Separation Efficiency Of Carriers Research Articles

Engineered oxygen vacancies in NiCo2O4/BiOI heterostructures for enhanced photocatalytic pollutant degradation.

To address the bottleneck issue of poor carrier separation and transfer efficiency in NiCo2O4 photocatalyst, a novel 1D/2D-rod-on-rose-like NiCO2O4/BiOI nanohybrid with abundant OV's was successfully synthesized using a single-step hydrothermal method and employed to the photocatalytic degradation of Rhodamine B (RhB). The study revealed that the optimized NiCo2O4-OV/BiOI hybrid could possess superior photocatalytic degradation efficiency towards RhB degradation under visible light with a rate constant that was 3.8 and 3.03 times greater than that of BiOI and NiCo2O4-OV. Experimental findings indicated that the formation of NiCo2CO4-OV/BiOI heterojunction significantly improved the charge separation efficiency and facilitated the formation of surface OV's. These OVs enhanced photogenerated e--h+ separation and increased catalytic efficiency. Quenching experiments results confirmed that both holes and superoxide radicals are playing crucial roles in the degradation process. Thus, an oxygen vacancy and engineering NiCo2CO4-OV/BiOI heterojunction-enhanced degradation mechanism was proposed, offering insights for the integration of advanced oxidation technologies and the development of catalytic materials to enhance pollutant degradation efficiency.

TiO2-x-MoS2 heterostructure: A study of kinetic, thermodynamic, and scavenging agents’ effects in photodegradation

Numerous applications for photocatalysis exist in the energy and environmental sectors. In this study, a heterojunction system comprising oxygen vacancies-mediated TiO2 nanorods (TiO2-x) modified with MoS2 nanosheets (TiO2-x-MoS2) was prepared using the hydrothermal method. The photocatalytic activity of TiO2-x-MoS2 heterostructure is about 3 times higher than that of pure TiO2. The heterostructure significantly improved the photoinduced charge carrier separation efficiency, resulting in an increase in active species including ˙OH, O2˙−, and h+. Additionally, the Langmuir-Hinshelwood (L-H) model was employed to model kinetic and equilibrium data. The results of scavenging studies indicated that the photocatalytic process heavily relies on superoxide radicals. Additionally, the sensitivity of photocatalytic rates to temperature through kinetic studies based on Arrhenius and transition state models was investigated, which yielded an activation energy of 23.01 kJ/mol for the process. A positive activation entropy (ΔS = +0.017 kJ/mol) was obtained, along with positive ΔH and ΔG values, for the Rhodamine B photodegradation. This work underscores the critical role of oxygen vacancies and heterostructures in advancing wastewater treatment approaches.

A Cd‐Free Electron Transport Layer Simultaneously Enhances Charge Carrier Separation and Transfer in Sb2Se3 Photocathodes for Efficient Solar Hydrogen Production

AbstractEfficient photoelectrochemical (PEC) water splitting is a pivotal technique to achieve sustainable hydrogen production, driving the exploration for high‐performance photoelectrodes. Antimony selenide (Sb2Se3) semiconductor has received significant attention due to its cost‐effectiveness, eco‐friendly nature, and favorable photoelectric properties. However, traditional Sb2Se3‐based photocathodes typically employ cadmium sulfide (CdS) as an electron transport layer (ETL), which introduces toxicity and stability issues, hindering their commercial application potential. This study develops a versatile method to improve the PEC performance of Sb2Se3‐based photocathodes by incorporating Cd‐free (Zn,Sn)O ETL. Comprehensive investigations demonstrate remarkable improvement in surface and heterojunction interface properties, leading to charge carrier dynamics optimization with highly interesting carrier separation efficiency of 96.5% and transfer efficiency of 93.6%. As a result, the champion Mo/Sb2Se3/(Zn,Sn)O/TiO2/Pt photocathode delivers a notable photocurrent density (Jph) of 31.8 mA cm−2 (close to its theoretical value), and a half‐cell solar‐to‐hydrogen (HC‐STH) conversion efficiency of 4.32%. This advancement highlights a promising pathway toward large‐scale and environmentally friendly solar hydrogen production applications.

