Z-scheme Heterostructure Research Articles

W/Mo-heteropoly blue-modified defective W18O49 as Z-Scheme heterostructure photocatalysts for efficient N2 fixation

Photocatalytic N2 fixation can convert the abundant but inert N2 into NH3 under atmospheric conditions. However, the dissatisfactory yield rate of NH3 greatly hinders its development. The rational design of a highly efficient N2 fixation photocatalyst enables large-scale ammonia production but is challenging due to the thermodynamic obstacles of N2 activation. Herein, the W/Mo-heteropoly blue modified defective W18O49 heterojunction composite catalysts (r-HPW/W18O49 and r-HPMo/W18O49) are prepared for N2 photofixaiton without sacrificial agents and cocatalysts under ambient conditions for the first time. The heteropoly blue nanoparticles are loaded on the surface of W18O49 by electro-reduction and subsequent solvothermal methods. The as-fabricated r-HPW/W18O49 show unusual activity with NH3 formation rates of 184.54 µmol g−1 h−1, about 2.6 times higher than that of initial W18O49. The excellent photocatalysis property is attributed to the synergistic effect between W18O49 and heteropoly blues. The defective W18O49 provides rich active sites for the effective adsorption of N2 molecules and acts as a robust support to inhibit the aggregation of heteropoly blues. The photo-generated electrons in W18O49 quickly transfer to the heteropoly blues, retarding charge pair recombination and enabling the constructed “Z-Scheme” heterostructure to stronger redox capacity. This work offers a new perspective for preparing advanced heteropoly blues-based N2 photofixation nanomaterials.

Boosting light harvesting and charge separation over hollow double-shelled Ag@SrTiO3-TiO2 with Z-scheme heterostructure for highly efficient photocatalytic reduction of nitrate to N2

Hollow double-shelled Ag@SrTiO3-TiO2 with Z-scheme heterostructure was constructed for highly efficient photocatalytic reduction of nitrate to N2. The 3D finite-difference-time-domain analysis indicated that hollow double-shelled structure improved light harvesting due to multiple reflections. Photo-generated electrons transfer from SrTiO3 to Ag0 caused by electron sink effect were utilized to reduce nitrate, while photo-generated electrons of TiO2 migrated to SrTiO3 via transport bridge of Ti3+ defects for electron–hole recombination. Such charge carriers migration pathway facilitated the construction of Z-scheme heterostructure, which enhanced charge separation yet still retained high redox powers. Both photogenerated electrons and CO2− played important role in photocatalytic denitrification. Furthermore, Ag0 acted as co-catalyst which not only promoted photogenerated electrons transfer to nitrate but also enhanced nitrate conversion selectivity to N2. Combining the above advantages, nitrate removal rate and the nitrogen selectivity reached 97.2 % and 98.8 % within 60 min, respectively. Even after five cycles, it still remained satisfied photocatalytic activity and stability. In summary, this work proposed a feasible strategy to construct Z-scheme hollow double-shelled photocatalyst for efficient photocatalytic denitrification.

Synergetic interfacial charge transfer with Z-scheme heterostructure and S–Mo–S linkage in one-pot synthesized SnIn4S8/MoS2 for efficient photocatalytic activity

Construction of high-efficiency scheme towards interfacial charge transfer is of great value to suppress the spatial carrier recombination and thus to develop advanced heterogeneous photocatalysts for environmental remediation. Herein, a novel Z-scheme SnIn4S8/MoS2 with interfacial S–Mo–S bond was synthesized by a facile one-step hydrothermal method. The prepared optimal SnIn4S8/MoS2 heterostructure (SIS/MS-24) exhibited significantly enhanced visible-light photocatalytic activities for crystal violet degradation and Cr(VI) reduction compared with individual materials. The boosted photocatalytic performance was primarily attributed to the Z-scheme charge transfer mechanism certificated by the trapping experiments, ESR (electron spin resonance) test, and DFT (density functional theory) calculation. What’s more, the formation of S–Mo–S bond between SnIn4S8 and MoS2 acted as a specific bridge to further promote the Z-scheme channel for charge transport at the interface. This synergy of Z-scheme heterostructure and covalent S–Mo–S linkage greatly accelerated the separation of electron-hole pairs. Additionally, the SIS/MS-24 composite also displayed good stability even after five cycles of testing experiments. This work provides a novel way to design and fabricate efficient Z-scheme photocatalysts for water purification.

