Novel S-scheme 2D/2D BiOBr/g-C3N4 heterojunctions with enhanced photocatalytic activity

Zhang, Bin; Hu, Xiaosong; Liu, Enzhou

doi:10.1016/s1872-2067(20)63765-2

Cited by 220 publications

(60 citation statements)

References 62 publications

(71 reference statements)

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“…[62] Liu and his colleagues constructed 2D/2D BiOBr/g-C 3 N 4 heterojunctions for RhB degradation. [63] Within 30 min, 99% of RhB (10 mg L −1 , 100 mL) was efficiently degraded when the weight ratio of BiOBr to g-C 3 N 4 is 1.5.…”

Section: Environmental Remediationmentioning

confidence: 98%

Emerging S‐Scheme Photocatalyst

et al. 2022

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strategies in addressing the low-efficiency issue will be discussed.Photocatalysis mainly deals with electron and energy transfer processes. Prior to the discussion, it is necessary to learn the basic behaviors of the excited state of a molecule, which can enhance the understanding on electron transfer and energy dissipation in semiconductors. Generally, the first process is the absorption of a photon by a molecule (in the time scale of femtoseconds (fs)), where the ground state is lifted energetically to the first excited singlet state. Subsequently, a simplified Jablonski diagram is reconsidered, [2] as shown in Figure 1. The charge carriers generated in one molecule experience several possible processes with varying possibilities: [3] a) Vibrational relaxation (VR): it is relaxation of excited state electrons to the lowest energy level which generally occurs in picoseconds (ps). It can happen from each excited state to each non-excited state including the ground state. This VR results in loss of energy because excessive vibrational energy is converted into heat. b) Fluorescence: After the relaxation to the lowest vibrational level, the excited molecule can finally get back to the ground state by emitting a photon. This is named as fluorescence, which occurs in a relatively long time, ranging from ps to nanoseconds (ns). c) Internal conversion (IC): it is a crossover process in which an electronically excited molecule moves from one electronic state to a lower one of the same multiplicity (singlet-to-singlet or triplet-to-triplet states) and can be measured from ps to fs. [4] d) Intersystem crossing (ISC): A transition from one electronic state to another one with a different spin multiplicity is called ISC. e) Phosphorescence: After the molecule transitions through ISC to the triplet state, further deactivation occurs through phosphorescence. And its lifetime ranges from one millisecond (ms) to hundreds of seconds. Apart from these, other processes such as vibrational cooling are also possible, which are not illustrated here.The above-mentioned processes in a single molecule can be used as a reference when discussing a semiconductor photocatalyst. Analogously, electrons are excited to the conduction band (CB) after absorption. Afterward, they will undergo several decay processes or they will finally migrate to the surface and participate in a specific redox reaction. These decay processes are briefly introduced here by comparing with those in a molecule (Figure 1): a) Relaxation of electrons to the lowest CB energy states. b) Radiative recombination of electrons and holes via emitted as fluorescence; c) Non-radiative decay, also referred to as Photocatalysis is a green technology to use ubiquitous and intermittent sunlight. The emerging S-scheme heterojunction has demonstrated its superiority in photocatalysis. This article covers the state-of-the-art progress and provides new insights into its general designing criteria. It starts with the challenges confronted by single photocatalyst from the perspective of...

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Section: Environmental Remediationmentioning

confidence: 98%

Emerging S‐Scheme Photocatalyst

et al. 2022

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“…5(b) was deconvoluted into two peaks located at about 529.9 and 530.8 eV which corresponded to BiO bonds and oxygen‐containing species adsorbed on surface, respectively 43 . In comparison with Bi 4 O 5 Br 2 , the Br 3d 5/2 and 3d 3/2 peaks of BC2 shifted from 68.7 and 69.8 eV to higher 68.8 and 69.9 eV, may due to the decreased electron cloud density of Bi 4 O 5 Br 2 after contact with BiOCl 44,45 . On the contrary, the Cl 2p 3/2 and 2p 1/2 peaks of BC2 shifted to lower binding energies compared with those of BiOCl.…”

Section: Resultsmentioning

confidence: 99%

“…43 In comparison with Bi 4 O 5 Br 2 , the Br 3d 5/2 and 3d 3/2 peaks of BC2 shifted from 68.7 and 69.8 eV to higher 68.8 and 69.9 eV, may due to the decreased electron cloud density of Bi 4 O 5 Br 2 after contact with BiOCl. 44,45 On the contrary, the Cl 2p 3/2 and 2p 1/2 Figure 1. XRD patterns of as-prepared samples.…”

Section: Characterization Of Samplesmentioning

confidence: 96%

Novel Z‐scheme 2D/2D Bi₄O₅Br₂/BiOCl heterojunction with enhanced photocatalytic activity for RhB degradation

