The enhanced photocatalytic performance of CPAA doping with different concentrations of Titanium oxide nanocomposite against MB dyes under simulated sunlight irradiations

The pure conjugated polyarylene azomethine (CPAA) and its nanocomposites (CPAA-TiO2) with different concentrations of TiO2 nanoparticles were successfully prepared by in-situ technique and analyzed by different advanced techniques. XRD has confirmed the structural properties and crystallinity of (CPAA) and nanocomposites. The SEM clearly shows that the (CPAA) is uniform and homogeneous, with tightly connected aggregate layers in shape. However, the amount of TiO2 in the nanocomposites greatly affects their morphology, revealing structural differences and indicating a reaction between (CPAA) and TiO2, especially at a higher concentration of 5% TiO2. A new composite of (CPAA) was introduced and the photocatalytic effect for MB was studied. The removal efficiency of (pure-CPAA) over MB dye under simulated sunlight was 62%. However, (CPAA-TiO2 1%) destroyed 90% of MB dyes. It was discovered that the low band gap of (CPAA-TiO2 1% (2.84 eV)) accelerates high electron-hole recombination, increasing photocatalytic activity.

ZIF-derived oxygen vacancy-rich Co3O4 for constructing an efficient Z-scheme heterojunction to boost photocatalytic water splitting

With ZIF-67 as the precursor, oxygen vacancy-rich Co3O4 nanoparticles were derived and anchored on the surface of 2D polyimide (PI) to construct a Z-scheme hybrid heterojunction (20ZP) through a simultaneous solvothermal in situ crystallization and polymerization strategy. XRD, XPS and EPR confirmed that both Co(III) and oxygen vacancies are formed during the low temperature conversion of ZIF-67 to Co3O4 nanoparticles that in turn accelerate the polymerization of PI. Synchronous crystallization makes the interfacial architecture intermetal and compact, inducing a strong interfacial electronic interaction between Co3O4 nanoparticles and PI. UV-vis DRS spectra and transient photocurrent response demonstrate that the incorporation of Co3O4 on polyimide not only extends the light absorption in the visible range, but also enhances the charge transfer rate. EIS, TRPL techniques and DFT calculations have confirmed that the photoinduced interfacial charge transfer pathway of this hybrid heterojunction characterized the Z-scheme in which the photoinduced electrons transfer from the conduction band of Co3O4 to the valence band of PI, significantly inhibiting the recombination of electrons and holes within PI. More importantly, the oxygen vacancies located below the conductor band of Co3O4 can deepen the band bending, improve the charge separation efficiency and accelerate electron transfer between Co3O4 and PI. This Z-scheme hybrid heterojunction structure can not only maintain the high reducing capacity of photoinduced electrons on the conductor band of PI, but also enhance the oxidative capacity of the heterojunction composite material, thus promoting the overall progress of the photocatalytic hydrogen release reaction.

Revolutionizing carbon chemistry: Solar-powered C(sp3 )-N bond activation and CO2 transformation via newly designed SBE-Y cutting-edge dynamic photocatalyst

A solvent-free sulfur-bridge-eosin-Y (SBE-Y) polymeric framework photocatalyst was prepared for the first time through an in situ thermal polymerization route using elemental sulfur (S8 ) as a bridge. The addition of a sulfur bridge to the polymeric framework structure resulted in an allowance of the harvesting range of eosin-Y (E-Y) for solar light. This shows that a wider range of solar light can be used by the bridge material's photocatalytic reactions. In this context, supercharged solar spectrum: enhancing light absorption and hole oxidation with sulfur bridges. This suggests that the excited electrons and holes through solar light can contribute to oxidation-reduction reactions more potently. As a result, the photocatalyst-enzyme attached artificial photosynthesis system developed using SBE-Y as a photocatalyst performs exceptionally well, resulting in high 1,4-NADH regeneration (86.81%), followed by its utilization in the exclusive production of formic acid (210.01 μmol) from CO2 and synthesis of fine chemicals with 99.9% conversion yields. The creation of more effective photocatalytic materials for environmental clean-up and other applications that depend on the solar light-driven absorption spectrum of inorganic and organic molecules could be one of the practical ramifications of this research.