Fabricating metal-free Z-scheme heterostructures with nitrogen-deficient carbon nitride for fast photocatalytic removal of acetaminophen

Photocatalytic technology has been increasing explored for the elimination of pollutants from aquatic environments. However, constructing powerful photocatalyst to drive rapid decontamination remains challenging. Here, we assemble boron-doped nitrogen-deficient carbon nitride (BNCN) into metal-free Z-scheme heterojunction via a facile approach to boost photocatalytic degradation of acetaminophen. Incorporating boron dopants and nitrogen defects to C3N4 significantly increase the photoabsorption. Furthermore, the constructed heterojunction exhibited decreased band gap and remarkably enhanced separation efficiency of photogenerated carriers compared with individual BNCN. Owing to the modulation of band structures and the better separation of photogenerated carriers, acetaminophen conversion approaching 100 % was achieved in just 30 mins under simulated sunlight, outperforming equivalent quantities of bulk carbon nitride and commercial TiO2 by 3.1 and 2.7 times, respectively. Two possible photodegradation pathways were proposed with hydroxylation and ring-opening reactions as dominant degradation reactions. Our findings provide an instructive catalyst design strategy to boost photocatalytic degradation efficiency.

Vacancy-Mediated Z-Scheme Heterostructure in SnO2-Decorated Spinel In3-xS4 with Boosted Photocatalytic Activity.

The widespread application of dyes and heavy metals causes increasing environmental pollution. One effective way to mitigate environmental pollution is to use semiconductor photocatalysts for redox purification of pollutants. Heterostructured photocatalysts can reduce the electron-hole recombination rate and improve light utilization. In this work, a novel SnO2/In3-xS4 composite with oxygen vacancy defect-mediated Z-scheme heterostructure is constructed for the first time by a one-pot method, in which SnO2 ultrasmall nanocrystals are decorated on nanopetals of flower-like In3-xS4. Material analyses show that the as-built three-dimensional hierarchical architecture is able to essentially increase the specific surface area and thus the active sites of the products. More importantly, the formation of Z-scheme heterojunction between the oxygen vacancy-induced SnO2 defect level and the In3-xS4 band structure not only promotes the separation of photogenerated charges but also makes them more reactive. Through the optimization of the composition ratio between the two phases, the visible-light-driven photocatalytic reaction rates of rhodamine B degradation and Cr(VI) reduction for the developed SnO2/In3-xS4 composite photocatalyst are 12.8 and 6.3 times of bare In3-xS4 and 32.0 and 76.0 times of bare SnO2, respectively. This work should provide a promising implication for designing new high-performance composite photocatalysts.

Adsorption and photocatalytic degradation of oilfield produced water by visible-light driven superhydrophobic composite of MIL-101(Cr)/Fe3O4-SiO2: Synthesis, characterization and optimization