Zhang

Xiao

2022

J of Chemical Tech & Biotech

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BACKGROUND With the rapid development of industry and commerce, organic pollutants such as RhB are detrimental to human health and living environment. As a promising technology for treating the organic pollutants in wastewater, photocatalysis technology has received worldwide attention. For practical application, a novel photocatalyst with superior photocatalytic activity should be developed. RESULTS A novel Bi4O5Br2/BiOCl (BC2) heterojunction photocatalyst with 2D/2D structure was fabricated via a facile one‐pot solvothermal method. Compared with pure Bi4O5Br2 and BiOCl, the BC2 heterojunction exhibited enhanced photocatalytic performance which reached 91% photodegradation efficiency for RhB under 120 min irradiation of simulated solar‐light at pH 7. And 99% RhB was degraded by BC2 under 60 min irradiation at pH 6. CONCLUSION According to experimental and characterization analytical results, the enhanced photocatalytic activity of Bi4O5Br2/BiOCl (BC2) heterojunction could be attributed to the following four points: (i) The BC2 heterojunction with excellent visible light response could effectively utilize the simulated solar‐light. (ii) The more negative surface electronegativity of BC2 favored the adsorption of RhB during the photodegradation process. (iii) The 2D/2D BC2 heterojunction had large interface region and internal electric field, thus it displayed superior carriers transfer capability and enhanced charge separation efficiency. (iv) The carriers transfer mechanism of Z‐scheme could hinder the recombination of photoinduced charge carriers and endow this photocatalyst with enough redox capacity to degrade RhB. Moreover, slightly acidic condition (pH 6) could promote degradation of RhB, due to the enhanced adsorption capacity of BC2 heterojunction. © 2022 Society of Chemical Industry (SCI).

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“…The conduction band (CD) edge of the electron transport layer also plays a vital role in improving the efficiency of solar cells. This edge was calculated by the following method [ 63 ]. ZnO has one Zn atom and one oxygen atom.…”

Section: Resultsmentioning

confidence: 99%

Photovoltaic Properties of ZnO Films Co-Doped with Mn and La to Enhance Solar Cell Efficiency

et al. 2022

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In the present investigation, ZnO films co-doped with Mn and La were synthesized by the sol–gel technique. XRD analysis revealed that ZnO had a hexagonal structure. Mixed hexagonal and cubic phases appeared in ZnO containing Mn (1%) and La (1.5%). The grain size, d-spacing, unit cell, lattice parameters, atomic packing fraction, volume, strain, crystallinity, and bond length of co-doped ZnO films were determined as a function of doped ion contents. Through UV analysis, it was found that pristine ZnO had Eg = 3.5 eV, and it decreased when increasing the doping concentration, reaching the minimum value for the sample with 1% Mn and 1% La. The optical parameters of the films, such as absorption, transmittance, dielectric constants, and refractive index, were also analyzed. DSSCs were fabricated using the prepared ZnO films. For pure ZnO film, the values were: efficiency = 0.69%, current density = 2.5 mAcm−2, and open-circuit voltage = 0.56 V. When ZnO was co-doped with Mn and La, the efficiency increased significantly. DSSCs with a ZnO photoanode co-doped with 1% Mn and 1% La exhibited maximum values of Jsc = 4.28 mAcm−2, Voc = 0.6 V, and efficiency = 1.89%, which is 174% better than pristine ZnO-based DSSCs. This material is good for the electrode of perovskite solar cells.

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Novel S-scheme 2D/2D BiOBr/g-C3N4 heterojunctions with enhanced photocatalytic activity

Cited by 220 publications

References 62 publications

Emerging S‐Scheme Photocatalyst

Emerging S‐Scheme Photocatalyst

Novel Z‐scheme 2D/2D Bi₄O₅Br₂/BiOCl heterojunction with enhanced photocatalytic activity for RhB degradation

Photovoltaic Properties of ZnO Films Co-Doped with Mn and La to Enhance Solar Cell Efficiency

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Novel S-scheme 2D/2D BiOBr/g-C3N4 heterojunctions with enhanced photocatalytic activity

Cited by 220 publications

References 62 publications

Emerging S‐Scheme Photocatalyst

Emerging S‐Scheme Photocatalyst

Novel Z‐scheme 2D/2D Bi4O5Br2/BiOCl heterojunction with enhanced photocatalytic activity for RhB degradation

Photovoltaic Properties of ZnO Films Co-Doped with Mn and La to Enhance Solar Cell Efficiency

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Novel Z‐scheme 2D/2D Bi₄O₅Br₂/BiOCl heterojunction with enhanced photocatalytic activity for RhB degradation