Band Structure Engineering of Polyimide Photocatalyst for Efficient and Selective Oxidation of Biomass-Derived 5-Hydroxymethylfurfural

Solar-driven high-value utilization of biomass and its derivatives has attracted tremendous attention in replacing fossil sources to generate chemicals. Developing high-performance photocatalysts to selectively catalyze bio-platform molecules remains a challenge. Herein, biomass-based 5-hydroxymethylfurfural (HMF) was efficiently and selectively photooxidized to 2, 5-diformylfuran (DFF) using a metal-free polyimide (PI). PI with moderate photooxidation capacity delivered high DFF selectivity of 91 % and high apparent quantum efficiency of 1.13 %, nearly 7 times higher than that of graphitic carbon nitride. Experimental measurements and theoretical calculations revealed that the band structure and photooxidation capability of PI can be continuously modulated by varying the molar ratio of amine and anhydride. Mechanism analysis depicted that holes and superoxide radicals play crucial roles in the efficient photooxidation of HMF to DFF. This work provides guidance on designing efficient polymeric photocatalysts for oxidating biomass and its derivatives to value-added chemicals.

Preparation of novel diperylene-cored polyimide photocatalyst with broad-spectra response and high stability

A novel polyimide (PI) with broad-spectra response, high photocatalytic activity and stability under super acidic conditions (pH = 0) was synthesized via polymerizing method. Two types of perylene-cored materials (PDIAN and PTCDA) with anhydride and diamine respectively, were applied as precursors for PI polymerization. The as-prepared PI was optimized at 1:1 initial molar ratio of PDIAN to PTCDA. Using common PI (synthesized from melamine and pyromellitic dianhydride) as comparison, the Cr(VI) reduction rate was boosted from 25.4% to 96.6% within 120 min light irradiation. The corresponding rate constant by PI(PDIAN/PTCDA) was estimated to be ca. 11.7 times relative to that by common PI. The boosted performance was ascribed to the strong π-π conjugation from diperylene cores, which can decrease the photoluminescence intensity and electrochemical impedance, so as to promote the separation and transfer of photogenerated electron-hole pairs. In addition, the optimized PI(PDIAN/PTCDA) displayed wide-spectra response, which can still work under 730 nm light. The influencing factors toward Cr(VI) reduction were also clarified to be beneficial at lower pH and increased concentration of hole scavenger. After five cycles at pH 0, the PI still maintained excellent redox activity and structural stability.

Nanoarchitecture of a Two-Dimensional Few-Layer Graphene Oxide/π-Conjugated Polyimide Composite for Enhanced Photocatalytic Performance

A novel two-dimensional graphene oxide/sulfur-doped polyimide (GO/SPI) hybrid polymer photocatalyst was synthesized by a facile ultrasonic chemical method. The characterization results showed that the skeleton structure of SPI was not changed when the few layers of GO were wrapped on the surface. Due to the excellent charge transport characteristics of GO and the strong π-π stacking interaction between two-dimensional GO and SPI, the photogenerated carrier transport capability of the GO/SPI composites was significantly enhanced compared with that of SPI. The efficient transmission and separation of photogenerated charge carriers significantly improve the photocatalytic degradation of the methyl orange activity of the GO/SPI composite. This work provides a facile and new way for the synthesis of metal-free inorganic-organic composite photocatalysts with high efficiency and low cost.