Three-Dimensional CeO2 Nanosheets/CuO Nanoflowers p-n Heterostructure Supported on Carbon Cloth as Electrochemical Sensor for Sensitive Nitrite Detection

BackgroundNitrite is widely used as a food additive, and it is of great significance to realize accurate detection of nitrite for food safety. Electrochemical technique is characterized by simple operation and portability, which enables rapid and accurate detection. The key factors affecting the nitrite detection performance are the electrocatalytic activity and interfacial electron transfer efficiency of the electrode. The electrochemical oxidation of nitrite typically requires high potentials, posing challenges for detection. Therefore, we need to develop a high-performance sensitive electrode to fulfill the need for efficient detection of nitrite. (89) ResultsWe designed a novel CeO2 nanosheets/CuO nanoflowers p-n heterostructure supported on carbon cloth, which was used to construct an electrochemical sensor for nitrite. The p-CuO NFs/n-CeO2 NSs heterojunction produced charge transfer effects and strong electronic interactions, which contributed to the increase in oxygen vacancies and enhanced the electrocatalytic activity. During electrochemical oxidation of nitrite, the p-n heterojunction achieved more efficient carrier separation, increasing the number of free electrons in the conduction band and facilitating charge transport. The electrode combines CuO nanoflowers with labyrinthine CeO2 nanosheets, significantly enhancing the electrochemically active surface area and availability of active sites, improving electron conduction efficiency and improving mass transfer efficiency. The CeO2 NSs/CuO NFs/CC showed significantly enhanced current response for the oxidation of nitrite, such as the sensitivity of 11610 μA mM−1cm−2, the linear determination range of 0.1 - 4000 μM, the LOD of 0.037 μM (S/N=3). (143) SignificanceThis work combines binary metal oxide p-n heterojunction with three-dimensional morphology optimization to design sensitive electrode with enhanced nitrite sensing performance, reduced oxidation potential and improved sensitivity. And the prepared electrode can rapidly and accurately detect nitrite residues in food samples. This work provides a high-performance nitrite electrochemical sensing platform with great practical applications. (54)

NaBiO3/g-C3N4 Z-type heterojunction modified by Ag-anchorage to enhance the photocatalytic performance

NaBiO3/Ag/g-C3N4 photocatalyst with Z-type heterostructure was developed and synthesized using photo-deposition and hydrothermal treatment methods, yielding a composite material with high REDOX ability. Because Ag in the NaBiO3/Ag/g-C3N4 composite system served as an electron capture center, the separation efficiency of photoexcited carriers was greatly increased, and the carrier lifetime was extended, as indicated by photoelectrochemical analysis. The results show that NaBiO3/Ag/g-C3N4 had much superior photocatalytic activity than monomer materials under visible light. Under visible light irradiation, the 0.1g 6% NaBiO3/Ag/g-C3N4 photocatalyst removed 95% of tetracycline in 60min. The reaction major active components were ∙O2-, ‧OH and h+, as acquired by active species capture experiments and EPR tests. Based on this, the manufacturing pathway for active compounds showed the electron transfer pathway and photocatalytic mechanism of Z-type heterojunction.

A novel 0D/2D Z-scheme heterojunction Bi2Sn2O7/Bi4O7 for boosting tetracycline photodegradation: Insight from performance to mechanism

The slow migration and low separation efficiency of charge carriers inhibit the photocatalytic degradation of pollutants in water. Constructing heterojunction is an effective strategy to enhance photocatalytic performance. Herein, a novel Z-scheme Bi2Sn2O7/Bi4O7 (BOBSO) heterojunction was designed and synthesized for degrading typical antibiotics in water. The 0.2BOBSO heterojunction exhibits excellent photocatalytic performance, achieving a 97.97 % tetracycline degradation rate under visible light irradiation, significantly surpassing the individual materials Bi2Sn2O7 (75.93 %) and Bi4O7 (18.61 %). The composite photocatalyst shows excellent stability and strong adaptability to environmental factors. Compared to Bi2Sn2O7 and Bi4O7, 0.2BOBSO heterojunction possesses superior microstructure and photoelectrochemical properties confirmed by various characterizations. The electron transfer mechanism of Z-scheme heterojunction on the composite surface was proposed according to in-depth analyses using UV–vis, Mott-Schottky, and Electron Spin Resonance (ESR). The formation of Z-scheme heterojunction accelerates the migration of photogenerated charge carriers while maintaining the optimal redox ability of the materials. Furthermore, quenching experiments confirm that h+, O2−, and 1O2 are the main active species in the reaction system, with TC degraded via both radical and non-radical pathways. This study provides new insights into the design and construction of 0D/2D Z-scheme heterojunction photocatalysts.