A visible-light driven superhydrophobic composite of MIL-101(Cr)/Fe3O4-SiO2 was synthesized via hydrothermal method. Various physicochemical techniques were employed for the characterization of the nanoparticles such as XRD, FTIR, FESEM, TEM, EDS, BET, UV–Visible DRS, PL, and pHpzc. The adsorption and photocatalytic performance of the synthesized nanoparticles were evaluated by synthetic and real oilfield produced water (OPW) treatment. The optimal loading amount of Fe3O4-SiO2 was determined by analysis tests and investigation of photocatalytic activity. The results showed that the superhydrophobic composite with 35% weight percent of Fe3O4-SiO2 exhibited the maximum removal efficiency. Effect of operational parameters such as pH, reaction time, and initial concentration of pollutants on the removal efficiency were evaluated. The chemical oxygen demand (COD) removal efficiency of synthetic oilfield produced water (SOPW) achieved 95.17% and 96.6% under visible and UV light irradiation by MIL-101(Cr)/Fe3O4-SiO2 (35%), at the optimum conditions of pH 4, photocatalyst dosage 0.5 g/L, COD initial concentration 600 mg/L, and illumination time 150 min. Moreover, the gas chromatography-mass spectroscopy (GC–MS) analysis results showed 97.7% and 99.2% removal efficiency of total petroleum hydrocarbons (TPH) for real and synthetic OPW, respectively. The results of kinetic and isotherm study showed that the kinetic data followed the pseudo-second-order and equilibrium adsorption was described by the Freundlich model. The high specific surface area, narrow bandgap energy as well as the charge carrier separation based on the Z-scheme heterostructure caused the improvement of binary composite photocatalyst features. The results demonstrated that the MIL-101(Cr)/Fe3O4-SiO2 superhydrophobic composite are promising photocatalyst in the degradation of oilfield produced water pollutants. Synergistic effect of adsorption and photocatalytic degradation of OPW help to enhance the removal performance.

PtSe2/SnS2 heterostructure as a direct Z-scheme photocatalyst for water decomposition

The direct Z-scheme heterostructure has attracted much attention due to its strong photocatalytic ability. In the present work, we use density functional theory to explore the electronic and optical properties and photocatalytic mechanism of PtSe2/SnS2 heterostructure. Compared with PtSe2 and SnS2 monolayers, PtSe2/SnS2 heterostructure has smaller band gap and better light absorption capacity. The results of band calculation show that the heterostructure form a band arrangement of type-II. Further work function calculations indicate that the direction of the built-in electric field is PtSe2 to SnS2, indicating the charge transfer mechanism is Z-scheme. In the water decomposition reaction, the free energy calculation results show that water decomposition reaction can occur spontaneously under light. Therefore, PtSe2/SnS2 heterostructure can be used as a potential Z-scheme photocatalyst for hydrogen and oxygen production.

The interface design of (0D/2D/1D) AgI/BiOI/C3N5 dual Z-scheme heterostructures with efficient visible-light-driven photocatalytic activity

Given the present synthesis method of constructing a dual Z-scheme photocatalytic system, the accurate interface structure design remains a challenge. In this work, 0D/2D/1D AgI/BiOI/C3N5 dual Z-scheme heterojunctions with confined interface structures were fabricated by combining a room-temperature precipitation strategy with an ion-exchange route. Tetracycline hydrochloride (TCH) photodegradation under simulated visible light illumination was conducted to evaluate the photocatalytic activity of the as-prepared dual Z-scheme heterojunctions. Compared with the single component as well as the counterpart single Z-scheme heterojunctions, the constructed dual Z-scheme heterojunctions displayed superior catalytic activity. The apparent kinetic constant of the optimized AgI/BiOI/C3N5 nanocomposite was 410.2, 3.2 and 2.1 times as high as the bare C3N5, BiOI and AgI. The enhanced photocatalytic activity was attributed to the efficient charge separation of dual Z-scheme photocatalytic mechanism supported by systematical characterizations. It is anticipated this work can be a guide for the construction of a dual Z-scheme photocatalytic system.

Construction of 3D porous BiOBr/MIL-101(Cr) Z-scheme heterostructure for boosted photocatalytic degradation of tetracycline hydrochloride