Anchoring Co3O4 nanoparticles on conjugated polyimide ultrathin nanosheets: construction of a Z-scheme nano-heterostructure for enhanced photocatalytic performance

Efficient utilization of solar energy for photocatalytic hydrogen production and degradation of organic pollutants is one of the most promising approaches to solve the energy shortage and environmental pollution. A series of Co₃O₄/sulfur-doped polyimide (CO/SPI) direct Z-scheme nano-heterostructure photocatalysts was successfully prepared via a facile green thermal treatment method. The effects of Co₃O₄ nanoparticles on the structure, morphology, and optoelectronic properties of CO/SPI composite samples were systematically characterized by different spectroscopic methods. Characterization results confirmed that Co₃O₄ nanoparticles as an acid oxide catalyst promoted the oxidation stripping of bulk SPI to form SPI ultrathin nanosheets. Thus, the Co₃O₄ nanoparticles were firmly embedded on SPI ultrathin nanosheets to construct a direct Z-type CO/SPI nanostructure junction. Therefore, the activity and cycle stability of photocatalytic water splitting for hydrogen production and organic pollutant degradation were greatly improved under solar light irradiation. In particular, the 0.5CO/SPI composite sample displayed the highest activity with an average production rate of 127.2 μmol g^-1 h^-1, which is nearly 13 times and 106 times higher than that of SPI and Co₃O₄. This work provides a new avenue for constructing efficient inorganic-organic nanoheterostructured Z-type photocatalysts and takes an important step towards the efficient utilization of renewable energy.

Construction of Direct Z-Scheme SnS2 Quantum Dots/Conjugated Polyimide with Superior Photocarrier Separation for Enhanced Photocatalytic Performances

In this study, a novel direct Z-scheme SnS₂ quantum dots/sulfur-doped polyimide (SQDs/SPI) photocatalyst was firstly fabricated by an in situ crystallization growth of SnS₂ quantum dots on sulfur-doped polyimide through a facile hydrothermal method. The photocatalytic hydrogen production activity of 5SQDs/SPI samples reached 3526 μmoL g^-1 in the coexistence of triethanolamine and methanol used as hole sacrificial agents, which is about 13 times higher than that of SPI under the same conditions and 42 times higher than that of SPI only as a hole sacrificial agent. The improvement can be related to the direct Z-scheme charge transfer in the tight interface between SQDs and SPI, which promoted rapid separation and significantly prolonged the lifetime of photoexcited carriers. The Z-scheme charge transfer mechanism was proposed. This discovery comes up with a new strategy for the development of an efficient, environmentally friendly, and sustainable sulfide quantum dots/polymer non-noble metal photocatalyst.

Redox-active polyimides for energy conversion and storage: from synthesis to application

As the demand for next-generation electronics is increasing, organic and polymer-based semiconductors are in the spotlight as suitable materials owing to their tailorable structures along with flexible properties. Especially, polyimide (PI) has been widely utilised in electronics because of its outstanding mechanical and thermal properties and chemical resistance originating from its crystallinity, conjugated structure and π-π interactions. PI has recently been receiving more attention in the energy storage and conversion fields due to its unique redox activity and charge transfer complex structure. In this review, we focus on the design of PI structures with improved electrochemical and photocatalytic activities for use as redox-active materials in photo- and electrocatalysts, batteries and supercapacitors. We anticipate that this review will offer insight into the utilisation of redox-active PI-based polymeric materials for the development of future electronics.

Eu(III) Functionalized Crystalline Polyimide Hydrogel Film as a Multifunctional Platform for Consecutive Sensing of Spermine and Copper Ions

In this study, a novel Eu(III) functionalized crystalline polyimide hydrogel film (Eu-1) is fabricated by incorporating highly stable polyimide (PI) into a sodium alginate (SA) matrix, followed by cross-linking reaction with Eu³⁺ ions. Based on different fluorescence responses, Eu-1 is used for the consecutive detection of spermine (Spm) and copper ions (Cu²⁺). Eu-1 can be employed as a sensor for polyamine, especially for Spm with significant fluorescence enhancement based on the "turn on" mode. The fluorescent sensor Eu-1@Spm constructed by the Eu-1 and Spm can be further used as a "turn off" sensor to quantitatively monitor Cu²⁺. The good selectivity combined with the low detection limit of the sensor meets the requirements for monitoring Cu²⁺. The possible luminescence response mechanisms to Spm and Cu²⁺ have been studied through experimental data and theoretical calculations. In addition, a back-propagation neural network (BPNN) model based on an Eu-1@Spm sensor is constructed, which can accurately distinguish Cu²⁺ concentrations by deep machine learning (ML). This work not only puts forward a facile method to prepare a novel Eu-functionalized PI-based hybrid film but also demonstrates the potential of PI-based film materials for fluorescence detection.

