Transfer Of Electron-hole Pairs Research Articles

Construction of 0D Ti3C2Tx MXene nanoparticles sensitized 1D TiO2 nanotube arrays for enhanced photocatalytic and photoelectrochemical properties

Developing efficient photocatalysts with highly active facets and appropriate cocatalyst hybridization to form heterostructure is a valid way to expedite the separation of photoexcited electron-hole pairs. Herein, a novel 0D/1D Ti3C2Tx MXene/TiO2 photocatalyst was fabricated for photoelectrochemical (PEC) water splitting and tetracycline antibiotic photocatalytic degradation. Meanwhile, highly-exposed TiO2 nanotube arrays were prepared by electrochemical anodizing method, and Ti3C2Tx nanoparticles with mixed terminal group were uniformly grown on the surface of TiO2 through the hydrothermal and solvothermal process, respectively. Compared with pure TiO2, the Ti3C2Tx/TiO2 heterostructure exhibited different degrees of enhancement in PEC and photocatalytic degradation activities under simulated sunlight. The TNT/M-h sample yielded a photocurrent density of 1.77 mA cm−2 at 0 V (vs. SCE) and achieved a 95.57 % photocatalytic removal rate of tetracycline within 140 min. The excellent performance originated from the strong interfacial contact and work function discrepancy between the ordered tubular structure of TiO2 and 0D Ti3C2Tx nanoparticles, which realized the high-efficiency photogeneration and transfer of electron-hole pairs.

Visible-light photoreduction of Cr(VI) over CdIn2S4/MOF-808 composites

Although solar-light driven photocatalysis is a promising route to reduce Cr(VI) from wastewater, its challenge is to construct highly efficient and muti-functional photocatalysts. Herein, CdIn2S4 combined with MOF-808 (CIS/MOF-808) composites were prepared for boosting solar-light induced photoreduction of Cr(VI). The close contact between MOF-808 and CdIn2S4 was favorable for the separation and transfer of electron-hole pairs, and provided sufficient vacant sites of Cr(VI) adsorption and photon capture. The removal activity of Cr(VI) over CIS/MOF-808 hybrids was higher than pristine MOF-808 and CdIn2S4. CdIn2S4 content, pH, and inorganic salts affected the removal efficiency of Cr(VI) and the concentration of Cr3+ in aqueous solution. The removal efficiency of Cr(VI) over 4-CIS/MOF with a nominal CdIn2S4 content of 16 wt. % was 95.45 %, and declined to 88.17 % after five cycles. The acidic medium induced to the fast reaction between Cr(VI) and e− to form Cr(III), while deteriorated the metal leaching as well as photo-corrosion to restrain the photocatalytic activity.

Surface plasmon resonance-mediated photocatalytic H2 generation.

The limited yield of H2 production has posed a significant challenge in contemporary research. To address this issue, researchers have turned to the application of surface plasmon resonance (SPR) materials in photocatalytic H2 generation SPR, arising from collective electron oscillations, enhances light absorption and facilitates efficient separation and transfer of electron-hole pairs in semiconductor systems, thereby boosting photocatalytic H2 production efficiency. However, existing reviews predominantly focus on SPR noble metals, neglecting non-noble metals and SPR semiconductors. In this review, we begin by elucidating five different SPR mechanisms, covering hot electron injection, electric field enhancement, light scattering, plasmon-induced resonant energy transfer, and photo-thermionic effect, by which SPR enhances photocatalytic activity. Subsequently, a comprehensive overview follows, detailing the application of SPR materials-metals, non-noble metals, and SPR semiconductors-in photocatalytic H2 production. Additionally, a personal perspective is offered on developing highly efficient SPR-based photocatalysis systems for solar-to-H2 conversion in the future. This review aims to guide the development of next-gen SPR-based materials for advancing solar-to-fuel conversion.