Constructing robust Z-type BiOBr/Br-doped g-C3N4 heterojunctions for visible light-assisted photocatalytic decontamination of norfloxacin

In order to remediate the environment in a green way, the development of new and effective photocatalytic heterojunctions has received great attention from researchers in recent years. Herein, we assembled BiOBr-decorated Br-doped g-C3N4 (BiOBr/BrCN) hybrid heterojunctions in different percentages (BiOBr content = 5–30 wt%) to achieve effective photocatalytic heterojunctions for visible-light-prompted degradation of antibiotic norfloxacin (NOR), in which reducing the photocarriers recombination rate. Obviously, BiOBr/BrCN composites endorsed greater photodecomposition performance of NOR under visible-light illumination. The 10 wt%BiOBr/BrCN photocatalyst decomposed 95.5 % of NOR in 1.5 h, which are approximately 2.5 and 1.7 times of enhancement compared with BrCN and BiOBr, respectively. The enlarged response to visible-light and the efficient separation of photo-induced carriers in the developed Z-system heterojunction between BiOBr and BrCN were behind the boosted photocatalytic activity. Besides, the trapping experiments demonstrated that both •O2− and h+ species take significant roles in the degradation of NOR antibiotic, which supports the proposed mechanism. In addition, the degradation efficiency displays an insignificant decrease after the fifth cycle, indicating that the synthesized BiOBr/BrCN photocatalyst system has a great stability for the practical applications.

2D/2D Bi2MoO6/g-C3N4 direct Z-scheme Van der Waals heterojunction photocatalyst for boosting nitrogen fixation

Although photocatalytic nitrogen fixation is an efficient and environmentally-friendly technology for ammonia synthesis, it still faces challenges such as high recombination of photo-generated carriers and a lack of active sites for the reaction of catalysts. Constructing direct Z-scheme heterojunctions is considered an effective strategy to enhance carrier separation efficiency of catalysts. However, it still encounters the challenge of lacking surface active reaction sites. The 2D Z-scheme Van der Waals heterojunction has the same charge transfer mechanism of direct Z-scheme heterojunctions, ensuring high carrier efficiency and retaining strong redox ability. Additionally, its layered structure provides a large number of reactive sites. In this study, theoretical calculation simulation was employed to predict the properties of Bi2MoO6 (BMO) and g-C3N4 (CN), and to simulate the dynamic behavior of photogenerated carriers. A 2D/2D CN-BMO direct Z-scheme Van der Waals heterojunction was constructed. Remarkably, this heterojunction demonstrated significantly enhanced photocatalytic ammonium generation capabilities. This study provides valuable insights for the development of advanced heterojunction photocatalysts.

Hollow amorphous N-doped TiO2 microspheres with uniform shell thickness and high carrier separation efficiency for photocatalytic of high-concentration Cr(VI)

Due to the low quantum efficiency, pure N-doped TiO2 (NTO) is still ineffective for catalyzing high concentrations of pollutants. In this study, a novel hollow amorphous NTO photocatalyst (AH-NTO) was synthesized by ultrasonic-assisted hydrothermal method and applied to photocatalysis of high-concentration chromium-containing wastewater. The hollow structure was constructed using a three-dimensional Fe3O4 template, and the shell layer thickness changed regularly compared to the stirring method, suggesting that ultrasound contributes to the formation of a uniform shell. Meanwhile, the low crystallization kinetics induced by the ultrasound-assisted low-temperature hydrolysis process enhance the generation and stability of amorphous NTO. Characterization of the system demonstrated that the hollow amorphous structure improved visible-light utilization efficiency (∼70% light transmittance) and specific surface area (182.95 m2·g-1). Furthermore, the optimal photocatalyst exhibited a high photogenerated carrier signal (0.231 μA·cm-2), low interface resistance (374.8 Ω), and a strong oxygen vacancy signal (∼0.38 a.u.), which provides favorable conditions for the separation and transfer of photogenerated carriers. Based on these properties, the photocatalyst effectively treated wastewater containing 0.274 g·L-1 of Cr(VI). The removal efficiency decreased by only 0.18% over five consecutive cycles, demonstrating excellent cycle stability and activity. Therefore, this work provides a practical case for treating high-concentration pollutants.

