Surface defect engineering of Fe-doped Bi7O9I3 microflowers for ameliorating charge-carrier separation and molecular oxygen activation

Guo

ACS Sustainable Chem. Eng.

et al. 2021

Exploring novel 2D heterojunction photocatalysts with a wide spectral response and high active site exposure has been a huge challenge. A small-sized catalyst with high dispersibility has been considered an ideal model for maximizing active sites and increasing atomic efficiency. Herein, the 0D/2D Z-scheme heterojunction was designed by in situ solvothermal and subsequent calcination in air by integrating dopant and defect doubly modified CeO2 nanodots and g-C3N4 nanosheets (CNNS). Ultrafine cobalt-doped CeO2 nanodots (≈4 to 5 nm) with enriched oxygen vacancies (Co-CeO2–OVs) were uniformly and tightly anchored on the surface of CNNS to form a heterojunction. The density functional theory (DFT) calculations confirmed that cobalt dopants and oxygen vacancies form impurity energy states at the top of a valence band, thus narrowing the band gap. The optimized 0D/2D heterojunction showed a remarkable hydrogen production rate of ∼203.6 μmol/h, which was approximately 4.9- and 30.8-fold higher than that of CNNS (∼41.2 μmol/h) and CeO2 (∼6.6 μmol/h), respectively. Moreover, a large quantum yield of ∼8.94% was achieved at 420 nm. The 0D/2D heterojunction with a larger intimate area provided abundant reactive active sites and strong electron interactions to excite photogenerated carrier dynamics, and the doping and defect engineering could expand the light response range by regulating the electronic band structure. Strong evidence provided by experimental results and DFT calculations proved the Z-scheme charge transfer pathway. This work not only provided a novel approach to integrate 0D nanodots and 2D nanosheets for the formation of intimate Z-scheme heterointerfaces but also deepened the understanding of the dopant–defect synergistic modification to optimize the band structure and electronic structures for high-efficient solar energy capture and conversion.

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dopant and Defect Doubly Modified CeO₂/g-C₃N₄ Nanosheets as 0D/2D Z-Scheme Heterojunctions for Photocatalytic Hydrogen Evolution: Experimental and Density Functional Theory Studies

Guo

ACS Sustainable Chem. Eng.

et al. 2021

J of Chemical Tech & Biotech

“…Bi 7 O 9 I 3 is also a bismuth‐based semiconductor with the small band gap value of ca . 1.95 eV that has attracted much interest recently because it shows excellent visible‐light photocatalytic activity 20‐23 . However, the drawback of serious recombination of photogenerated charge carriers hinders BiO 7 O 9 I 3 from achieving the photocatalytic performance suitable for practical application.…”

Section: Introductionmentioning

confidence: 99%

“…1.95 eV that has attracted much interest recently because it shows excellent visible-light photocatalytic activity. [20][21][22][23] However, the drawback of serious recombination of photogenerated charge carriers hinders BiO 7 O 9 I 3 from achieving the photocatalytic performance suitable for practical application. Therefore, constructing heterojunction structures by combing BiO 7 O 9 I 3 and BiOIO 3 seems to be an effective strategy to simultaneously solve the problems of the low efficiency of electron-hole separation in BiO 7 O 9 I 3 and of the narrow light absorption spectra of BiOIO 3 .…”

Section: Introductionmentioning

confidence: 99%

Highly efficient removal of 2,4‐dichlorophenal over a novel dual Z‐scheme heterojunction of Bi₇O₉I₃/BiOIO₃/g‐C₃N₄ under visible‐light irradiation: performance and mechanism

You

Pan

et al. 2022

BACKGROUND 2,4‐Dichlorophenol (2,4‐DCP) is widely used as a preservative, pesticide, germicide, etc. However, it is very damaging to organisms and the environment, and it is difficult to decompose because of its high stability. To improve the photocatalytic ability of photocatalysts for degrading hazardous substances, like 2,4‐DCP, constructing heterojunction is an effective strategy because of its restraint of electron–hole recombination and extension of light absorption spectra. RESULTS A novel photocatalyst Bi7O9I3/BiOIO3/g‐C3N4 was successfully synthesized by one‐step in‐situ co‐crystallization method. The formation of Bi7O9I3/BiOIO3/g‐C3N4 composite was confirmed by X‐ray diffractometer (XRD), X‐ray photoelectron spectroscopy (XPS), fourier transform infrared spectrometer (FTIR spectrometer) and transmission electron microscope (TEM). The obtained optimal composite exhibited an excellent photocatalytic performance of degrading 2,4‐DCP with an efficiency of 95% under visible‐light irradiation. The trapping experiments indicated that superoxide radicals, electrons, and singlet oxygen played vital roles in 2,4‐DCP decomposition and confirmed the dual Z‐scheme heterojunction structure of Bi7O9I3/BiOIO3/g‐C3N4. Furthermore, the possible reaction pathway was deduced based on the trapping experiments and the intermediate products detected by liquid chromatography tandem mass spectrometry. CONCLUSION The photocatalytic performance of Bi7O9I3/BiOIO3/g‐C3N4 was enhanced because the more efficient separation and transfer of photogenerated charge carriers was achieved due to the formation of dual Z‐scheme heterojunction. This work presented a simple and feasible synthesis method to prepare a ternary photocatalyst for improving the photocatalytic ability, and it can assist in further understanding the reaction mechanism of 2,4‐DCP degradation. © 2022 Society of Chemical Industry (SCI).

“…Among them, the construction of heterojunction photocatalyst has been proved to be a reliable approach, which shows an improved photocatalytic property than the bare Bi 2 SiO 5 (Chai et al 2019). Bismuth-based oxide photocatalysts have been considered as an outstanding candidate for the visible light driven photocatalysts due to their excellent optical response over a wide spectral range (Jia et al 2021, Lu et al 2018a, Yu et al 2020. Compared with other Bi-based photocatalysts, bismuth oxide (Bi 2 O 3 ) has been proved to be an ideal photocatalyst with a narrow band gap and matching band potentials to form the heterojunction with Bi 2 SiO 5 (Hezam et al 2018, Xie et al 2020).…”

Section: Introductionmentioning

confidence: 99%

In-Situ Construction of Bi2O3/Bi2SiO5 Heterojunction Photocatalyst On The Exfoliated Bentonite With Efficient Photocatalytic Performance

Nie

Chen

Huang

et al. 2021

Preprint

In this study, Bi2O3/Bi2SiO5 heterojunction were in-situ constructed on the exfoliated bentonite via a novel one-pot method. The crystal structure, morphology, and optical features for the as-synthesized Bi2O3/Bi2SiO5 heterojunctions were systematically characterized by a series of characterization methods. During the preparation process, the exfoliated bentonite acted as the Si source and framework for the in-situ formation of Bi2O3/Bi2SiO5 p-n heterogeneous junction on the bentonite interlayer. As a result, the Bi2O3/Bi2SiO5 photocatalyst exhibited a superior photocatalytic performance than that of bare α-Bi2O3 toward the decomposition of Rhodamine B (RhB) via the simulated solar light irradiation, which was due to the synergetic effects of large specific surface areas and p-n junction between Bi2SiO5 and Bi2O3. Moreover, a probable photocatalytic mechanism for the as-prepared photocatalysts was explored. This work provides a new insight into building the cost-efficient photocatalysts for the contaminant degradation and a latent photocatalytic application of bentonite.