Accelerated Charge Separation Research Articles

Construction of hollow core-shell ZnO@Co3O4 p-n heterojunction for CO2 cycloaddition under visible light irradiation

In comparison to a single semiconductor, constructing p-n heterojunctions represents an efficient strategy for enhancing photocatalytic activity because of their advantages in accelerating charge separation and promoting photoabsorption. Herein, we propose a novel metal–organic framework (MOF)-assisted and controlled pyrolysis strategy for constructing a hollow core-shell p-n heterojunction photocatalyst ZnO@Co3O4. It is worth noting that the hollow core-shell heterojunction not only provides abundant active sites but also significantly facilitates the separation of photogenerated charge carriers and accelerates electron transfer. Benefiting from the above advantages, the optimized ZnO@Co3O4(400,2), obtained by pyrolysis at 400 ℃ for 2h using Zn-MOF@Co-MOF as a precursor, exhibits high activity for the cycloaddition of CO2 and epichlorohydrin, resulting in a 94% yield of 4-(chloromethyl)-1, 3-dioxolan-2-one under 1bar CO2 pressure and visible light irradiation for 2h, which is significantly superior to those of ZnO(400,2) (5%), Co3O4(400,2) (38%), and the physically mixed counterparts (55%). This work provides insightful guidance for designing efficient photocatalysts aimed at CO2 cycloaddition, thereby achieving solar to high-value-added chemical conversion efficiencies.

Designing interfacial chemical bond by anchoring defective CeO2-x nanorods with bismuth-rich Bi4O5Br2 nanosheets: Modulated Z-scheme charge transfer for photocatalytic degradation of antibiotic

Exploring and implementing precise carrier-transfer channels in the interface of Z-scheme heterojunctions are crucial and considered significant challenges. Here, a one-dimensional/two-dimensional (1D/2D) heterostructure Z-scheme photocatalyst was constructed by in situ growing of defective CeO2-x nanorods on the surface of Bi-rich Bi4O5Br2 nanosheets, which was coordinated by the interface bonding and the dual oxygen vacancies for efficient photocatalytic degradation activity of tetracycline. Both experimental results and theoretical calculations elucidated that the compact 1D/2D structure and dual oxygen vacancies induced interfacial Br-O-Ce bond to act as charge bridges providing direct ohmic contacts, thus realizing a Z-scheme charge transfer mechanism that promoted effective charge separation and maximized the redox capacity. Meanwhile, the surface potential was 31.92 mV, indicating the creation of a strong interface electric field (IEF). As part of the strong synergy of the Br-O-Ce bond, IEF and dual oxygen vacancies, the optimal defective CeO2-x@Bi-rich Bi4O5Br2 exhibited superior photocatalytic activity and 85.40 % tetracycline (TC) was decomposed within 40 min, which was 65.7 and 2.1 times higher than CeO2-x and Bi4O5Br2, respectively. Besides, electrons quickly migrated through the formed Br-O-Ce bonds to the catalytic sites, accelerating charge separation. Our findings provide new insights to develop the interfacial chemical bond and dual oxygen vacancies modulated Z‐scheme charge transfer for efficient photocatalysis.

Accelerating charge separation in p-n heterojunction photocathode for photoelectrochemical oxygen reduction and evolution in photo-enhanced zinc-air battery

For the first time, we constructed a band-matched ZnO/NiO staggered p-n heterojunction photoelectrochemical (PEC) catalyst with superior charge separation and transfer efficiency to optimize the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics demands of a photo-enhanced zinc-air battery (PZAB). The ingenious design of heterojunction architecture effectively stimulates an internal self-built electric field (BEF), thus accelerating charge separation and migration during PEC catalysis. Upon illumination, the photocathode not only endows a promoted PEC catalytic competence to drive ORR and OER, but also reduces the charge–discharge voltage gap of PZAB. Density functional theory (DFT) calculations further disentangled the PEC catalysis activity origins by substantiating the strongly decreased Gibbs free energy potently for generating the essential intermediates *OH and *OOH during ORR and OER, respectively, and visualized the charge densities in photocathode to illustrate the authentic separation of photogenerated carriers. Remarkably, our work experimentally and theoretically sheds lights on engineering innovative and efficient bifunctional PEC catalysts to drive PZABs with photo-enhancement.