Photogenerated carriers transfer in Pd/TiO2-AgO heterojunction and its photocatalytic behaviors on oxidative dehydrogenation of ethane to ethylene

Photocatalytic oxidative dehydrogenation of ethane to ethylene with a high selectivity is an attractive reaction. In this study, different types of heterojunctions between Pd/TiO2 and a second metal oxide semiconductor were designed and synthesized to realize high activity conversion of C2H6 to C2H4. Pd/TiO2-AgO heterojunction was proved with best reaction performance. The addition of AgO facilitated the activation of reactant molecules. It enhanced directional transfer of electron-hole pairs and separation efficiency of photogenerated carriers. Pd/TiO2-5 % AgO heterojunction was proved with the best separation ability of photogenerated carriers and the largest number of surface hydroxyl groups. Detailed charge transfer path and reaction mechanism were proposed and discussed.

Visible light driven Z-scheme α-MnO2 (1D)/Bi7O9I3 (2D) heterojunction photocatalyst for efficient degradation of bisphenol A in water

Z-scheme heterojunctions are gaining attention for their outstanding photocatalytic performance in degrading organic pollutants due to improved charge separation efficiency. In view of this, the present study is focused on the synthesis of novel 3D α-MnO2/Bi7O9I3 (MB) nanocomposites heterojunctions of varying α-MnO2 contents via facile in-situ chemical precipitation method at room temperature. Under optimum conditions, MB4 (comprising 485 mg of α-MnO2) exhibited exceptional performance, achieving about 97.5% of bisphenol A (BPA) degradation in 80 mins with a degradation rate constant of 0.08354 min−1. Such superior performance is attributed to efficient interfacial integration and charge separation, validated through various characterization techniques. Further, MB4 heterojunction facilitated Z-scheme electron-hole pair transfer and exhibited an augmented specific surface area. The active species involved in the degradation of BPA were identified as •O2– and •OH in scavenging experiments and supported by findings based on EPR. Additionally, degradation pathways and plausible BPA intermediates have been proposed based on LC-MS/MS studies. Furthermore, with an impressive mineralization rate (89.5%), the toxicity study unveiled less harmful intermediates than the parent compound BPA. MB4 photocatalyst also exhibited commendable stability, as evidenced by its studies based on five reuse cycles with 92.9% efficiency. In essence, visible-light-driven Z-scheme α-MnO2/Bi7O9I3 heterojunction photocatalyst offered a simple and sustainable approach for producing environmentally friendly materials, underscoring its potential in the removal of BPA in water and wastewater treatment.

Z-scheme heterojunction engineering and hole-extraction layer enable efficient photoelectrochemical water splitting on BiVO4 photoanode

This study presents a novel Z-scheme heterostructure that was developed by integrating three-dimensional CoFe2O4 nanospheres with Mo and W co-doped BiVO4 (MW:BVO). Subsequently, ultra-thin hydroxides (NiOOH-FeOOH) were grown on the surface of the MW:BVO@CFO photoanode in the presence of tannic acid (TA), resulting in the formation of MW:BVO@CFO/TANF photoanodes. Notably, TANF served as a hole extraction layer. Compared to pristine MW:BVO, the photocurrent density of MW:BVO@CFO/TANF photoanodes exhibited a significant enhancement from 0.96 mA/cm2 to 6.03 mA/cm2 at 1.23 VRHE with a charge separation efficiency of 90.2 % due to the synergistic effect of the Z-scheme structure and hole extraction layer. Notably, the Z-scheme architecture facilitates the effective separation and transfer of electron-hole pairs, thereby retaining electrons and holes with high redox capacity. Meanwhile, the hole extraction layer quickly exports and aggregates the photo-generated holes, thereby further improving the separation efficiency of electron-hole pairs.

