Accelerated Charge Separation Research Articles

Nuclear Quantum Effects Accelerate Charge Separation and Recombination in g-C3N4/TiO2 Heterojunctions.

We combined ring-polymer molecular dynamics (MD) and ab initio MD with nonadiabatic MD to study the effects of nuclear quantum effects (NQEs) on interlayer electron transfer and electron-hole recombination at the g-C3N4/TiO2 interface. Our simulations indicate that NQEs significantly affect electron transfer and electron-hole recombination dynamics, accelerating both processes. NQEs deform the g-C3N4 layer and expedite the movement of carbon and nitrogen atoms, thus, enhancing charge delocalization and interlayer coupling. This improved overlap between electronic state wave functions enhances nonadiabatic couplings, facilitating electron transfer and recombination. In addition to the enhanced nonadiabatic couplings accelerating electron transfer, the presence of NQEs narrows the energy gap and delays decoherence by mitigating overall fluctuations, because of restricted TiO2 movements overwhelming enhanced g-C3N4 fluctuations, thereby making the recombination faster. This work provides valuable insights into NQEs in light-element systems and contributes to guiding the development of highly efficient photocatalysts.

In-situ construction of homogeneous Bi clusters by β-particle: MoS2/BiFeO3-x@POPs-β activate oxalate to photocatalytic oxidate hazardous oxygenated salts

The construction of heterojunction photocatalysts containing metal clusters to reduce the toxicity of metal oxides is essential for solving water pollution problems. In this study, heterostructures of MoS2/BiFeO3-x@POPs (MBFO@POPs) were successfully prepared. After irradiation, the samples showed in-situ growth of around 10 nm Bi clusters on rod MoS2 due to the domain-limiting effect of POPs. Bi clusters with a sub-nanometer scale and DFT calculations have proved that the existence of Bi clusters accelerated charge separation in the materials. Moreover, electrons transfer from Bi to MoS2 to BiFeO3-x along the heterogeneous interface. Besides, Ov (Oxygen vacancy) and Bi clusters also increased the number of active sites, leading to a significant improvement in the photocatalytic performance of the material. In this paper, a series of photocatalytic experiments were performed, employing As(III) and Sb(III) as simulated pollutants. The results revealed that the oxidation conversion of 10 mg∙L−1 As(III) and Sb(III) reached 84.7 % and 78.7 %, respectively, when oxalate was added at 0.2 mM. The results of EPR and bursting experiments showed that ·O2– and ·OH are the primary active substances in the photoreaction process. This research presents an improved solution for removing hazardous oxygenated salts from the water via the utilization of bismuth-iron-based photocatalysts and oxalates.

Boosting H2O2 photosynthesis by accumulating photo-electrons on carbonyl active site of polyimide covalent organic frameworks

The low trapping efficiency of photogenerated electrons by the targeted reduction site seriously restricts the kinetics of H2O2 photosynthesis via two-electron oxygen reduction reaction. Here, two polyimide covalent organic frameworks (PT-COF and PB-COF) possessing carbonyl groups with different electron-trapping capacity were elaborately designed. PB-COF with electron-rich carbonyl site presented 4.22 times improvement in H2O2 formation rate up to 2044 μmol g−1 h−1, and exhibited outstanding photostability after 120 h continuous opearting. Meanwhile, solar to-chemical energy efficiency was 0.68%, representing one of advanced polymer based photocatalysts. We demonstrated electronic structure of the carbonyl active center was modulated by tuning electron attraction capability of the donor unit via increased the built-in electric field to accelerate charge separation and directional transfer. The electron-rich carbonyl site is identified to boosted H2O2 photosynthesis activity via reducing the *OOH binding energy. Our work offers a tailoring electron density of pre-designable active site strategy for enhanced solar-to-chemical energy conversion.