Molecular Design of Two-Dimensional Covalent Heptazine Frameworks for Photocatalytic Overall Water Splitting under Visible Light

Photocatalytic water splitting sustainably offers clean hydrogen energy, but it is challenging to produce low-cost photocatalysts that split water stoichiometrically into H₂ and O₂ without sacrificial agents under visible light. Here, we designed 17 two-dimensional (2D) covalent heptazine frameworks (CHFs) by topologically assembling heptazine and benzene-containing molecular units that provide active sites for hydrogen and oxygen evolution reactions, respectively. Among them, 12 CHFs have band gap values of <3.0 eV with band margins straddling the chemical reaction potential of H₂/H⁺ and O₂/H₂O. In particular, a 2D H@DBTD CHF based on heptazine and 4,7-diphenyl-2,1,3-benzothiadiazole is a potential photocatalyst with a band gap of 2.47 eV for overall water splitting, which was confirmed with the calculated Gibbs free energy, non-adiabatic molecular dynamics, and preliminary experiment. This study presents an experimentally feasible molecular design of 2D CHFs as metal-free photocatalysts for overall water splitting under visible light.

One-Step construction of Polyimide/NH2-UiO-66 heterojunction for enhanced photocatalytic degradation of sulfonamides

Photocatalysis treatment is a promising technology to eliminate water pollutants. Herein, we constructed polyimide/NH₂-UiO-66 composites (PUs) through a facile one-step solvothermal method for the photocatalytic degradation of sulfonamides. The optimized photocatalyst PU1.5 was superior to the photocatalysts prepared through multi-step methods due to the more exposed (001) facets of polyimide and the better distribution of small NH₂-UiO-66 particles. PU1.5 showed the highest photocatalytic activity, which was 9.5 and 92.0 times higher than that of polyimide and NH₂-UiO-66. Such improvement was attributed to the improved carrier separation efficiency resulted from direct Z-scheme heterojunction. The probable degradation pathway of sulfathiazole was proposed by the LC-MS/MS and Density Functional Theory (DFT) calculation. Furthermore, the reduced toxicity and the little antibacterial activity of intermediates was investigated by the Quantitative Structure-Activity Relationship (QSAR) analysis and the residual antibiotic activity experiment. The study might provide a new strategy for designing composite photocatalyst to achieve efficient removal of pollutants.

Construction of α-Fe2O3/Sulfur-Doped Polyimide Direct Z-Scheme Photocatalyst with Enhanced Solar Light Photocatalytic Activity

A novel two-dimensional α-Fe₂O₃/sulfur-doped polyimide (FO/SPI) direct Z-scheme photocatalyst was successfully constructed by a facile thermal treatment method. The effects of α-Fe₂O₃ nanosheets on the morphology, chemical structure, and photoelectronic properties of FO/SPI composites were systematically characterized by different spectroscopic means. These methods include X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, transient fluorescence spectra, and so forth. It was confirmed that the small amounts of α-Fe₂O₃ can availably facilitate exfoliation of bulk SPI, resulting in a transformation of SPI from bulk to 2D layered composite that illustrates tight interface through the coordination Fe-N bond and an all-solid-state direct Z-scheme junction. Thus, the transfer and separation efficiency of photogenerated electron/hole pairs were significantly enhanced, which greatly promoted improvement of the photocatalytic activity of the FO/SPI composite for methyl orange degradation under solar light. This work provides a new approach to constructing efficient inorganic-organic Z-scheme photocatalyst based on strong interface interaction.