Full-spectrum photocatalytic treatment and in situ upcycling of organophosphorus wastewater enabled by biomimetic urchin-like Bi2S3/CdS

High-efficiency photo-degradation organophosphorus pollutants into value-added chemicals, reducing or avoiding CO2 emission, is challenging but significant for environmental protection and carbon neutrality. Herein, a novel biomimetic urchin-like Bi2S3/CdS (BCS-UL) photocatalyst with full spectral response was developed for thorough degradation of glyphosate (Gly) and in situ upcycling into CO (731 μmol g-1h−1). Control experiments, finite element simulations, and theoretical calculations corroborated that Z-scheme heterojunction BCS-UL achieved highly photothermal/pyroelectric properties by multiple scattering and reflection of near-infrared light among spines of Bi2S3 component, which could promote the transfer of electron-hole pairs and regulate the selective formation of reactive oxygen species •O2–. The active center CdS component promoted C-P bond activation of Gly, which was more susceptible to being converted into sarcosine and further to CO by nucleophilic attack with •O2– and oxidation with h+. The decomposition pathways of Gly and acute toxicity of the intermediates were analyzed with LC-MS, Fukui index, and theoretical calculation. Moreover, BCS-UL was applicable for the efficient degradation of Gly at low concentrations over a wide pH range and could be recycled at least 5 times with no evident decline in catalytic activity. The biomimetic manufacturing technology provides a new avenue for implementing synchronously high-performance photocatalytic treatment and oriented upcycling of organic pollutants.

Novel 3D MIL-53(Fe)/graphene aerogel composites for boosted photocatalytic ibuprofen degradation under visible light: Process and mechanism

A highly efficiency process is urgently needed to remove the active pharmaceuticals contamination of water pollution. Herein, 3D MIL-53(Fe)/graphene aerogel (GMA) composites were designed to photodegrade ibuprofen (IBP) in the presence of persulfate (PS). The GMA composites exhibited high-speed electron-hole pairs transfer efficiency, higher specific surface area, excellent IBP degradation ability and easily recycling. The optimizing GMA-1 composite displayed a significant enhanced IBP photodegradation efficiency, in which the IBP degradation efficiency over GMA-1 reached closed to 100% within 60 min under visible light irradiation in the presence of PS. The effect of some vital anions were investigated. Furthermore, SO4·−, ·OH and ·O2− were identified as the main reactive species during the degradation of IBP. The photolytic degradation pathways of IBP and ecotoxicities of the intermediate products were also analyzed. This study may provide an alternative way for effectively removing IBP by 3D metal organic frameworks/graphene aerogel materials.

Photonics in Multimaterial Lateral Heterostructures Combining Group IV Chalcogenide van der Waals Semiconductors.

Lateral heterostructures combining two multilayer group IV chalcogenide van der Waals semiconductors have attracted interest for optoelectronics, twistronics, and valleytronics, owing to their structural anisotropy, bulk-like electronic properties, enhanced optical thickness, and vertical interfaces enabling in-plane charge manipulation/separation, perpendicular to the trajectory of incident light. Group IV monochalcogenides support propagating photonic waveguide modes, but their interference gives rise to complex light emission patterns throughout the visible/near-infrared range both in uniform flakes and single-interface lateral heterostructures. Here, this work demonstrates the judicious integration of pure and alloyed monochalcogenide crystals into multimaterial heterostructures with unique photonic properties, notably the ability to select photonic modes with targeted discrete energies through geometric factors rather than band engineering. SnS-GeS1-xSex-GeSe-GeS1-xSex heterostructures with a GeS1-xSex active layer sandwiched laterally between GeSe and SnS, semiconductors with similar optical constants but smaller bandgaps, were designed and realized via sequential vapor transport synthesis. Raman spectroscopy, electron microscopy/diffraction, and energy-dispersive X-ray spectroscopy confirm a high crystal quality of the laterally stitched components with sharp interfaces. Nanometer-scale cathodoluminescence spectroscopy provides evidence for a facile transfer of electron-hole pairs across the lateral interfaces and demonstrates the selection of photon emission at discrete energies in the laterally embedded active (GeS1- xSex) part of the heterostructure.