Anatase TiO2/Defective UiO-66 porous octahedral S-scheme heterojunctions toward optimized photocatalytic performance

Photocatalysis is an alternative for antibiotics removal from wastewater for the sustainable development of human society. However, applying photocatalysts for antibiotics (e.g., tetracycline) degradation under practical conditions is highly restricted by the low reaction efficiency due to the prompt charge recombination. Constructing porous heterojunctions is an efficient way to regulate the electron transfer path and accelerate charge migration efficiency. Herein, TiO2/defective UiO-66 porous octahedral S-scheme heterojunctions are successfully fabricated through an in-situ growth strategy. The strong interaction and charge migration behavior between TiO2 and defective UiO-66 have been studied using X-ray photoelectron spectroscopy and electron paramagnetic resonance measurements. The photocatalytic removal efficiency of tetracycline is notably improved by forming TiO2/defective UiO-66 porous heterojunctions. The promoted photocatalytic performance can be ascribed to the strong interaction between TiO2 and defective UiO-66, and the accelerated charge separation and transfer efficiency due to the formation of S-scheme heterojunctions, thus generating abundant reactive oxygen species, including O2− and OH. The optimized 38-TiO2/UiO-66-300 can eliminate 97.9 % of tetracycline in 60 min with a reaction constant rate of 0.0425 min−1, which is approximately 4 and 10 times that of pristine TiO2 and UiO-66-300, respectively. This work provides an alternate strategy for preparing highly active heterojunction photocatalysts for environmental applications.

In-situ Ag SPR assisted S-scheme ZnO-CdS multi-layer core-shell heterojunction for enhanced photocatalytic degradation: Energy band engineering and reactive dynamics

Constructing an efficient photocatalyst to accelerate charge separation with strong redox capacity is in pursuit all the way. Herein, a novel heterojunction was achieved for efficient organic degradation, which took advantages of S-scheme mechanism, metal surface plasma resonance (SPR) and unique morphology. The multi-layer core-shell structure can be regulated by aging time with template-free, and Ag nanoparticles were modified on the heterojunction by photochemical deposition in situ to facilitate electron transport and improve stability. S-scheme and SPR endues the heterojunction with broad light absorption, increased light utilization, efficient carrier separation, and strong redox capacity. An examination of reactive dynamics revealed that superoxide radicals and hydroxyl radicals are crucial for oxidative degradation. Introducing oxygen during the reaction process has been found to enhance the efficiency by 7 %. This article furnishes novel insights into a coordination of energy band engineering, structure regulation, as well as reaction process adjustment for facilitating photo-degradation reactions.

A Novel Perspective on Enhancing Photocatalytic Performance through the Synergistic Effect of Nd Single Atoms and Heterostructures.

There are few reports on lanthanide single atom modified catalysts, as the role of the 4f levels in photocatalysis is difficult to explain clearly. Here, the synergistic effect of 4f levels of Nd and heterostructures is studied by combining steady-state, transient, and ultrafast spectral analysis techniques with DFT theoretical calculations based on the construction of Nd single atom modified black phosphorus/g-C3N4 (BP/CN) heterojunctions. As expected, the generation rates of CO and CH4 of the optimized heterostructure are 7.44 and 6.85 times higher than those of CN, and 8.43 and 9.65 times higher than those of BP, respectively. The Nd single atoms can not only cause surface reconstruction and regulate the active sites of BP, but also accelerate charge separation and transfer, further suppressing the recombination of electron-hole pairs. The electrons can transfer from g-C3N4:Nd to BP:Nd, with a transfer time of ≈11.4ps, while the radiation recombination time of electron-hole pairs of g-C3N4 is ≈26.13 µs, indicating that the construction of heterojunctions promotes charge transfer. The 2P1/2/2G9/2/4G7/2/2H11/2/4F7/2→4I9/2 emissions from Nd3+ can also be absorbed by heterostructures, which improves the utilization of light. The energy change of the key rate measurement step CO2 *→COOH* decreases through Nd single atom modification.

Construction of Au/ZnWO4/CdS Ternary Photocatalysts with Oxygen Vacancy Modification for Efficient Photocatalytic Hydrogen Production

AbstractRational design and optimization of the photocatalyst architecture, aimed at effectively enhancing light absorption and accelerating charge separation and transfer, can lead to the accomplishment of sustainable photocatalytic hydrogen production. In this study, a ternary system of Au/ZnWO4/CdS is prepared with oxygen vacancy modification through a combination of hydrothermal, chemical precipitation, and photochemical deposition methods. The addition of CdS and Au nanoparticles significantly enhances the light absorption range of ZnWO4 (ZWO) and creates more active sites for hydrogen production. The type‐II engineered heterojunction, in combination with Au as a cocatalyst, is a viable and efficient method for enhancing the separation and transport of electron–hole pairs, thereby facilitating the effective precipitation of hydrogen through photocatalysis. 5A10ZC exhibits a hydrogen production rate of 5483.62 µmol g−1 h−1, which is 167 times higher than that of unmodified ZWO and 29 times higher than that of pure CdS. In addition, it exhibits excellent cycle stability in the hydrogen production cycle stability test. The photoelectrochemical test results show that the construction of the system improves the separation and transfer efficiency of photogenerated carriers. This study provides a new inspiration for the construction of high‐performance photocatalytic materials.