Cyanobacterial hydrothermal carbonization carbon as photocatalyst for selective aerobic oxidation of cyclohexane

The exploration of catalyst preparation techniques that incorporate environmental-friendly methodologies has consistently been the focus of scientific inquiry within the field of green synthesis of oxygen-containing organic chemicals. Herein, a metal-free hydrothermal carbonation carbon (HTCC) has been prepared utilizing cyanobacterial biomass produced during a water bloom in a freshwater lake. The HTCC produced is capable of performing photocatalytic selective oxidation of cyclohexane to cyclohexanol and cyclohexanone (KA oil) under ambient conditions. The use of cyanobacterial biomass allows for the efficient preparation of HTCC, which exhibits a conversion rate of cyclohexane that is 4.1 times of HTCC prepared with alternative carbon sources (glucose). The selectivity to KA oil over the samples are almost 100%. Characterizations and analysis reveal that cyanobacteria can lead to self-doping of nitrogen and hydrophobicity of the resulting HTCC, while sulfuric acid etching endow it with more photoactive sp2 hybridized structure units that contribute to a higher photogenerated carrier separation efficiency. The suitable band structure enables the cyanobacterial HTCC to produce superoxide radicals to oxidize cyclohexane. These findings are of great significance for the development of eco-friendly photocatalysts and the utilization of biomass resources.

Controllable fabrication of the luminescent photocatalytic material AgB/SMSO for application in cement: Optimization of doping strategies and all-weather degradation of pollutants

This paper presents an innovative luminescent photocatalytic material, Ag3PO4/BiVO4/Sr2MgSi2O7:(Eu2+, Dy3+) (AgB/SMSO), which overcomes a pivotal limitation of photocatalysts—dependence on a light source—and effectively remediates pollutants and augments cement-based composite properties. The efficient carrier separation facilitated by Ag3PO4, in conjunction with the broad spectral response of BiVO4, enables AgB/SMSO to harness the internal luminescent properties of SMSO as a persistent light source, achieving continuous degradation of pollutants, which reveals the exceptional afterglow characteristics and photocatalytic activity of AgB/SMSO. At a 1:1:40 ratio, AgB/SMSO maintained its catalytic efficacy for over 8 h in the dark (methylene blue degradation rate of 70.43%), surpassing the 3-hour limit of current luminescent photocatalysts. Furthermore, the impact of integrating AgB/SMSO with cement on early-stage cement hydration, morphology, and micromechanical properties was comprehensively assessed. Ultimately, the overall photocatalytic capability of the derived AgB/SMSO cement-based composites was evaluated through experiments, revealing the synergistic mechanisms involved. This study not only enriches the theoretical understanding of photocatalysis but also provides a robust technical foundation for the innovation of environmentally friendly building materials and the advancement of sustainable urban development.

Efficient photo-assisted reduction of Cr(VI) via activated carbon mediated Z-scheme FeS2/α-FeOOH/C heterojunction: Focusing on molecular oxygen fate and synergetic reduction mechanism