Nd3+ induces three-dimensional hierarchical rosette-shaped Bi3O4Br to generate abundant oxygen vacancies for enhanced photocatalytic activity

Three-dimensional hierarchical rosette-shaped Bi3O4Br has been successfully prepared by a one-step hydrothermal method for the first time, in which the doping of Nd3+ into the matrix of Bi3O4Br induces abundant oxygen vacancies and triggers energy-band hybridization to produce new dopant levels, which can efficiently receive photo-excited electrons and inhibit the complexation of photogenerated carriers. Impressively, the doped energy levels act as “springboards” for photogenerated electron jumps, exacerbating the inhomogeneity of charge distribution and accelerating charge separation. In addition, the fine-tuning of Nd3+ improves the band structure and photocatalytic performance of Nd/Bi3O4Br. Notably, the unique 3D rosette-like Bi3O4Br could enhance the adsorption capacity of the catalyst and provide more opportunities for the introduction of Nd3+ to induce the generation of abundant oxygen vacancies. Both experimental and density functional theory (DFT) results reveal the synergistic effect of energy band hybridization and oxygen vacancies. In addition, comparative experiments showed that Nd/Bi3O4Br enhanced the maximum removal efficiency of heavy metal mercury by 29.66 % relative to Bi3O4Br under visible light. The present work reveals the reaction mechanism of photocatalytic oxidation for mercury removal, which provides a new direction for realizing energy conversion and environmental purification in the future.

Efficiency and mechanistic insights of photocatalytic degradation and sterilization utilizing g-C3N4/WO3-x Z-scheme heterojunction under full-spectrum light

Designing highly efficient full-spectrum responsive Z-scheme heterojunction for wastewater decontamination and disinfection is urgently essential. Herein, a novel Z-scheme g-C3N4/WO3-x heterojunction was successfully synthesized by a facile wet impregnation method for the highly efficient photocatalytic degradation and sterilization. Benefiting from the accelerated charge separation, broadened light absorption to near infrared region, and appropriate band energy, optimized g-C3N4/WO3-x heterojunction exhibited photocatalytic degradation of 86.3 % and 97.4 % tetracycline in 2 h under visible light and full-spectrum light, respectively. Meanwhile, 6.5-log of Escherichia coli strains could also be inactivated by optimized g-C3N4/WO3-x heterojunction within 45 min and 15 min under visible light and full-spectrum light, respectively. Impressively, it also exhibited desirable anti-interference ability and satisfying photocatalytic degradation capacity with various key experimental parameters. The plausible degradation pathways of TC and the main active species involved in the photocatalysis were investigated based on liquid chromatography-mass spectrometer (LC-MS) and electron paramagnetic resonance (EPR) analysis. Mineralization process of TC was further confirmed by three-dimensional fluorescence spectra (3D EMMs). Besides, Toxicity Estimation Software Tool (T.E.S.T.) and Ecological Structure-Activity Relationships (ECOSAR) program were applied to predict the noxiousness of TC and its potential intermediates. The results suggested that the excitotoxicity of intermediates generally decreased relative to the pristine TC. Finally, we propose a plausible enhancement mechanism of photocatalytic degradation and sterilization. This work sheds a new light on the design of novel full-spectrum responsive Z-scheme heterojunction for environmental remediation.

Interface engineering of AgI/(P, K)-g-C3N4 novel S-scheme heterostructures as a highly efficient photocatalyst for RhB degradation

In this study, we developed an in-situ deposition method to load small-sized AgI nanoparticles as an oxidative photocatalyst (OP) onto phosphorus (P) and potassium (K) co-doped two-dimensional porous g-C3N4 (PK-CN-N) as a reductive photocatalyst (RP), forming an S-scheme heterojunction photocatalyst AgI/PK-CN-N. PK-CN-N achieved morphology control and element doping, leading to surface functionalization and heterostructure formation for the AgI/PK-CN-N photocatalyst. Notably, the 50AgI/PK-CN-N composite demonstrated an approximately 95 % removal efficiency for RhB within 30 minutes, 17.6 times higher than pure g-C3N4, surpassing most reported g-C3N4-based photocatalysts. The enhanced photocatalytic efficiency is attributed to the surface modification strategy and heterostructure formation of g-C3N4, which broadens the visible light response range, increases the number of active sites, improves the separation of photogenerated electron-hole pairs, and enhances REDOX capabilities. The band structure of the composite was elucidated through Mott-Schottky analysis and UV–vis DRS. The formation of the AgI/PK-CN-N S-scheme heterojunction and its charge transfer mechanism was confirmed through XPS, band structure analysis, KPFM, and EPR spectroscopy. Experimental data confirmed the presence of a strong and effective interface electric field between the two semiconductors, leading to band bending and accelerated charge separation. Additionally, the introduction of small-sized AgI semiconductors enhanced the exposure of the coupling interface, further improving catalytic performance. The reusability and lifespan of the catalyst were also analyzed, showing that after four cycles, the photocatalytic activity remained above 92 %.