Cr dopants and S vacancies in ZnS to trigger efficient photocatalytic H2 evolution and CO2 reduction

Driven by endless solar energy, photocatalytic H2 evolution from water splitting and CO2 conversion to hydrocarbon fuels over semiconductor photocatalysts are of great potential to simultaneously settle the greenhouse effect and energy shortage. Herein, Cr-doped zinc sulfide (ZnS) with accompanying sulphur vacancies (Vs) photocatalytic materials is developed by a facile hydrothermal method. The Cr dopants centralize photoinduced holes and Vs trap electrons, forming a synergistic effect for accelerating charge separation and transfer. The reaction energy barrier for both H2 evolution and CO2 reduction has been optimized. Therefore, in the absence of a cocatalyst, the optimal catalyst (Zn0.94Cr0.06S) achieves an outstanding H2 evolution activity of 20.3 mmol g−1 h−1, which is approximately 2.9 times higher than 6.9 mmol g−1 h−1 for pristine ZnS. In addition, in the gas-solid reaction system without co-catalysts or sacrificial agents, the Zn0.94Cr0.06S exhibits a considerable CO evolution rate of 19.56 μmol g−1 h−1, about 10.1 times higher than ZnS (1.94 μmol g−1 h−1). Both the performances for H2 evolution and CO2 reduction of Zn0.94Cr0.06S outperform most of the previously reported photocatalysts. Particularly, the Zn0.94Cr0.06S possesses superior stability, the photoactivity of which exhibits no noticeable deactivation after six cycles’ reactions. This work may shed light on the rational design and fabrication of highly efficient materials via combining individual element doping and defect engineering.

Oxygen vacancies-tuned BiOBr nanosheets for accelerating CO2 and Cr(VI) photoreduction

Unsatisfactory charge separation ability and insufficient active sites are the main factors leading to low efficiency for photocatalytic CO2 conversion and Cr(VI) reduction. Constructing surface defects to accelerate charge separation is an effective strategy for promoting photocatalytic process. Herein, the oxygen vacancies modulated BiOBr nanosheets were constructed by NaBH4 solution treatment. Density functional theory calculation results found that the formed oxygen vacancies would increase the electron density around Bi atoms near the oxygen vacancies, and inhibiting recombination of the photoinduced carriers. Besides, abundant oxygen vacancies can effectively enhance the adsorption of CO2 molecules. Therefore, the BiOBr with rich oxygen vacancies (BiOBr-ROV) shows higher evolution rates for CO (15.66 μmol g−1) and CH4 (0.22 μmol g−1) under irradiation of 300 W Xe lamp for 4 h compared with pristine BiOBr nanosheets (BiOBr) and BiOBr with deficient oxygen vacancies (BiOBr-DOV). The intermediate products in the CO2 reduction process have been detected by in-situ Fourier-transform infrared spectroscopy. Besides, the photodegradation activity of Cr(VI) over BiOBr-ROV is 98.65% under 80 min of irradiation, which is higher than that of BiOBr (78.01%) and BiOBr-DOV (53.67%). The work provides a new possibility to construct photocatalysts with high-performance for solar energy conversion.