Herein, pyrite (FeS2), goethite (α-FeOOH) and activated carbon (C) were combined to construct FeS2/α-FeOOH/C composites with C mediated Z-scheme heterojunction for efficient photo-assisted Cr(VI) reduction. Characterization tests indicated the strong interaction via Fe-O-C and C-S-C, the increased amount of crystal defects and surface oxygenic functional groups, and the decreased agglomeration degree during combination strengthened electron transport and visible light conversion efficiency, resulting in synergistic effect for enhanced Cr(VI) removal. Additionally, C mediated Z-scheme heterojunction with lower resistance facilitated the transfer and separation efficiency of photo-generated carriers, further accelerating Cr(VI) reduction. Consequently, almost 100 % of Cr(VI) was reduced via FeS2/α-FeOOH/C in 60 min, 4 times that of pristine FeS2. Quenching, EPR and control experiments confirmed photocatalysis made more contribution than single reductive reagents (FeS2) in Cr(VI) reduction. The specific contribution rate of reductive species like e−, Fe2+, S22− and •O2− in this complicated system was firstly detailedly demonstrated and •O2− played a predominant role under oxic condition. Meanwhile, oxidative species like H2O2, 1O2 and •OH ascribed to DO activation or photo-generated h+ preferred to reacted with Fe2+ and S22− with higher reducibility and-only delayed Cr(VI) reduction rate. Hence, the final total Cr(VI) removal efficiency and generated Cr(III) kept stable in oxic solution.

Two-dimensional QDs-Co-CuS1-x/Ti3C2/TiO2 heterojunction with synergistic unsaturated bimetal sites and sulfur vacancies for highly selective photocatalytic CO2 reduction

The primary factors that determine the efficiency and selectivity of multi-electron photoreduction of CO2 include the chemical properties of the active sites, as well as the kinetics of charge separation and transfer. Herein, a novel two-dimensional QDs-Co-CuS1-x/Ti3C2/TiO2 heterojunction is developed, with Co-CuS1-x quantum dots serving as cocatalysts and Ti3C2 MXene as an effective electron transfer channel. The anchoring effect of Ti3C2 facilitates the formation of robust TiS bonds with Co-CuS1-x, thereby promoting efficient separation and transfer of photoelectrons to the Co-Cu bimetallic active sites. This process enhances the local electron density at these sites and accelerates the kinetics of electron transfer to absorbed CO2. The recyclability of the Co-Cu sites is also significantly enhanced by continuous photoelectron injection. Importantly, DFT calculations indicate that the synergistic dual sites involving highly exposed Co-Cu and S vacancies promote rate-determining step from COO* to COOH*, which may account for the highly selective photoreduction of CO2-to-CO. Benefitting from the synergic effects of the active sites and efficient separation of carriers, the optimized Co-CuS1-x/Ti3C2/TiO2 exhibits a satisfactory CO photoreduction rate of 30.8 µmol∙g−1∙h−1, with an excellent selectivity of 87.9 % and apparent quantum yield of 0.61 % in the absence of any sacrificial reagents, which is 6.5 times higher than Co-CuS1-x, 54.0 times than Ti3C2Tx/TiO2.

Schottky junctions integrated with S-scheme heterojunctions in recyclable loaded ZnIn2S4/UiO-66/calcined graphite felt photocatalysts with enhanced carrier separation for photocatalytic degradation

Photocatalytic technology holds significant potential in the purification of antibiotic wastewater. However, efficient carrier separation and convenient recyclability are crucial for the practical application of photocatalysts. Herein, a loaded ZnIn2S4/UiO-66/calcined graphite felt (ZU/C-GF) composite photocatalyst was demonstrated to achieve efficient and stable removal of tetracycline hydrochloride (TCH) from water. Detailed characterization and theoretical calculations suggested that ZnIn2S4 could form a Schottky junction with C-GF and an S-scheme heterojunction with UiO-66. The internal electric field (IEF) at the interface could promote the migration of photoelectrons, while the Schottky barrier could inhibit electron backflow. This synergistic strategy maximized the separation of photogenerated electrons and holes, thereby enhancing the photocatalytic performance. The optimal composite material exhibited the highest removal efficiency (97.0 %) and reaction rate (0.02312 min−1) while maintaining comparable degradation performance under solar irradiation. Additionally, this C-GF-based immobilization scheme allowed for rapid recovery and reuse of the photocatalyst, effectively addressing the challenge of recycling. ZU-10/C-CF demonstrated stable reusability after five consecutive cycles, revealing its significant potential for practical applications. This work presents novel insights for coupling Schottky junctions and S-scheme heterojunctions, and describes a more convenient approach for the continuous and stable treatment of antibiotic wastewater.