Facile fabrication of Tb3+-functionalized COF mixed-matrix membrane as a highly sensitive platform for the sequential detection of oxolinic acid and nitrobenzene

A novel Tb³⁺-functionalized covalent organic framework-based polymer mixed-matrix membrane (Tb³⁺@COF MMM) has been successfully fabricated by incorporating the highly stable Tb³⁺@PI-COF as filler into polyvinylidene fluoride (PVDF) solution. Compared with pure COF membrane, MMM exhibits its good flexibility, processability and high detection sensitivity. The obtained Tb³⁺@COF-MMM (M) can be employed as a highly sensitive sensing platform for the sequential detection of oxolinic acid (OA) and nitrobenzene (NB) based on a "off-on-off" process. M has performed its great selectivity, high sensitivity, and low detection limit for detecting OA with "turn-on" mechanism. Moreover, owing to the good chemical stability and anti-interference of M sensor, it is prospective to efficiently detect residues of OA in serum or river water. After the detection of M-15 toward OA, the obtained fluorescent M-15/OA exhibits the rapid quenching, facile manipulation, cycling utility and low detection limits for sensing NB solution and vapor. This work has proposed a typical case of developing flexible Ln³⁺-functionalized COF-based polymer mixed-matrix membrane as a highly sensitive sensing platform for detecting OA and NB, simultaneously revealed the applied potentiality of M for monitoring animal health and environmental pollution.

Greener One Step Synthesis of Novel In-situ Selenium-Doped Frameworks Photocatalyst by Melem and Perylene Dianhydride for Enhanced Solar Fuel Production from CO2

To minimize the ever-increasing global warming and environmental problems, the conversion of atmospheric CO₂ into value-added solar chemicals/fuels is one of the most challenging tasks. As a means to accomplish this, herein we have synthesized first time novel in situ selenium doped polyimide frameworks (Se-PIFs) photocatalyst via thermal co-polymerization approach between melem (M) and perylene 3, 4, 9, 10- tetracarboxylic dianhydride (PTDA) along with selenium (Se) as a dopant. The Se-PIFs photocatalyst shows outstanding photocatalytic stability and activity for high solar fuel production (HCOOH ~ formic acid) from CO₂ . The solar light active Se-PIFs photocatalyst was demonstrating the ~ 10 fold higher photo-conversion of CO₂ to formic acid with yields of 250. 6 μmol. The current work is providing a facile and scalable avenue as well as sheds light on creating a new route for in-situ judicious design highly efficient Se-PIFs photocatalyst. The outcome are a benchmark instance for the use of selenium doped polyimide frameworks as a highly practical and efficient solar light active photocatalyst for carrying out the selective production of formic acid from environmental CO₂ .

Mechanochemically-Assisted Synthesis of Polyimides

Polyimides were obtained in 99 % yield in under 1 h through the "beat and heat" approach, involving solvent-free vibrational ball milling and a thermal treatment step. The influence of a plethora of additives was explored, such as Lewis acids, Lewis bases, and dehydrating agents, and the mechanochemical reaction was identified to run via a polyamic acid intermediate. The protocol was adopted to a range of substrates inaccessible through solution-based processes, including perylene tetracarboxylic acid dianhydride and melamine. Furthermore, quantum chemical calculations were conducted to identify the water removal as the crucial step in the reaction mechanism. The presented method is substantially faster and more versatile than the solution-based process.

Synthesis of phenol esters by direct C–H activation of aldehydes using a highly efficient and reusable copper-immobilized polyimide covalent organic framework (Cu@PI-COF)

In the present study, we report the design and fabrication of a thermally and chemically stable copper-based polyimide covalent organic framework (Cu@PI-COF) via a facile and straightforward synthetic approach for the oxidative esterification of aldehydes.