Coordination engineering of the interfacial chemical bond and sulfur vacancies modulated S‐scheme charge transfer for efficient photocatalytic CO2 reduction

Surface charge localization and poor carrier separation efficiency limited the of photocatalytic CO2 reduction (PCR) activity. Creating heterojunctions between the interfacial layers was an important strategy used to enhance catalytic activity. Here, a core-shell structure S-scheme catalyst was constructed by growing of Bi2WO6 (BWO) nanospheres on the surface of Zn0.5Cd0.5S(VS-ZCS) nanospheres with abundant sulfur defect, and which was coordinated by the interface bonding and the sulfur vacancies (VS) for efficient PCR. Meanwhile, the surface potential was 91 mV, indicating the creation of strong interface electric field (IEF). As part of the strong synergy of the Bi-S bond, IEF and VS, the improved photocatalyst exhibited high CO evolution rate of 86.16 μmol⋅g−1, which was about 9.23 fold of the pristine VS-ZCS. This was attributed to production of *COOH intermediates on the VS-ZCS/BWO surface that had been proved to be crucial for PCR generation CO. Besides, electrons quickly migrated through the formed Bi-S bonds to the catalytic sites, accelerating charge separation. The use of VS as electron traps was beneficial for regulating the localization of photogenerated charges on the surface of S-scheme heterostructure. The Bi-S bonds and VS modulated S‐scheme charge transfer for efficient photocatalytic CO2 reduction provides new insights into photocatalytic CO2 reduction.

Tailored Exfoliation of Polymeric Carbon Nitride for Photocatalytic H2O2 Production and CH4 Valorization Mediated by O2 Activation.

The exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation-decomposition (NID) strategy that is effective in peeling off BCN into few-layer C3N4 (fl-CN) with tailored thickness down to bi-layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl-CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl-CN-530 catalyst is 952 μmol g-1 h-1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on-site formed H2O2 and active oxygen species to generate value-added C1 oxygenates with high selectivity of 99.2 % and record-high production rate of 1893 μmol g-1 h-1 among the metal-free C3N4-based photocatalysts.

Tailored Exfoliation of Polymeric Carbon Nitride for Photocatalytic H2O2 Production and CH4 Valorization Mediated by O2 Activation

AbstractThe exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation‐decomposition (NID) strategy that is effective in peeling off BCN into few‐layer C3N4 (fl‐CN) with tailored thickness down to bi‐layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl‐CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl‐CN‐530 catalyst is 952 μmol g−1 h−1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on‐site formed H2O2 and active oxygen species to generate value‐added C1 oxygenates with high selectivity of 99.2 % and record‐high production rate of 1893 μmol g−1 h−1 among the metal‐free C3N4‐based photocatalysts.

Accelerating Charge Separation and CO2 Photoreduction in Aqueous Phase under Visible Light with Ru Nanoparticles Loaded on Ga-Doped NiTiO3 in a Batch Photoreactor.

Titanate perovskite (ATiO3) semiconductors show prospects of being active photocatalysts in the conversion of CO2 to chemical fuels such as methanol (CH3OH) in the aqueous phase. Some of the challenges in using ATiO3 are limited light-harvesting capability, rapid bulk charge recombination, and the low density of catalytic sites participating in CO2 reduction. To address these challenges, Ga-doped NiTiO3 (GNTO) photocatalysts in which Ga ions substitute for Ti ions in the crystal lattice to form electron trap states and oxygen vacancies have been synthesized in this work. The synthesized GNTO was then loaded with Ru nanoparticles to accelerate charge separation and enable excellent CO2 photoreduction activity under visible light. CO2 photoreduction was conducted in a batch photoreactor charged with a 0.1 M NaHCO3 aqueous solution at room temperature and a 3.5 bar pressure using a 1.0 wt % Ru-GNTO photocatalyst to yield methanol at a rate of 84.45 μmol g-1 h-1. A small amount of methane was produced as a side product at 21.35 μmol g-1 h-1, which is also a fuel molecule. We attribute this high catalytic activity toward CO2 photoreduction to a synergistic combination of our novel heterostructured 1.0 wt % Ru-GNTO photocatalyst and the implementation of a pressurized photoreactor. This work demonstrates an effective strategy for metal doping with active nanospecies functionality to improve the performance of ATiO3 photocatalysts in valorizing CO2 to solar fuels.