Construction S-scheme Bi4O5Br2/BiOI composite for accelerated charge separation and enhanced photocatalytic degradation and antibacterial performance

Photocatalytic technology is an effective solution to environmental pollution problems. The development of efficient photocatalysts is of great practical significance for environmental remediation. In this study, Bi4O5Br2/BiOI S-scheme heterojunction was successfully prepared by solvothermal and facile room-temperature deposition methods. The optimum sample 30 % Bi4O5Br2/BiOI (BrI-30) could degrade 90.5 % methyl orange (MO) in 60 min and 71.6 % tetracycline (TC) in 90 min under LED light irradiation, and it could completely inactivate Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in 30 min. Bi4O5Br2/BiOI composites exhibited efficient degradation and antimicrobial activities, which were principally ascribed to the formation of the heterojunction interface between Bi4O5Br2 and BiOI facilitating the migration of photo-generated carriers. The effects of different factors on the photo-degradation properties were systematically investigated. In addition, mass spectrometry (MS) has been accustomed to detecting the intermediates formed when TC degraded and possible pathways for TC degradation were proposed. Eventually, based on energy-band analysis, the mechanism of removing pollutants and inactivating bacteria in Bi4O5Br2/BiOI composites was proposed. This study provides a novel solution for treating organic pollutants and bacteria in water bodies, which has practical applications in environmental remediation.

Facilitating Charge Separation of Donor–Acceptor Conjugated Microporous Polymers via Position Isomerism Strategy for Efficient CO2 Photoconversion

Photoreduction of CO2 into the chemical feedstocks of fuels provides a green way to help solve both the energy crisis and carbon emission issues. Nevertheless, undesirable charge separation and migration, as well as rapid reverse charge recombination results in the unsatisfactory photocatalytic activity of most conjugated microporous polymers (CMPs). Herein, a pair of donor–acceptor (D-A) CMPs for CO2 photoconversion was developed through position isomerism by altering linkage sites. The results show that Py-D27F with 2,7-site linkage exhibits a completely conjugated structure and a large molecular dipole moment, thus significantly accelerating charge separation and transfer. As a result, Py-D27F achieves a higher yield of 320.9 μmol g−1 h−1 for CO2-to-CO photoreduction (without the addition of any photosensitizers and precious metals), which is about three-fold greater than that of Py-D36F (3,6-site linkage). This study provides a valuable idea for exploring outstanding CMP photocatalysts for the efficient processing of photocatalysis.

Interface coupling to improve O2 adsorption and accelerate charge separation for boosting photocatalytic performance of ZnO/ZnIn2S4 composite in H2O2 production and environmental remediation

The key to heterogeneous photo-Fenton technology lies in the efficient generation of hydrogen peroxide (H2O2). Herein, a newly-designed ZnO/ZnIn2S4 composite with heterostructure is synthesized. Benefiting from the formation of built-in electric field, the recombination of photoinduced electrons and holes is suppressed and interfacial charge transfer resistance is reduced. Importantly, the embedding of ZnO in ZnIn2S4 can improve the hydrophobicity and create microscopic three-phase interface, thereby boosting the capture capability for O2 and providing the convenience for the occurrence of O2 reduction reaction. More interestingly, the existence of ZnIn2S4 in the ZnO/ZnIn2S4 composite can reduce the Gibbs free energy (ΔG) of key intermediate (OOH*) formation, which will accelerate the generation of H2O2. As a result, the ZnO/ZnIn2S4 composite displays excellent performance in photocatalytic H2O2 production, and the highest yield was about 897.6 μmol/g/h within 60 min under visible light irradiation. The transfer of photoinduced carriers follows the S-scheme type mechanism. The photogenerated holes can be captured by drug residues (i.e., diclofenac sodium) to accelerate H2O2 production, while generated H2O2 can combine with Fe2+ to construct photo-Fenton system for achieving the advanced degradation of diclofenac sodium, which was mainly related to the formation of OH•. Furthermore, generated H2O2 can be applied for performing the inactivation of pathogenic bacteria. In short, current work will provide a valuable reference for future research.