Design and application of metal-organic frameworks and derivatives as heterogeneous Fenton-like catalysts for organic wastewater treatment: A review

Advanced oxidation process (AOP), with a high oxidation efficiency, fast reaction speed (relatively no secondary pollution), has become one of the core technologies of industrial wastewater and advanced drinking water treatment. Heterogeneous Fenton-like oxidation process (HFOP) is a kind of AOP, which developed rapidly in recent years in such a way to overcome the disadvantages of traditional Fenton reaction. Metal-organic frameworks (MOFs) and their derivatives become essential heterogeneous catalysts for organics mineralization due to the large specific surface area, abundant active sites, and ease of structural regulation. However, the knowledge gap on the mechanism and the fate of heterogeneous catalyst species during organics degradation activities by MOFs presents considerable impediments, particularly for a wide application and scaling up the process. This work has the potential to provide guidance and ideas for researchers and engineers in the fields of environmental remediation, environmental catalysis and functional materials. This review focuses on clarifying the critical mechanism of •OH production from MOFs and derivatives as well as its action on the organic's degradation process. The recent developments in MOF based HFOP are compared, and more attention is paid for the following aspects in this review: (1) classifies systematically progressive modification methods of MOFs by chemical and physical treatments; (2) analyzes the fate of catalytic species during treating organic wastewater; (3) proposes design ideas and principles for improving the performance of MOFs catalysts; (4) discusses the main factors influencing the catalytic properties and practical application; (5) summarizes the possible research challenges and directions for MOFs and their derivatives as catalysts applied to wastewater treatment in the future.

Crosslinked porous polyimides: structure, properties and applications

Porous polyimides (pPIs) represent a fascinating class of porous organic polymers (POPs). Here the properties and functions of amorphous and crystalline pPIs are reviewed, and applications contributing to solutions to global challenges highlighted.

Polyimide with enhanced π stacking for efficient visible-light-driven photocatalysis

Polyimide photocatalysts with enhanced π stacking are prepared through the solvothermal condensation of pyromellitic dianhydride and N,N-dialkylmelamine, exhibiting extended light absorption ranges and efficient visible-light-driven photocatalysis.

Recent Advances in Conjugated Polymers for Visible-Light-Driven Water Splitting

With the ambition of solving the challenges of the shortage of fossil fuels and their associated environmental pollution, visible-light-driven splitting of water into hydrogen and oxygen using semiconductor photocatalysts has emerged as a promising technology to provide environmentally friendly energy vectors. Among the current library of developed photocatalysts, organic conjugated polymers present unique advantages of sufficient light-absorption efficiency, excellent stability, tunable electronic properties, and economic applicability. As a class of rising photocatalysts, organic conjugated polymers offer high flexibility in tuning the framework of the backbone and porosity to fulfill the requirements for photocatalytic applications. In the past decade, significant progress has been made in visible-light-driven water splitting employing organic conjugated polymers. The recent development of the structural design principles of organic conjugated polymers (including linear, crosslinked, and supramolecular self-assembled polymers) toward efficient photocatalytic hydrogen evolution, oxygen evolution, and overall water splitting is described, thus providing a comprehensive reference for the field. Finally, current challenges and perspectives are also discussed.

Molecular Engineering of Fully Conjugated sp2 Carbon-Linked Polymers for High-Efficiency Photocatalytic Hydrogen Evolution

The diverse nature of organic precursors offers a versatile platform for precisely tailoring the electronic properties of semiconducting polymers. In this study, three fully conjugated sp² carbon-linked polymers have been designed and synthesized for photocatalytic hydrogen evolution under visible-light illumination, by copolymerizing different C₃ -symmetric aromatic aldehydes as knots with the 1,4-phenylene diacetonitrile (PDAN) linker through a C=C condensation reaction. The hydrogen evolution (HER) is achieved at a maximum rate of 30.2 mmol g^-1  h^-1 over a polymer based on 2,4,6-triphenyl-1,3,5-triazine units linked by cyano-substituted phenylene, with an apparent quantum yield (AQY) of 7.20 % at 420 nm. Increasing the degree of conjugation and planarity not only extends visible-light absorption, but also stabilizes the fully conjugated sp² -carbon-linked donor-acceptor (D-A) polymer. Incorporating additional electron-withdrawing triazine units into the D-A polymer to form multiple electron donors and acceptors can greatly promote exciton separation and charge transfer, thus significantly enhancing the photocatalytic activity.