Decahedral BiVO4/tubular g-C3N4 S-scheme heterojunction photocatalyst for formaldehyde removal: Charge transfer pathway and deactivation mechanism

Designing a durable and efficient heterojunction photocatalyst for the removal of indoor air pollutants has attracted significant attentions. However, the interfacial charge transfer pathway and deactivation mechanism of photocatalysts are still challenges. In this study, the decahedral BiVO4/tubular g-C3N4 (BiVO4/TCN) S-scheme heterojunction photocatalyst was synthesized, which exhibited excellent photocatalytic activity and stability for the removal of formaldehyde (HCHO) in a continuous-flow reactor. The formation of the S-scheme heterojunction promoted spatial separation of charges, enhanced the redox capability, and maintained favorable charge carrier potentials. Based on Central Composite Design, a semi-empirical equation was successfully established to predict the removal efficiency of HCHO, and photocatalyst load and initial concentration played important roles in the removal of HCHO. The interfacial charge transfer pathway in the S-scheme heterojunction was clearly confirmed through photo-irradiated Kelvin probe and in situ irradiated X-ray photoelectron spectroscopy analysis. The superficial state changes of BiVO4/TCN before and after the reaction indicated that the formation of coke could inhibit separation and transfer of electron-hole pairs, resulting in a slight decrease in photocatalytic activity. In summary, this study not only presents an effective technology for constructing S-scheme heterojunction photocatalyst, but also offers a new insight on the deactivation mechanism of photocatalyst during removal of volatile organic compounds.

Synergistic effect of CuO coupled with MoS2 for enhanced photodegradation of organic dyes under visible light

A series of MoS2-modified CuO (CuO/MoS2) heterostructures were successfully fabricated. The photodegradation properties of organic dyes were explored in detail under visible light. The photocatalytic results demonstrate that the CuO/MoS2-3 heterostructure delivers superior degradation rates towards methyl violet dye (MV) and rhodamine B (RhB), reaching 99.8% and 95.3% within 30 min, respectively. The decent photodegradation activity is due to improved visible light adsorption and faster transfer of electron-hole pairs. The radical trapping experiments show that superoxide radicals (·O2-) and holes (h+) are the main active species in the removal of MV. Furthermore, the CuO/MoS2-3 composite possesses the prominent stability and recyclability. This work offers a highly sustainable technique for designing a high-efficiency photocatalyst to remove environmental pollutants.

Efficient photocatalytic simultaneous removal of organic and heavy metal complex pollutants under visible light by crystal-facet-mediated TiO2/Ti3C2-BiOBr nanocomposites

Developing regularly active facet-mediated catalysts remains an ongoing challenge to address rapid recombination and slow transfer of electron-hole pairs during photocatalytic removal of pollutants from water. Herein, crystal-facet-mediated TiO2/Ti3C2-BiOBr nanocomposites have been successfully fabricated by in situ growing active (001) facets exposed TiO2 nanosheets on highly conductive Ti3C2Tx MXene and then growing BiOBr with exposed facets ((102), (110) and (001)) on (001)TiO2/Ti3C2. The (001)TiO2/Ti3C2-BiOBr heterojunctions displayed remarkable enhancement in photocatalytic simultaneous removal of rhodamine B (RhB) and hexavalent chromium (Cr(VI)) complex pollutants under visible light. TB(102) that highly exposed (102) facets of BiOBr exhibited the best photocatalytic activities with the removal rates of RhB and Cr(VI) reaching 0.378 and 0.039 min−1, respectively, which also achieved 100 % RhB degradation and 69.7 % Cr(VI) reduction within 60 min under sunlight. The mechanism of photocatalytic process was unearthed based on experiment results and various characterizations. This study provides significant reference for improving the activity of photocatalyst through multiple strategies.