Construction of g-C3N4@Bi-MOF@BiOCl double Z-type heterojunctions for photodegradation of antibiotics under visible light irradiation: Mechanism, pathway, and toxicity assessment

In this study, flower-like microspheres dispersed double Z-type heterojunction g-C3N4@Bi-MOF@BiOCl photocatalysts were prepared using Bi-MOF as the structural template. The photocatalyst showed good degradation ability for both tetracycline antibiotics under simulated sunlight irradiation, as well as stable recyclability and total organic carbon mineralization (TOC). This excellent photocatalytic activity was mainly attributed to the formation of double Z-type heterojunctions that accelerated charge separation and transfer and drove stronger redox capacity. In addition, the effects of conditions such as catalyst dosage, initial concentration of tetracycline hydrochloride (TC) and initial pH (3–11) value of the solution on the photocatalytic reaction were investigated. The results of free radical trapping experiments and ESR analyses indicated that O2−, h+ and OH were the active free radicals that could not be neglected for the degradation of tetracycline hydrochloride (TC), and a possible degradation mechanism was further proposed. Finally, the possible pathways for degradation of the intermediates were rationally deduced by gas chromatography (GC–MS) and evaluated by ecotoxicity analysis based on the utilization rate (T.E.S.T.) of the intermediates produced. This study provides an effective idea for the rational design and synthesis of highly efficient dual Z-type photocatalysts for antibiotic contamination in water-polluted environments.

Boosting the Activation of Molecular Oxygen and the Degradation of Rhodamine B in Polar-Functional-Group-Modified g-C3N4.

Molecular oxygen activation often suffers from high energy consumption and low efficiency. Developing eco-friendly and effective photocatalysts remains a key challenge for advancing green molecular oxygen activation. Herein, graphitic carbon nitride (g-C3N4) with abundant hydroxyl groups (HCN) was synthesized to investigate the relationship between these polar groups and molecular oxygen activation. The advantage of the hydroxyl group modification of g-C3N4 included narrower interlayer distances, a larger specific surface area and improved hydrophilicity. Various photoelectronic measurements revealed that the introduced hydroxyl groups reduced the charge transfer resistance of HCN, resulting in accelerated charge separation and migration kinetics. Therefore, the optimal HCN-90 showed the highest activity for Rhodamine B photodegradation with a reaction time of 30 min and an apparent rate constant of 0.125 min-1, surpassing most other g-C3N4 composites. This enhanced activity was attributed to the adjusted band structure achieved through polar functional group modification. The modification of polar functional groups could alter the energy band structure of photocatalysts, narrow band gap, enhance visible-light absorption, and improve photogenerated carrier separation efficiency. This work highlights the significant potential of polar functional groups in tuning the structure of g-C3N4 to enhance efficient molecular oxygen activation.

(Invited) A CNT Binding Bis(Zinc Porphyrin)Bodipy-C60 Nano Tweezer: Charge Stabilization in Supramolecular C60-Bodipy-(ZnP)2:SWCNT Hybrids

Single-wall carbon nanotubes (SWCNT) coupled with either electron donor or acceptor are promising functional structures for light energy harvesting and molecular optoelectronics applications. For building such hybrids involving SWCNTs, the p-stacking ability of large aromatic compounds is one of the commonly employed approaches.1-2 Often, the desired donor or acceptor entities are functionalized to carry one or more aromatic entities and allowed to interact with CNTs. However, due to close proximity, the role of SWCNTs in stabilizing the electron transfer product has been a challenge.3 Recently, we overcame this hurdle by employing a multi-modular approach to build donor-acceptor hybrids and successfully demonstrated charge stabilization in the presence of SWCNTs.4 In the present study, we have further improved our design by newly synthesizing a nano tweezer comprised of covalently linked BODIPY-C60 carrying two zinc porphyrin arms as shown in the figure. This compound was further allowed to interact with SWCNT(6,5) and SWCNT(7,6) to form the supramolecular C60-BODIPY-(ZnP)2:SWCNThybrids. Upon spectral, electrochemical, and computational characterization, femtosecond pump-probe spectroscopic studies were performed to establish the occurrence of photoinduced charge separation and charge stabilization. Extending the lifetime of the charge-separated states upon SWCNT binding has been successfully demonstrated in the present molecular design strategy. D’Souza, F.; Sandanayaka, A. S. D.; Ito, O. ‘SWNT-Based Supramolecular Nanoarchitectures with Photosensitizing Donor and Acceptor Molecules’ Phys. Chem. Letts. 2010, 1. 2586-2593.B. KC, G. N. Lim, and F. D’Souza, ‘Accelerated Charge Separation in Graphene Decorated Multi-Modular Tripyrene-Subphthalocyanine-Fullerene Donor-Acceptor Hybrids,’ Angew. Chem. Int. Ed. 2015, 54, 5088-5092.Barrejon, L. M. Arellano, F. D’Souza, F. Langa, ‘Bidirectional charge transfer in carbon-based hybrid nanomaterials’ Nanoscale, 2019, 11, 14978-14992.Kazemi, Y. Jang, A. Liyanage, P. A. Karr, and F. D’Souza, A Carbon Nanotube Binding Bis(pyrenylstyryl)BODIPY-C60 Nano Tweezer: Charge Stabilization through Sequential Electron Transfer, Angew. Chem. Int. Ed. 2022, 61, e202212474 (1-7). Figure 1