Nanoscale boron carbonitride semiconductors for photoredox catalysis

The conversion of solar energy to chemical energy achieved by photocatalysts comprising homogeneous transition-metal based systems, organic dyes, or semiconductors has received significant attention in recent years. Among these photocatalysts, boron carbon nitride (BCN) materials, as an emerging class of metal-free heterogeneous semiconductors, have extended the scope of photocatalysts due to their good performance and Earth abundance. The combination of boron (B), carbon (C), and nitrogen (N) constitutes a ternary system with large surface area and abundant activity sites, which together contribute to the good performance for reduction reactions, oxidation reactions and orchestrated both reduction and oxidation reactions. This Minireview reports the methods for the synthesis of nanoscale hexagonal boron carbonitride (h-BCN) and describes the latest advances in the application of h-BCN materials as semiconductor photocatalysts for sustainable photosynthesis, such as water splitting, reduction of CO₂, acceptorless dehydrogenation, oxidation of sp³ C-H bonds, and sp² C-H functionalization. h-BCN materials may have potential for applications in other organic transformations and industrial manufacture in the future.

Synthesis of polyimide-modified carbon nanotubes as catalyst for organic pollutant degradation via production of singlet oxygen with peroxymonosulfate without light irradiation

Polyimide-modified carbon nanotubes (PI/CNTs) were synthesized via a solvent-free thermal method and used as a metal-free catalyst to activate peroxymonosulfate for organic contaminant degradation without light irradiation. The characterization results suggested that PI was loaded onto the surface of CNTs. The catalytic ability of the PI/CNTs was strongly correlated with the content of PI in the catalysts. The PI/CNTs (22% of PI) showed the highest catalytic efficiency for organic pollutant degradation at room temperature. The degradation efficiency of acid orange 7 (AO7) dye was significantly enhanced to 98.9% within 15 min, compared to the efficiency of 2.2% exhibited by pure PI. The radical quenching tests and electron paramagnetic resonance spectrometry proved that singlet oxygen, instead of hydroxyl radicals or sulfate radicals, played a dominant role during the catalytic oxidation of AO7. The influences of operation parameters including temperature and catalyst amount were investigated. The PI/CNTs metal-free catalyst exhibited high catalytic activity under a broad range of pH values. The recycling study of four repeated reactions demonstrated good stability of the PI/CNTs. This work provided a promising metal-free catalyst for degradation of organic pollutants in aqueous solutions, contributing to the development of green materials for sustainable remediation.

Structurally Diverse Covalent Triazine-Based Framework Materials for Photocatalytic Hydrogen Evolution from Water

A structurally diverse family of 39 covalent triazine-based framework materials (CTFs) are synthesized by Suzuki-Miyaura polycondensation and tested as hydrogen evolution photocatalysts using a high-throughput workflow. The two best-performing CTFs are based on benzonitrile and dibenzo[b,d]thiophene sulfone linkers, respectively, with catalytic activities that are among the highest for this material class. The activities of the different CTFs are rationalized in terms of four variables: the predicted electron affinity, the predicted ionization potential, the optical gap, and the dispersibility of the CTFs particles in solution, as measured by optical transmittance. The electron affinity and dispersibility in solution are found to be the best predictors of photocatalytic hydrogen evolution activity.

Preparation of magnetic polyimide@ Mg-Fe layered double hydroxides core-shell composite for effective removal of various organic contaminants from aqueous solution

In this work, a novel core-shell structured magnetic polyimide@layered double oxides (LDO) composites coating a porous polyimide (PI)-coated Fe3O4 magnetic core and layered double hydroxide (LDH) has been successfully synthesized by solve-thermal synthesis and co-precipitation process. The magnetic PI@LDO composites were characterized by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), thermogravimetry analysis (TGA) and magnetic properties analysis. The composite materials displayed core-shell structure with flower-like morphology. The magnetic PI@LDO composites were applied to remove tetracycline (TC), 2,4-dichlorophenol (2,4-DCP) and glyphosate (GP) from aqueous solution. The action pH value was ranged from 5 to 9 for TC and GP and 3 to 7 for 2,4-DCP, respectively. Cl- showed a weak competitive adsorption effect to TC, 2, 4-DCP and GP. In addition, the presence of humic acid (HA) could slightly reduce the adsorption capacity of magnetic PI@LDO composites. The adsorption process could be well described by pseudo-second-order model for TC and GP, while pseudo-first-order model for 2,4-DCP. The experimental data of TC and 2,4-DCP could be fitted better with Freundlich model, while that of GP were fitted better with Langmuir model. The adsorptions of TC, 2,4-DCP and GP were both spontaneous and endothermic. The adsorption capacity decreased slightly after adsorption-desorption cycles repeated five times. This study demonstrated that magnetic PI@LDO exhibited great potential to be a mild and cost-effective adsorbent for the removal of various organic contaminants from wastewater.