Enhanced photocatalytic activity of BiOCl/BiOBr/SnS2 heterojunction using a superfine SnS2 and double S-scheme

Photocatalysis is a green approach to solving energy and environmental problems, and researchers are still pursuing high-performance photocatalysts. Although BiOX (X = Cl or Br) has a suitable bandgap and good stability, its photoresponse is mostly concentrated in the UV region. Conversely, SnS2 has a wide photoresponse range but exhibits perceptible photocorrosion and poor stability. To exploit the advantages of both BiOX and SnS2, this study hydrothermally synthesized and introduced superfine SnS2 (∼30 nm in size) into a BiOCl/BiOBr binary system to fabricate BiOCl/BiOBr/SnS2 composites. Subsequently, the degradation performance of these composites in a Rhodamine B solution under visible light was investigated. Results show that the BiOCl/BiOBr/SnS2 heterojunctions were successfully prepared and the composites exhibited the best photocatalytic performance with 6% mass fraction of SnS2 (BiOCl-to-BiOBr mol ratio = 1:1). The formation of a double S-schedule heterojunction between BiOCl/BiOBr and SnS2 not only accelerated charge separation and transfer but also broadened the photoresponse range and reduced photoelectron–hole recombination under full-spectrum irradiation. Loading a small narrow-bandgap photocatalyst onto a large photocatalyst provides an effective way to construct heterojunctions with excellent photocatalytic performance. The ternary photocatalyst presents a favorable photocatalytic stability, and its photodegradation rate is 4.6, 4.5 and 220.5 times that of BiOCl, BiOBr and SnS2, respectively.

Revealing the impact of different precursors and solvents for supramolecular complex formation and in-situ C-doping in g-C3N4 with enhanced photocatalytic H2O2 production

The reinforced light-harvesting capability suppresses photocarrier recombination and increases the specific surface area, representing the possibility of excellent photocatalytic performance for graphitic carbon nitride (CN) photocatalysts. Herein, the remarkable photocatalytic properties of porous carbon-doped g-C3N4 (CCN) were enhanced through the incorporation of a supramolecular complex, M-CA-U (melamine-cyanuric acid-urea), in DMSO as the carbon dopant source. Through the diverse characterization methods, the successful formation of the supramolecular g-C3N4 using varying polarity of solvent was verified, achieved through a simple hydrothermal/solvothermal process. The CCN-MCAU-DMSO photocatalyst achieved the maximum photocatalytic H2O2 production rate, 1.3-fold higher than other prepared samples. The outstanding performances of CCN-MCAU-DMSO were probably attributed to the extended specific surface area, robust visible light response, adjusted electronic band structure, accelerated charge separation, and limited charge recombination. The photocurrent response and photoluminescence spectroscopy analysis confirmed excellent charge carriers and separation. Overall, this work provided a new idea to design and construct high-efficiency porous supramolecular assembly of CCN photocatalysts for photocatalytic studies.

Oxygen vacancies generation in CeO2 via Y/Nd co-doping with accelerated charge separation by decorating on rGO sheets for sunlight-driven photodegradation of hazardous dyes

In the present study, Y/Nd co-doped CeO2 (CeYNdO2) nanoparticles and rGO-supported CeYNdO2/rGO nanocomposite were synthesized via sol-gel route. The obtained nanocomposite has outstanding redox features, highlighting a large surface area, excellent light-capturing response, abundant oxygen vacancies, remarkable photodestruction performance, and promising stability compared with CeYNdO2 nanoparticles. Especially, using the optimal condition, the photodestruction efficiencies of MB, SO, and EY reached up to 99.2 %, 71.8 %, and 99.7 % only in 60 min of irradiation for CeYNdO2/rGO nanocomposite, respectively. The several influencing parameters including catalyst dose, dye amount, pH variation, and main reactive radicals were tested to evaluate the CeYNdO2/rGO nanocomposite performance. The stability of the CeYNdO2/rGO nanocomposite was also tested for the repetitive 6th cycles. Moreover, the probable photodestruction pathways, and reasonably boosted performance were thoroughly investigated given in Scheme- 1. The obtained results highlight that the Y/Nd doping and rGO synergy is promising for environmental remediation, and propose a reasonable low-cost strategy to modify the performance of CeO2-based composite materials, especially in photodestruction of toxic dyes.

Key Strategies on Cu2O Photocathodes toward Practical Photoelectrochemical Water Splitting.

Cuprous oxide (Cu2O) has been intensively in the limelight as a promising photocathode material for photoelectrochemical (PEC) water splitting. The state-of-the-art Cu2O photocathode consists of a back contact layer for transporting the holes, an overlayer for accelerating charge separation, a protection layer for prohibiting the photocorrosion, and a hydrogen evolution reaction (HER) catalyst for reducing the overpotential of HER, as well as a Cu2O layer for absorbing sunlight. In this review, the fundamentals and recent research progress on these components of efficient and durable Cu2O photocathodes are analyzed in detail. Furthermore, key strategies on the development of Cu2O photocathodes for the practical PEC water-splitting system are suggested. It provides the specific guidelines on the future research direction for the practical application of a PEC water-splitting system based on Cu2O photocathodes.