The challenge for efficient photocatalysis lies in the adsorption, reuse capacity and charge separation. Herein, we constructed a Büchner funnel-like three-dimensional (3D) porous BiOBr/MIL-101(Cr) Z-scheme heterostructure with large specific surface area by immobilizing BiOBr on MIL-101(Cr) framework. The BiOBr/MIL-101(Cr) hybrids exhibited efficient charge separation and increasing adsorption capacity. Importantly, Bi and Cr atoms formed an electron donor-acceptor system, which benefits to induce internal electric field (IEF) to construct Z-scheme heterostructures for promoting charge transfer and separation. In addition, MIL-101(Cr) allows the continued growth of BiOBr in the presence of (001) direction, thus exposing more (001) facet of BiOBr, which helps the electron transfer from (110) to (001) and accelerates the carrier separation. Meanwhile, the formation of 3D pore structure endowed the BiOBr/MIL-101 (BM-35, which contained 35 wt% MIL-101) with twice higher adsorption capacity than pure BiOBr. Tetracycline hydrochloride (TC-HCl) was chosen as the target pollutant to evaluate the photocatalytic performance of the as-prepared BM-35 under visible light irradiation, 94 % degradation rate of TC-HCl was achieved over BiOBr/MIL-101(Cr) after 100 min and maintained at 84 % after 5 cycles. The small pores of MIL-101(Cr) only enable water molecules to pass through, while TC-HCl cannot enter its inner pores. Moreover, the formation of BiOBr by sheet stacking has large pores that capture target pollutants onto the highly active surface and decompose them. Benefiting from the distinctive 3D structure, an adsorption-degradation cycle system was formed, the difficulty of MOF desorption was effectively overcome.

Synergy of Z-scheme heterostructure with interfacial S−O bonding in In2S3/BiOBr for efficient tetracycline hydrochloride degradation and Cr(VI) reduction

High-efficiency interfacial charge transfer is the key to achieve better spatial carrier separation, and thus to develop advanced heterogeneous photocatalysts for environmental remediation. However, It still remains a great challenge to design and exploit the effective charge transfer scheme. Herein, a novel Z-scheme In2S3/BiOBr with S−O covalent bonding was prepared by hydrothermal and subsequent thermal annealing methods. The obtained photocatalysts were systematically characterized and used for tetracycline hydrochloride degradation and Cr(VI) reduction in aqueous solution. As a result, the optimized In2S3/BiOBr heterostructure (IS/BOB-39) exhibited superior photocatalytic activities for tetracycline hydrochloride degradation and Cr(VI) reduction under simulated solar light irradiation compared with individual materials. The Z-scheme transfer mechanism was corroborated by trapping experiments, ESR and XPS analysis, which provided an effective transfer pathway for spatial separation of carriers. Moreover, the formation of chemical S−O bond between In2S3 and BiOBr, which acted as a specific bridge to expediently transmit interfacial electrons, showed a synergistic effect with Z-scheme transfer model on the significantly enhanced photocatalytic performance. In addition, the In2S3/BiOBr heterojunction presented excellent cycle stability, resulting from the tight heterointerface. This work provides a promising approach to design and fabricate high effect Z-scheme heterojunction in wastewater treatment.

Constructing tightly integrated conductive metal-organic framework/covalent triazine framework heterostructure by coordination bonds for photocatalytic hydrogen evolution

The construction of tightly integrated heterostructures with metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) has been confirmed to be an effective way for improved hydrogen evolution. However, the reported tightly integrated MOF/COF hybrids were usually limited to the covalent connection of COFs with aldehyde groups and NH2-MOF via Schiff base reaction, restricting the development of MOF/COF hybrids. Herein, a covalent triazine framework (CTF-1), a subtype of crystalline COFs, was integrated with a conductive two-dimensional (2D) MOF (Ni-CAT-1) by a novel coordinating connection mode for significantly enhanced visible-light-driven hydrogen evolution. The terminal amidine groups in the CTF-1 layers offer dual N sites for the coordination of metal ions, which provides the potential of coordinating connection between CTF-1 and Ni-CAT-1. The conductive 2D Ni-CAT-1 in Ni-CAT-1/CTF-1 hybrids effectively facilitates the separation of photogenerated carriers of CTF-1 component, and the resultant hybrid materials show significantly enhanced photocatalytic hydrogen evolution activity. In particular, the Ni-CAT-1/CTF-1 (1:19) sample exhibits the maximum hydrogen evolution rate of 8.03 mmol g−1h−1, which is about four times higher than that of the parent CTF-1 (1.96 mmol g−1h−1). The enhanced photocatalytic activity of Ni-CAT-1/CTF-1 is mainly attributed to the incorporation of conductive MOF which leads to the formation of a Z-Scheme heterostructure, promoting the electron transfer in hybrid materials. The coordinating combination mode of Ni-CAT-1 and CTF-1 in this work provides a novel strategy for constructing tightly integrated MOF/COF hybrid materials.