Fabrication of a Perylene Tetracarboxylic Diimide-Graphitic Carbon Nitride Heterojunction Photocatalyst for Efficient Degradation of Aqueous Organic Pollutants

Metal-free g-C₃N₄ is a promising candidate for the next-generation visible light-responsive photocatalyst; however, high recombination probability of the photogenerated charge carriers on g-C₃N₄ limits its photocatalytic activity. To further increase the intrinsic photocatalytic activity of g-C₃N₄, here, perylene tetracarboxylic diimide-g-C₃N₄ (PDI/GCN) heterojunctions are prepared by one-step imidization reaction between perylene tetracarboxylic dianhydride (PTCDA) and g-C₃N₄ in aqueous solution. By the combination of various testing results, it is confirmed that the surface hybridization of PTCDA and g-C₃N₄ in the PDI/GCN heterojunctions via O═C-N-C═O covalent bonds occurs at lower PTCDA-to-g-C₃N₄ weight percentage. By selecting p-nitrophenol (PNP) and levofloxacin (LEV) as the target organic pollutants, the visible-light photocatalytic performance of the PDI/GCN heterojunctions is studied. It shows that the PDI/GCN heterojunction prepared at a PTCDA-to-g-C₃N₄ weight percentage of 1% exhibits remarkably higher visible-light photocatalytic degradation and mineralization ability toward aqueous target pollutants as compared with g-C₃N₄ and Degussa P25 TiO₂. On the basis of the experimental results including photoelectrochemistry, indirect chemical probe, and electron spin resonance spectroscopy, it is verified that the surface hybridization in the heterojunctions is responsible for this enhanced photocatalytic activity via accelerating the migration and separation of the photogenerated charge carriers, causing to produce more active species like ^•O₂^-, h_VB⁺, and ^•OH for deep oxidation of PNP or LEV to CO₂ and inorganic anions.

Computational high-throughput screening of polymeric photocatalysts: exploring the effect of composition, sequence isomerism and conformational degrees of freedom

We discuss a low-cost computational workflow for the high throughput screening of polymeric photocatalysts.

4,4′,4′′-Triaminotriphenylamine-based porous polyimide as a visible-light-driven photocatalyst

A novel polyimide photocatalyst was fabricated by a low-temperature condensation method and its photocatalytic mechanism was discussed.

Light-induced synthesis of triazine N-oxide-based cross-linked polymers for effective photocatalytic degradation of methyl orange

The polymeric aromatic N-oxides (LCPO-1 and LCPO-2) as organic metal-free photocatalysts have shown great potential in the photodegradation of methyl orange (MO) in solution.

Confinement effect of monolayer MoS2 quantum dots on conjugated polyimide and promotion of solar-driven photocatalytic hydrogen generation

Monolayer MoS₂ quantum dot (MQD) confined polyimide demonstrates 360% enhancement in hydrogen production compared to Pt/PI under solar light.

Preparation of two new polyimide bond linked porous covalent organic frameworks and their fluorescence sensing application for sensitive and selective determination of Fe3+

Sensitive turn-off mode fluorescence sensing for Fe³⁺based polyimide bond linked COFs.

A (001) dominated conjugated polymer with high-performance of hydrogen evolution under solar light irradiation

A self-organized polyimide supermolecule with high performance in photocatalytic hydrogen production (1640 μmol h⁻¹ g⁻¹).