Reasonably construct GDY/CeO2/Mn0.2Cd0.8S double S-scheme heterojunction for improvement photocatalytic hydrogen production

Reasonably designing and optimizing the structure of photocatalysts aims to effectively enhance light absorption, accelerate charge separation and transfer, and achieve sustainable photocatalytic hydrogen production. In this study, a simple self-assembly method was used to prepare the GDY/CeO2/Mn0.2Cd0.8S ternary system. The addition of GDY and CeO2 significantly enhances the light absorption range of Mn0.2Cd0.8S, enhancing the separation and transmission of electron hole pairs and provides more active sites for hydrogen production. Moreover, an S-scheme heterojunction was constructed between the three catalysts, maximizing their oxidation–reduction ability. In addition, the built-in electric field formed between the catalysts also provides power for electron transfer, ensuring efficient and orderly reaction. This work provides ideas for the rational construction of heterojunctions, improving charge transfer, and designing high-performance catalysts to solve energy problems.

Construction of novel biochar/g-C3N4/BiOBr heterojunction with S-scheme mechanism for efficient photocatalytic degradation of tetracycline

In this work, a novel biochar/g-C3N4/BiOBr (BCN/BiOBr) S-scheme heterojunction was synthesized for the removal of tetracycline (TC) under visible light. The 0.75-BCN/BiOBr heterojunction exhibited a significantly higher degradation efficiency of TC in wastewater under visible light excitation, achieving about 86.5 % degradation in 72 minutes, which is 2.5 times higher than that of pure g-C3N4. Furthermore, the influence of factors such as pH, dosage of tetracycline and photocatalyst on TC degradation were investigated. Photochemical characterization experiments revealed that the enhanced degradation performance of the BCN/BiOBr heterojunction stemmed from the synergistic effects of adsorption and photocatalysis, providing more active sites to promote the photocatalytic reaction, and accelerating accelerate charge separation and light absorption ability. Meanwhile, the results from the active species indicated that h+, ·OH, and ·O2- play major roles in the degradation process. Additionally, the mechanism research revealed that the photogenerated carriers followed an S-scheme step transfer pathway at the interface of BiOBr and g-C3N4, and the two possible pathways for TC degradation. This provides guidance for improving wastewater treatment using biochar-modified high-efficiency S-scheme 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.

Microwave excited hyperthermy and catalysis of heterostructured Au/Cu–BTA for effective bacteria killing by accelerating charge separation

Microwave excited hyperthermy and catalysis of heterostructured Au/Cu–BTA for effective bacteria killing by accelerating charge separation

Linking the Doping-Induced Trap States to the Concentration of Surface-Reaching Photoexcited Holes in Transition-Metal-Doped TiO2 Nanoparticles.

Transition-metal doping has been demonstrated to be effective for tuning the photocatalytic activity of semiconductors. Nonetheless, the impact of doping-induced trap states on the concentration of surface-reaching photoexcited charges remains a topic of debate. In this study, through time-resolved spectroscopies and kinetic analysis, we found that the concentration of surface-reaching photoholes (Ch+(surf)) in doped TiO2 nanoparticles sensitively relies on the type of dopants and their associated trap states. Among the studied dopants (Fe, Cu, and Co), Fe doping resulted in the most significant increase in Ch+(surf), nearly double that of Co or Cu doping. Fe-doping induced more effective hole trap states, acting as the mediator for interfacial charge transfer, thus accelerating charge separation and consequently enriching Ch+(surf). This work provides valuable insight into understanding and controlling Ch+(surf) in transition-metal-doped TiO2 materials.

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.

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.