Bismuth Tungstate-Silver Sulfide Z-Scheme Heterostructure Nanoglue Promotes Wound Healing through Wound Sealing and Bacterial Inactivation.

Rapid wound closure and bacterial inactivation are effective strategies to promote wound healing. Herein, a versatile nanoglue, bismuth tungstate (Bi2WO6)-silver sulfide (Ag2S) direct Z-scheme heterostructure nanoparticles (BWOA NPs), was designed to accelerate wound healing. BWOA NPs' hollow structure and rough surface could effectively close wound tissues acting as a barrier between external bacteria and the wound. More importantly, the unique Z-scheme heterostructure endows BWOA NPs with an effective electron and hole separating ability with potent redox potential, where electrons and holes could effectively react with water and oxygen to produce reactive oxygen species, leading to a higher antibacterial activity against both endogenous and external bacteria at the wound site. A series of in vitro and in vivo biological assessments demonstrated that BWOA NPs could rapidly close wounds and promote wound healing. With sunlight irradiation, the inhibiting rates of BWOA NPs against Escherichia coli and Staphylococcus aureus are 61.62 ± 2.85 and 73.40 ± 3.28%, respectively. Also, the wound healing rate in BWOA NP-treated mice is 25.90 ± 5.85% higher than PBS. This design provides a new effective strategy to promote bacterial inactivation and accelerate wound healing.

Novel dual Z-scheme Bi/BiOI-Bi2O3-C3N4 heterojunctions with synergistic boosted photocatalytic degradation of phenol

Photocatalysis is an emerging technique for the remediation of refractory organic contaminants. Herein, a novel dual Z-scheme Bi/BiOI-Bi2O3-C3N4 heterojunctions were constructed through a calcining process following with I− etching and UV-reduction processes. Various analytical technologies were adopted to characterize the materials. As a result, the Bi0 decorated composite presented improved visible-light-response and rapid charge transfer. Due to the synergy of Bi0 and dual Z-scheme heterostructures, a remarkable photocatalytic performance toward phenol degradation was achieved with the highest degradation efficiency of 93.2% and rate constant of 0.0161 min−1 over the optimal composite within 75 min of visible light irradiation. Interestingly, the concentration of the yielded benzoquinone considerably decreased with the introduction of C3N4. Trapping experiments and electron spin resonance (ESR) tests indicated that h+, O2−, OH and e− contributed to phenol remediation, and h+ and O2− were the crucial species toward phenol degradation. Furthermore, outstanding stability was obtained only with a decline of 3.8% after 4 cycles. A reasonable charge transfer mechanism was also proposed. This work provides a new route for in situ construction of Bi0 decorated dual Z-scheme heterojunction for phenolic compounds degradation.

Insights into Photocatalytic Degradation Pathways and Mechanism of Tetracycline by an Efficient Z-Scheme NiFe-LDH/CTF-1 Heterojunction.

Photocatalysis offers a sustainable approach for recalcitrant organic pollutants degradation, yet it is still challenging to seek robust photocatalysts for application purposes. Herein, a novel NiFe layered double hydroxide (LDH)/covalent triazine framework (CTF-1) Z-scheme heterojunction photocatalyst was rationally designed for antibiotics degradation under visible light irradiation. The NiFe-LDH/CTF-1 nanocomposites were readily obtained via in situ loading of NiFe-LDH on CTF-1 through covalent linking. The abundant coupling interfaces between two semiconductor counterparts lay the foundation for the formation of Z-scheme heterostructure, thereby effectively promoting the transfer of photogenerated electrons, inhibiting the recombination of carriers, as well as conferring the nanocomposites with stronger redox ability. Consequently, the optimal photocatalytic activity of the LDH/CTF heterojunction was significantly boosted for the degradation of a typical antibiotic, tetracycline (TC). Additionally, the photodegradation process and the mineralization of TC were further elucidated. These results envision that the LDH/CTF-1 can be a viable photocatalyst for long-term and sustainable wastewater treatment.