Construction of Lamellar CoFe-LDHs@MoS2 to Promote Permonosulfate Properties Leading to Effective Photocatalytic Degradation of Norfloxacin

The utilization of the photo catalytic activation of permonosulfate (PMS) for the combined breakdown of pollutants has become a focal point in research. Layered double hydroxides (LDHs) have a unique layered structure which is conducive to the adsorption and diffusion of reactants, and can provide more active sites for photocatalytic reactions. The anions between the layers can be exchanged with a variety of substances so that specific catalytically active species can be introduced as needed. LDHs themselves have certain catalytic activity, which can produce synergistic catalysis between LDHs and the supported photocatalytic active substances, and further improve the degradation effect of antibiotics. In actual wastewater treatment, LDHs as a catalyst carrier have a good application prospect. However, the poor activation effect is attributed to the low separation efficiency of catalyst carriers and insufficient active sites. In this study, a dual active site system consisting of Co and Fe, known as CoFe-LDHs@MoS2, was developed as a catalyst to facilitate the synergistic degradation of norfloxacin (NOF) by PMS under visible light. The findings demonstrate that the material possesses an effective capacity for the synergistic degradation of NOF. A comprehensive investigation was conducted to assess the impact of different catalysts, PMS dosage, degradation systems (Vis, PMS, or Vis PMS), catalyst dosage, NOF concentration, pH, and cycle times on the degradation performance. The active free radicals, degradation pathways, and intermediate toxicity were elucidated through capture experiments, Electron Paramagnetic Resonance Spectrometer (ESR) analysis, a liquid mass spectrometry (LC-MS) toxicity assessment, and theoretical calculations. This research offers a novel approach for designing catalysts with exposed high activity sites for the effective removal of NOF from environmental water.

Oxygen vacancy enriched and Cu single-atom contained covalent organic frameworks: A competitive photocatalyst to promote hydrogen evolution under visible light

Single-atom loaded covalent organic frameworks (COFs) have been rapidly developed in the field of photocatalytic hydrogen production in recent years. Despite the insufficient active sites has been introduced, the high recombination rate of photogenerated carriers has hindered the progress of catalyst development. In this work, a novel approach is proposed to construct oxygen vacancies (OVs) on single atom Cu contained COF-TpPa, acting as an electron collector to facilitate the transfer and utilization of electrons. The Cu-OV-TpPa can provide a remarkable H2 production rate of 2.77 mmol g−1 h−1 under visible light, which is 2.6 times of Cu-P-TpPa (a H2 production rate of 1.02 mmol g−1 h−1). It achieves a high apparent quantum efficiency (AQE) of 20 % at 420 nm with no noble metal cocatalyst. A thorough analysis of carrier lifetime, recombination rate, electric conductivity and charge density reveals that the synergistic effect between OVs and single-atom Cu significantly enhances photogenerated carrier separation efficiency and reduces activation energy. This study presents a new strategy to design COF-based photocatalysts towards a competitive H2 production under visible light.

Nitrogen-deficient C3N4 coupled with AgBr construction Z-scheme heterojunction form double electric field to promote photogenerated carrier separation enhancement hydrogen evolution

g-C3N4 is an excellent and affordable photocatalyst, but its weak built-in electric field slows down its photogenerated carrier separation rate. Meanwhile, modulating the interfacial electric field is also an effective way to increase the light-generated carrier separation efficiency. In this study, the built-in electric field of g-C3N4 is enhanced by using N vacancies (from 0.742 V to 0.868 V). Subsequently, the modified Nv-C3N4 (N0CN) is utilized to create a heterojunction with AgBr to generate a synergistic effect of built-in and interfacial electric fields (from 0.868 V to 1.032 V). The photogenerated carrier separation was significantly enhanced by the synergistic interaction of the dual electric fields, leading to a notable improvement in the photocatalytic efficiency of A-N0CN. The H2 production performance reached 1884.6 µmolg-1h−1, which was measured 1047 times higher than that of N0CN (1.8 µmolg-1h−1), A-CN (969.9 µmolg-1h−1) and CN (1.1 µmolg-1h−1), representing increases of 1.94 and 1713 times, respectively. This research offers a new perspective for catalyst design involving dual electric field synergy.

