affiliations

Oxygen Vacancy Mediated Band-Gap Engineering via B-Doping for Enhancing Z-Scheme A-TiO2/R-TiO2 Heterojunction Photocatalytic Performance

Changqing Liu et al. Nanomaterials (Basel). .

Abstract

Fabrication of Z-scheme heterojunction photocatalysts is an ideal strategy for solving environmental problems by providing inexhaustible solar energy. A direct Z-scheme anatase TiO2/rutile TiO2 heterojunction photocatalyst was prepared using a facile B-doping strategy. The band structure and oxygen-vacancy content can be successfully tailored by controlling the amount of B-dopant. The photocatalytic performance was enhanced via the Z-scheme transfer path formed between the B doped anatase-TiO2 and rutile-TiO2, optimized band structure with markedly positively shifted band potentials, and the synergistically-mediated oxygen vacancy contents. Moreover, the optimization study indicated that 10% B-doping with the R-TiO2 to A-TiO2 weight ratio of 0.04 could achieve the highest photocatalytic performance. This work may provide an effective approach to synthesize nonmetal-doped semiconductor photocatalysts with tunable-energy structures and promote the efficiency of charge separation.

Keywords: Z-scheme heterojunction; anatase TiO2/rutile TiO2; band structure; oxygen vacancy.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) XRD patterns of the prepared catalysts, and (b) locally-magnified diagrams of the (101) peak of A-TiO2 and the (110) peak of R-TiO2.
Figure 2
Figure 2
SEM images of all the prepared catalysts: (a) pure-TiO2, (b) 4% B-TiO2, (c) 8% B-TiO2, (d) 10% B-TiO2, (e) 12% B-TiO2, (f) 14% B-TiO2.
Figure 3
Figure 3
(a) Low-resolution TEM images, (b) high-resolution lattice images, (c) EDS, (d) HAADF and EDS elemental mapping images of (e) B, (f) O, (g) Ti for the sample 10% B-TiO2.
Figure 4
Figure 4
(a) XPS survey spectra, (b) high-resolution B1s XPS spectra, (c,d) high-resolution O1s XPS spectra, (e,f) high-resolution Ti2p XPS spectra of all the prepared catalysts.
Figure 5
Figure 5
(a) RhB photodegradation curves in the absence or presence of prepared catalysts, and (b) the kinetics of RhB degradation, (c) cycling experiments of 10% B-TiO2, (d) XRD of the as-prepared and cycled 10% B-TiO2, active species trapping experiments over pure-TiO2 (e) and 10% B-TiO2 (f) under simulated sunlight illumination.
Figure 6
Figure 6
EPR spectra over pure-TiO2 and 10% B-TiO2 for detecting the Vacancy (a), •OH (b), and •O2− (c) radical species under simulated sunlight irradiation.
Figure 7
Figure 7
(a) UV−Vis diffuse reflectance spectra and Plot of (αhv)1/2 versus hν (inset), (b) PL spectra, (c) comparison of Efb potential variations, (d) illustration of band structure variations, (e) TP curves and (f) EIS results of all prepared catalysts.
Figure 8
Figure 8
The charge transfer tracking by photo-deposition: (a) Low-resolution TEM images, (b) high-resolution lattice images, (c) HAADF and EDS elemental mapping images of (d) Ag, (e) B, (f) O, (g) Ti for the sample 10% B-TiO2.
Figure 9
Figure 9
Schematic illustration of formation and charge-transfer processes in the Z-scheme heterojunction of B-doped A-TiO2/R-TiO2: (a) before contact, (b) after contact, (c) photogenerated charge carrier transfer process in Z-scheme mode.
See this image and copyright information in PMC

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