Super-strong Zn and S atomic terminals in an organic/inorganic hybrid S-scheme polyimide based heterojunction for efficient photocatalytic treatment of mixed pollutant wastewater

Integrated oxidation and reduction reactions in the field of wastewater treatment with mixed high concentrations of sewage achieved by photocatalysis are highly desirable but still challenging. The construction of the S-scheme heterojunction system is expected to be a promising strategy to provide carriers with strong redox ability for oxidation of oxytetracycline hydrochloride (OTC) with simultaneous reduction of hexavalent chromium (Cr(VI)). Reduced graphene oxide (rGO) and ZnIn2S4 (ZIS) were successively assembled on perylene diimide polymer (PDIP) nanorods to form the S-scheme ZIS/rGO/PDIP heterojunction. The construction of organic–inorganic systems achieves wide light absorption, enhanced exciton dissociation and accelerated charge separation. A non-radiation-quenched electron transport path is formed in the ZIS/rGO/PDIP system from the conduction band of PDIP through rGO to the valence band of ZIS. The electronic energy state of the S-scheme ZIS/rGO/PDIP heterojunction was changed, and the Zn and S atomic terminals can realize strong adsorption of OTC and Cr(VI).

Piezoelectric polarization accelerated charge separation in Zinc stannate based Schottky barrier for high-efficiency hydrogen evolution

Piezoelectric polarization can effectively improve the separation and transfer of the carriers in photocatalyst. Herein, a dimension-matched piezo-photocatalyst was designed based on plate-like orthorhombic perovskite Zinc stannate (ZnSnO3)@reduced graphene oxide (rGO), which verified the prominent hydrogen (H2) evolution performance. Driven by the mechanical vibration induced piezoelectric field, the limitation of photocatalytic H2 evolution on the proper band edge position had been breached. The band of ZnSnO3 could be tilted more negative than H2O/H2 redox potential under the piezoelectric field, making it possible to achieve H2 evolution which was originally unsatisfactory. Moreover, on the basis of piezoelectric field, the Schottky barriers established in the catalyst further accelerated the electron separation. The electron paramagnetic resonance results demonstrated that the strongest ·O2− and ·OH radical intensities could only be observed when under the synergistic of light and ultrasonic. The effect of contents, size, surface chemistry of rGO and the ultrasonic power on piezo-photocatalytic performance were also optimized. Satisfactory, the ZnSnO3@rGO exhibited superior piezo-photocatalytic H2 evolution (5.66 mmol g−1), which was four times more than that of ZnSnO3 (1.37 mmol g−1). This work sheds light on the essentially synergistic effect of the mechanical and luminous energy in H2 evolution through piezo-phototronic process.

Dual function of magnetic field in enhancing antibiotic wastewater treatment by an integrated photocatalysis and fluidized bed biofilm reactor (FBBR)

The integrated photocatalysis and fluidized bed biofilm reactor (FBBR) is an attractive wastewater treatment technique for managing wastewater containing antibiotics. However, the fast recombination of photoinduced charge and low microbial activity limit the degradation and mineralization efficiency for antibiotics. To address this, we attempt to introduce magnetic field (MF) to the integrated system with B-doped Bi3O4Cl as the photocatalysts to effectively improve removal and mineralization of ciprofloxacin (CIP). As a consequence, the degradation rate reaches 96% after 40 d in integrated system with MF. The biofilm inside the integrated system with MF carrier can mineralize the photocatalytic products, thereby increasing the total organic carbon (TOC) degradation rate by more than 32%. The electrochemical experiment indicates the Lorentz force generated by MF can accelerate charge separation, increasing the electron concentration. Simultaneously, the increased amounts of electrons lead to the generation of more ·OH and ·O2−. MF addition also results in increased biomass, increased biological respiratory activity, microbial community evolution and accelerated microbial metabolism, enabling more members to biodegrade photocatalytic intermediates. Therefore, applied MF is an efficient method to enhance CIP degradation and mineralization by the integrated system.