S-scheme polyimide aerogel/Bi4O5I2 heterojunction photocatalyst with improved degradation efficiency

Polymer has low migration ability of photogenerated carriers under photoexcitation, which severely limits the photocatalytic application. In this paper, S-type polyimide aerogel/Bi4O5I2 (tPIA/BOI) heterojunction photocatalysts under internal electric field are prepared by supercritical ethanol drying and in-situ solvothermal method. The large surface area (42.381 m2/g) and excellent hydrophilicity (64.11°) can provide more active sites for photocatalytic reactions and better dispersion in solution, which are conducive to the photodegradation of pollutants. The removal rate of tPIA/BOI on tetracycline (TC) aqueous solution can reach 91.3 %, and the photodegradation rate is 31 and 2 times than that of original tPIA and BOI. The internal electric field is generated by the matching of tPIA and BOI, which optimizes the separation and transfer of electron-hole pairs. Besides, the range of light absorption is expanded, thus greatly improving the degradation efficiency of the catalyst.

Nitrogen and sulphur co-doped carbon quantum dot integrated bismuth oxide nanocomposite for photocatalytic degradation and electrochemical sensing applications

This study developed a novel nitrogen and sulphur co-doped carbon quantum dot-modified bismuth oxide binary composite (N,S-CQD- Bi2O3) through a hydrothermal method. The binary composite was successfully evaluated for its solar light-assisted photocatalytic abatement of toxic refractory pollutants such as dyes (rhodamine B, xylenol orange and sunset yellow), pesticides (2,4-D and diuron) and pharmaceutical drug (tetracycline). It was also successfully applied for the electrochemical detection of aniline molecules. The structural, morphological, optical, and electrochemical properties of the developed photocatalyst were investigated by XRD, FESEM, TEM, UV–vis DRS, XPS, PL, CV, amperometry and impedance techniques. Among the three different weight percentage binary composites, the 5% N,S-CQD-Bi2O3 displayed maximum photocatalytic performance. In all cases, the binary heterojunction exhibited a degradation efficiency of over 90% by converting the harmful compounds into less harmful ones. The scavenger experiments showed the roles of ˙OH and O2−˙ radicals in the photodegradation. The improved photocatalytic behaviour was ascribed to the Z-scheme heterojunction formation, enhancements in visible light absorption, improved surface morphology and efficient separation and transfer of electron-hole pairs. The electrochemical detection method yields a LOD of 0.25 nM within the linear range of 5–35 nM. Real sample analysis of aniline also produces excellent results with outstanding reproducibility.

Acid-tailored self-assembled perylene diimide supramolecular for visible-light-driven activation of peroxymonosulfate towards efficient degradation of iohexol

The presence of iohexol (IOX) in the environment has attracted widespread attention. Acetic acid, hydrochloric acid, and nitric acid tailored self-assembled perylene diimides (PA, PC and PN) were prepared and utilized in different visible-light-driven activation of peroxymonosulfate (PMS/Vis) systems for the degradation of IOX. As an electron acceptor, PMS can significantly hinder the recombination of photogenerated electron-hole pairs. The removal rate of 5 mg/L IOX by PC/PMS/Vis system reached 99.1% at 30 min, which was 2.0 times and 1.3 times higher than that of PA/PMS/Vis and PN/PMS/Vis system. The boosted oxidation activity with PC was due to the pH dependence of perylene diimide (PDI) self-assembly and the small amount of Cl− (0.56%) absorbed on PC, which can promote the transfer of electron-hole pairs, change the surface charge distribution and energy band position, and enhance π-electron conjugation. Based on density functional theory and electrostatic potential calculation, the Cl− adsorbed on the surface of PDI brings an effect on the electrostatic potential distribution. Furthermore, the built-in intermolecular electric field leads to accelerated charge transfer of PDI. In the PC/PMS/Vis system, holes, singlet oxygen and superoxide radical were perceived as the dominant contributors. The degradation of IOX carried out via pathways of amide hydrolysis, amino oxidation, hydrogen abstraction, deiodination reaction, and OH attack. This work provides a new method for the pollution control of IOX and scientific guidance for the tailored self-assembly of organic supramolecules.