Efficient photocatalytic production of hydrogen peroxide by Z-scheme resorcinol-formaldehyde resin/g-C3N4 heterostructure under visible light

Photocatalytic production of hydrogen peroxide (H2O2) in pure water system under visible light is very desirable. Resorcinol-Formaldehyde (RF) resin has proven to be a promising photocatalyst for this purpose because of its high solar-to-chemical conversion (SCC) (∼0.5 %). However, RF resin prepared at low hydrothermal temperature is not satisfactory because the CO group, which is detrimental to the H2O2 production will only be generated when it is >250 °C. Herein, we successfully prepared a Z-scheme heterostructure between RF resin and g-C3N4 by mechanochemical method. The ball milled RF-g-C3N4 (RF-CN-bm) not only achieved CO group at a lower temperature (180 °C) but also produced as high as 72.86 umol H2O2 in 12 h under visible light, which is 2.37 times higher than that of bare RF resin. Moreover, we found that Z-scheme heterojunction was formed between RF and g-C3N4, which allowed the H2O2 production both through O2 reduction by CB e− of g-C3N4 and the combination of ∙HO that produced by oxidation of OH– by VB h+ of RF. In principle, the mechanochemical assembled RF-CN-bm developed in this study paves a new way for low-cost and high-performance H2O2 production under visible light.

Unraveling charge transfer pathways and mechanisms in CdS@CoWO4 Z-scheme heterojunction photocatalysts for high-efficiency environmental remediation

Recently, direct Z-scheme heterojunction catalysts have become an important hotspot in photocatalytic applications due to their much stronger redox capabilities. Novel direct Z-scheme CdS@CoWO4 spherical heterojunction photocatalysts were ingeniously designed and synthesized herein. The structural characterization and morphology analysis demonstrated that homogeneous heterojunctions between CdS and CoWO4 were indeed formed in the composite photocatalysts. Moreover, CdS@CoWO4 heterojunction photocatalysts exhibited excellent degradation capability towards refractory micropollutants (Pharmaceutical intermediates, dyes, and industrial additives, etc) in wastewater. Especially, the strongest photocatalytic activity reflected by the highest reaction kinetic parameter (k = 8.13 × 10−2 min−1) was observed in the CdS-2CoWO4 catalyst with the mass ratio of CdS:CoWO4 = 1:2, which is nearly 4 and 58 times as high as that of pure CdS (k = 2.21 × 10−2 min−1) and CoWO4 (k = 1.39 × 10−3 min−1), respectively. First-principles study combined with the radical species trapping experiments revealed that the charge transfer pathways and mechanisms in these heterojunctions favor the direct Z-scheme rather than the traditional Type-II mode. A key built-in electric field formed at the contact interfaces of CdS and CoWO4 drives the Z-scheme charge transfer mechanism, which strengthens the redox capacity of photogenerated carriers and ultimately greatly enhances the photocatalytic activity of the heterojunction catalysts. It is worth applauding that CdS and CoWO4 can form such Z-scheme heterostructures in a wide span of component ratios, which is of great benefit for their practical applications in environmental remediation.

FeIn2S4/Bi2MoO6 Z-scheme heterostructural composites efficiently degrade tetracycline hydrochloride under visible light

Antibiotics have gradually become a new pollutant in water, which seriously threatens human health. The development of efficient and easily recyclable photocatalysts is urgently needed to achieve water purification. Herein, a novel FeIn2S4/Bi2MoO6 Z-scheme heterostructural composite is successfully synthesized by a simple heat-shrinkable polymerization solvothermal method. When the doping FeIn2S4 mass fraction is 10%, the degradation rate of tetracycline hydrochloride (TCH) is the highest, reaching 83.25%, which is 1.97 and 2.38 times higher than that of pure FeIn2S4 and Bi2MoO6, respectively. After five consecutive cycles, the degradation rate still reached 72.35%, which has high photocatalytic stability. Combined with energy band structure analysis, active substance capture experiments and modeling with density functional theory calculations confirm the photocatalytic mechanism of Z-scheme heterostructure. This project proposes a promising and feasible method for the preparation of Z-scheme heterostructured photocatalysts.