Constructing a novel Bi2MoO6/TiO2/Ti3C2 composite with efficient carrier separation for excellent photocatalytic purification of TC

Photocatalytic removal of tetracycline (TC) from wastewater is an advantageous method with green and efficient potentials, while the low light utilization and severe charge carrier recombination of conventional photocatalysts limit their practical application. The TiO2/Ti3C2 derived from in-situ partly oxidation of Ti3C2 MXene precursors on which Bi2MoO6 (BMO) was tightly loaded was synthesized via a facile hydrothermal synthesis route. The introducing TiO2/Ti3C2 accelerated the transfer of electrons, improving the efficiency of electron-hole separation, thus strengthened the photocatalytic performance. Under optimum conditions, the BMO/TiO2/Ti3C2 composite significantly removed 87.54 % TC from wastewater within 150 min, which was higher than the original counterparts and remained almost unchanged after four cycles. The active species trapping experiments and ESR analysis displayed that •O2- played a dominant role in TC degradation. The possible degradation pathways were also deduced through liquid chromatography-mass spectrometry (LC-MS) analysis experiments, demonstrating that the terminal products of degradation were mainly CO2 and H2O, confirming the potential of BMO/TiO2/Ti3C2 photocatalyst for the environmentally friendly treatment of antibiotic pollutants in wastewater.

Hierarchical porous structured biomass based COFs for photocatalytic oxidative coupling of amines

Covalent Organic Frameworks (COFs) are widely used for photocatalysis but limited by the aggregation of the catalysts, which limited the mass transfer. Herein, corn stalk cores were used as the substrate, and two kinds of biomass based COFs with different electronic structures of thiophene (C@SCOF) and pyridine (C@NCOF) were in-situ fabricated uniformly on the surface of the substrate. In this way, COFs expose more active sites rather than embedding in the agglomerated structure. Biomass based COFs, especially C@SCOF, exhibit a hierarchical porous structure containing micropores and macropores, which offer fast mass transfer channels for the catalytic and adsorbed substrates. Therefore, the biomass based COFs utilized more efficiently to achieve higher photocatalytic performance. The C@SCOF with D-A structure displays stronger photoresponse and lower impedance, which promote the dissociation of a photogenerated exciton and carrier separation efficiency, resulting remarkable photocatalytic performance for oxidation of benzylamine coupling reaction. This work could guide the design and preparation of biomass-based hybrids with promising performance.

Enhanced Charge Transfer in Poly(Heptazine Imide) Synergistically Induced by Donor-Acceptor Motifs and Ohmic Junctions for Efficient Photocatalytic CO2 Reduction.

Poly(heptazine imide) (PHI) has received widely interest in the photocatalytic CO2 reduction due to its good crystallinity and complete in-plane structure. However, its poor photo-induced carrier separation and migration efficiency and insufficient active sites results in undesirable photocatalytic CO2 reduction performance. Herein, we designed and constructed a novel ohmic junction photocatalyst by integrating melamine edge-modified PHI (mel-PHI) with extended π-conjugated system with TiN (TiN/mel-PHI) for enhancing the photocatalytic CO2 reduction activity. Strikingly, the photocayalytic CO2 reduction yield of the optimal TiN/mel-PHI is 62.64 µmol·g-1·h-1, which is 5.6 and 2.8 times higher than PHI (11.26 µmol·g-1·h-1) and mel-PHI (22.32 µmol·g-1·h-1), respectively. The superior photocatalytic CO2 reduction activity is attributed not only to the formation of D-A structure by the introduction of melamine, which extends the π-conjugation system, alters the electronic structure of PHI, and accelerates the charge separation and migration, but also to the induced internal electric field by ohmic junction further enhances the charge separation and migration efficiency. Meanwhile, the synergistic effect of mel-PHI and TiN enriched the electron number of TiN, reducing the CO2 reduction potential. This work highlights the synergistic enhancement of charge transfer between D-A motifs and ohmic junctions, confirming their potential in optimizing photocatalysts.