Construction of novel S-scheme LaFeO3/g-C3N4 composite with efficient photocatalytic capacity for dye degradation and Cr(VI) reduction

The novel LaFeO3/g-C3N4 composite system with S-scheme heterojunction was designed and prepared through the reasonable combination of admirable oxidation of LaFeO3 and robust reduction of g-C3N4, then treating the refractory organics and toxic heavy ions in water. The significant enhancement on the photocatalytic property not only derived from the sufficient active sites, but also originated from the extended life-span of charge carriers. Meanwhile, the three-dimensional structure and combined redox advantages of bicomponents helped the separation and transfer of electron-hole pairs, thus improving the photocatalytic performance. Upon these superior characters, the apparent rate constant of RB-19 degradation by LaFeO3/g-C3N4 composite was 2.3 times than that of LaFeO3 and 24.8 times than that of g-C3N4. While that for Cr(VI) reduction was calculated as 0.0172, which was 4.8 times than that of LaFeO3 and 10.3 times than that of g-C3N4. Satisfyingly, in the simulation tests with adding different inorganic metal ions or surfactants into the water environments, this nice system of LaFeO3/g-C3N4 exhibited the excellent practical stability, a proof that its application prospect was promising. Moreover, our study provides the efficient avenue to design and explore the novel heterojunction photocatalyst.

Plant-based green fabrication of CuO-CdO-bentonite S-scheme heterojunction with enhanced photocatalytic performance for the degradation of levofloxacin.

In this research, for the first time, CuO and CdO nanoparticles (NPs) were synthesized using Ferula persica and anchored on layered bentonite as a novel S-scheme nano-heterojunction (denoted as CuO-CdO-BT). Ferula persica acted as a naturally-sourced reducing agent and stabilizer for the synthesis of NPs. The performance of CuO-CdO-BT was evaluated for the degradation of levofloxacin from an aqueous solution under sunlight. The characterization results clarified that the bentonite as a support not only reduced the agglomeration of CuO and CdO NPs but also decreased the size of biosynthesized NPs, which increased the active surface of NPs and the photodegardation efficiency. The effect of operational reaction system variables was examined to optimize the photocatalytic capability of CuO-CdO-BT. Under optimum conditions (catalyst dosage = 0.4g/L, LVF concentration = 10mg/L and pH = 8), 96.11% of levofloxacin was degraded using CuO-CdO-BT after 30min with degradation kinetic of 0.108min-1, which was about 2.4 and 4.2 times higher than those of bare CuO and CdO NPs, respectively. The improvement of the photocatalytic degradation efficiency of CuO-CdO-BT compared to CuO and CdO NPs was due to preventing the recombination of charge carriers in the S-scheme system. The radical quenching experiments ascertained the generation of [Formula: see text]·OH, and [Formula: see text] species in the CuO-CdO-BT system, indicating that ·OH radicals have a more prominent role than [Formula: see text] and [Formula: see text] in the photocatalytic reaction. The six possible levofloxacin pathways of LVF degradation were suggested based on HPLC-MS analysis. Over 88.5% LVF was removed using CuO-CdO-BT after three catalyst reuse cycles, indicating a cost-effectiveness potential of the biosynthesized photocatalyst reusability. Almost complete mineralization of LVF was obtained by the CuO-CdO-BT photocatalyst after 180min of reaction. Based on findings, the S-scheme mechanism of photo-generated electron-hole pairs transfer in the CuO-CdO-BT system was found. The unique structural features of the new generation of S-scheme heterojunction and green synthesis of NPs using plants provide promising photocatalysts to improve wastewater treatment.