BiOBr/MXene/gC3N4 Z-scheme heterostructure photocatalysts mediated by oxygen vacancies and MXene quantum dots for tetracycline degradation: Process, mechanism and toxicity analysis

The rapid recombination rate of photogenerated charges make the rational design of high-performance stable photocatalysts challenging. Herein, the features of heterojunctions, oxygen vacancies (OVs), and MXene quantum dots (MQDs) were simultaneously collected in CBM (gC3N4/BiOBr/MXene) using a simple solvothermal method for the first time. OVs promoted the chemisorption of O2, MQDs not only accelerated electron transport but also promoted a photogenerated charge to selectively generate singlet oxygen, 99% of the tetracycline hydrochloride (TC-HCl) was degraded by CBM within 30 min under visible light irradiation. Thirteen intermediates and possible photocatalytic degradation pathways were proposed. It was discovered that CBM is nontoxic to the environment but can swiftly produce an excellent antibacterial effect when exposed to visible light irradiation. This research provides fresh insights into the effective removal of organic pollutants from water by combining cutting-edge defect engineering and quantum dot doping technology in photocatalytic heterojunctions.

Preparation and catalytic properties of ZnO/ Na0.5Bi0.5TiO3 composites

ZnO/Na0.5Bi0.5TiO3 composites were prepared by chemical hydrothermal deposition and hydrothermal method and the effects of ZnO adding on the properties of Na0.5Bi0.5TiO3 were investigated. The results show that the ZnO/Na0.5Bi0.5TiO3 composite with 5% ZnO content has the best photocatalytic performance and good cycling stability. Under simulated sunlight irradiation, the degradation rate for MB (10 mg/L) by ZnO/Na0.5Bi0.5TiO3 composites reached 100% within 20 minutes, and the reaction rate constant was 0.07427min−1, which were 27.51 and 6.00 times higher than those of Na0.5Bi0.5TiO3 (NBT, 0.0027 min−1) and ZnO (0.01237min−1), respectively. The incorporation of ZnO on the Na0.5Bi0.5TiO3 can form Z-scheme heterostructure ZnO/Na0.5Bi0.5TiO3 and increase the specific surface area, inhibiting the recombination of electron and hole and improving separation and transfer carriers efficiency. ZnO/Na0.5Bi0.5TiO3 composites have potential applications in high-efficiency and high-activity photocatalysts to degrade organic pollutants.

0D/3D CNQDs/CuFe2O4/Cu0 heterostructures as broad spectrum photocatalyst for efficient 5-fluorouracil degradation: Structural evolution and relay oxidation process

Undesirable solar energy absorption, poor charge transfer efficiency, and sluggish metallic ions redox cycle are three pressing problems, restricting the application of photocatalysis and peroxymonosulfate (PMS) techniques. Herein, an interface engineering of g-C3N4 quantum dots anchoring on the CuFe2O4/Cu0 hollow microspheres (CNQDs@CFO) was developed to construct a novel 0D/3D broad-spectrum-response photocatalyst. In the relaying PMS-photocatalysis process, 30 μM 5-fluorouracil (5-FLU, 50 mL) was degraded by 99.4 % in 60 min with 0.2 g L−1 1.0CNQDs@C1F1O and 0.3 mM PMS. The reusability test showed that 1.0CNQDs@C1F1O maintained superior performance with a 5-FLU removal of 92.6 % after the fifth run. Meanwhile, this newly-designed material can be applied in a large temperature and pH range, and even actual water bodies with strong environmental adaptability. Theoretic and experimental analysis demonstrated that the CNQDs and Cu0 sites on CNQDs@CFO promoted the earlier PMS activation, and then dual Z-scheme heterostructures (CNQDs/CuFe2O4/CuO) was established, boosting the follow-up photocatalytic activity.