Green synthesis of SiO2 from Equisetnm arvense plant for synthesis of SiO2/ZIF-8 MOF nanocomposite as photocatalyst

Equisetnm arvense plant extract was used for preparing amorphous SiO2. For preparing of SiO2/zeolitic imidazolate framework-8 (ZIF-8) nanocomposite by solvothermal method, the synthesized SiO2 was added to synthesis mixture ZIF-8. The photocatalytic activity of SiO2/ZIF-8 was investigated systematically by degrading crystal violet as a cationic dye under UV light irradiation. The photodegradation of crystal violet by SiO2, ZIF-8 and SiO2/ZIF-8 samples was 13.7%, 25.6% and 75.6% during UV-light irradiation for 15 min. Among synthesized samples (SiO2, ZIF-8 and SiO2/ZIF-8), the SiO2/ZIF-8 exhibited highest photocatalytic activity and improved stability compared to pure SiO2 and ZIF-8. As evidenced from SEM and TEM images, ZIF-8 particles without aggregation located over SiO2. The enhancement of the photocatalytic activity is due to the fact that the introduction of insulator SiO2 in SiO2/ZIF-8 composites can modify the surface state of the composite; more importantly, the energy level of SiO2 can help accelerate the separation and transfer of electron-hole pairs of ZIF-8. The SiO2/ZIF-8 photocatalyst did not show any obvious loss of photocatalytic activity during five cycles, which indicate that the heterostructured photocatalyst was stable and can be used repeatedly.

Heterostructure-Engineered Semiconductor Quantum Dots toward Photocatalyzed-Redox Cooperative Coupling Reaction.

Semiconductor quantum dots have been emerging as one of the most ideal materials for artificial photosynthesis. Here, we report the assembled ZnS-CdS hybrid heterostructure for efficient coupling cooperative redox catalysis toward the oxidation of 1-phenylethanol to acetophenone/2,3-diphenyl-2,3-butanediol (pinacol) integrated with the reduction of protons to H2. The strong interaction and typical type-I band-position alignment between CdS quantum dots and ZnS quantum dots result in efficient separation and transfer of electron-hole pairs, thus distinctly enhancing the coupled photocatalyzed-redox activity and stability. The optimal ZnS-CdS hybrid also delivers a superior performance for various aromatic alcohol coupling photoredox reaction, and the ratio of electrons and holes consumed in such redox reaction is close to 1.0, indicating a high atom economy of cooperative coupling catalysis. In addition, by recycling the scattered light in the near field of a SiO2 sphere, the SiO2-supported ZnS-CdS (denoted as ZnS-CdS/SiO2) catalyst can further achieve a 3.5-fold higher yield than ZnS-CdS hybrid. Mechanistic research clarifies that the oxidation of 1-phenylethanol proceeds through the pivotal radical intermediates of •C(CH3)(OH)Ph. This work is expected to promote the rational design of semiconductor quantum dots-based heterostructured catalysts for coupling photoredox catalysis in organic synthesis and clean fuels production.

Halogen doped g-C3N4/ZnAl-LDH hybrid as a Z-scheme photocatalyst for efficient degradation for tetracycline in seawater

The present research centered on the fabrication of halogen (F and Cl) doping g-C3N4 modified ZnAl-LDH (FCCN/LDH) nanohybrids and its application in the photodegradation of tetracycline (TC) in artificial seawater. Halogen doping g-C3N4 was prepared via hydrothermal and thermal polycondensation methods using melamine as the precursor. Heterostructural FCCN/LDH binary nanocomposites were synthesized by a facile co-precipitation process. The morphological analysis of binary heterojunction exhibited uniformed decoration of FCCN on the LDH nanosheet surface. FCCN/LDH hybrid displayed enhanced photocatalytic degradation efficiency in the artificial seawater compared with pure FCCN and LDH, which is attributed to appropriate band alignment and Z-scheme electron-hole pairs transfer mechanism to suppress the recombination of photogenerated charge carriers. Electrochemical properties and PL results confirmed the proposed mechanism for extended visible-light response range over FCCN/LDH nanocomposites. Finally, the degradation efficiency of other pollutants (MB, MO, CIP, Rh B, and Cr(VI)) and the photocatalytic stability over FCCN/LDH nanocomposites in the seawater system were also reconnoitered. The plausible Z-scheme mechanism signposted that h+ and O2– active species are foremost free radicals that play a pivotal role in photodegradation.