Polymeric Carbon Research Articles

Unraveling the H2S selective oxidation in cobalt phosphate cluster loaded polymeric carbon nitride

H2S selective catalytic oxidation via photocatalysis is a low-cost and efficient approach. Herein, we modeled a (CoP)4 cluster loaded melon-based carbon nitride to represent experimental cobalt phosphate cocatalyst adsorption on polymeric carbon nitride for revealing the mechanism of H2S selective catalytic oxidation to SO2 via the density functional theory (DFT) calculations. Due to the hydrogen bond effect, the calculated results show that H2S selective oxidation prefers to occur through the quasi Mars–van Krevelen (quasi-MvK) mechanism rather than Langmuir-Hinshelwood (LH) mechanism according to the thermodynamic perspective, in which quasi-MvK mechanism exhibits a favorable limiting potential of 0.26 V. Overall, this work offers a basic understanding for microscopic mechanism of H2S catalytic oxidation.

In-situ one-step construction of poly(heptazine imide)/poly(triazine imide) heterojunctions for photocatalytic hydrogen evolution.

The construction of heterojunctions is challenging, requiring atomic-level contact and interface matching. Here, we have achieved atomic-level interfacial matching by constructing poly(heptazine imide)/poly(triazine imide) crystalline carbon nitride heterojunctions in an in-situ one-step method. The content of poly(triazine imide) in heterojunctions is positively related to the proportion of lithium chloride in potassium chloride and lithium chloride mixed-salts. The optimized heterojunction achieves an apparent quantum efficiency of 48.34 % for photocatalytic hydrogen production at 420 nm, which is at a good level in polymeric carbon nitride photocatalysts. The proposed ion-thermal assisted heterojunction construction strategy contributes to the development of polymeric carbon nitride photocatalysts with high crystallization and high charge separation efficiency.

Fabricating a 3D floating porous PDMS − Ag/AgBr decorated g-C3N4 nanocomposite sponge as a re-usable visible light photocatalyst

In this study, polymeric graphitic carbon nitride (g-C3N4) semiconductors was synthesized via a thermal condensation method. Subsequently, Ag/AgBr nanoparticles with varying ratios were decorated onto the g-C3N4 surface using the water/oil emulsion method. The resulting nanocomposites were characterized using XRD for phase identification and structural analysis, HR-TEM and SEM&EDAX for morphological structure, particle size, and elemental composition analysis, and XPS for investigating the chemical state and electronic structure. The impact of Ag/AgBr content on the optical properties of g-C3N4 were also studied such as (optical bandgap (Eg), refractive index (n), extinction coefficient (k), optical conductivity (σopt) and dielectric function (ε*)), Electrochemical impedance spectroscopy (EIS), PL spectroscopy and Chrono-amperometric investigations were conducted to assess the charge transfer capabilities and long-term durability of the prepared nanocomposites. The results revealed a reduction in Ag/AgBr particle size with an increase in g-C3N4 content, accompanied by a decrease in the optical bandgap from 2.444 eV to 2.393 eV. Furthermore, the nanocomposites exhibited enhanced degradation efficiencies of RhB dye, with the highest tested content of Ag/AgBr achieving 100% degradation after 120 min of irradiation. However, the challenge of catalyst separation after the degradation process remained. To address this issue, we developed a novel approach by impregnating Ag/AgBr@g-C3N4 photocatalyst onto a floating porous sponge using a simple sugar-template technique, offering potential as a reusable photocatalyst material. Furthermore, the 3D PDMS − Ag/AgBr@g-C3N4 photocatalyst was evaluated and found to maintain nearly the same photocatalytic efficiency for up to 5 consecutive cycles.

Facilitating charge separation by constructing CuInS2/PCN S-scheme heterojunction with the intimate contact interface for enhanced photocatalytic CO2 reduction

Photocatalytic CO2 conversion efficiency is still much lower than what is expected owing to the sluggish charge separation and transfer for many semiconductors. Herein, we fabricated a highly efficient S-scheme heterojunction by integrating the CuInS2 (CIS) with the oxygen-doping brown polymer carbon nitride (PCN). The construction of CIS/PCN S-scheme heterojunction promotes spatial separation of photogenerated charge while maintaining their strong reduction capability. The formed intimate contact interface between the CIS and PCN provides the strong driving force for the transfer of photogenerated charge, which accelerates the electrons rapidly migrating from PCN to CIS through the tight interface, resulting in more reductive electrons participating in photocatalytic reaction. As a result, the CIS/PCN S-scheme heterostructure shows a remarkably enhanced photocatalytic activity with a CO yield rate of up to 105.89 μmol g-1h−1, which is 7 times higher than that of the CIS. Combined density functional theory (DFT) calculations with experimental results demonstrate the formation of an intimate contact interface is not only more conducive to CO2 adsorption and activation but also lowers the reaction energy barrier of the conversion of CO2 to CO. Meanwhile, ESR characterization reveals the electron transfer pathway of CIS/PCN for photocatalytic CO2 conversion. This work may provide an illuminating insight into designing the S-scheme photocatalyst for enhanced CO2 photoreduction.

Bottom Deposition Enables Stable All-Solid-State Batteries with Ultrathin Lithium Metal Anode.

Modern strides in energy storage underscore the significance of all-solid-state batteries (ASSBs) predicated on solid electrolytes and lithium (Li) metal anodes in response to the demand for safer batteries. Nonetheless, ASSBs are often beleaguered by non-uniform Li deposition during cycling, leading to compromised cell performance from internal short circuits and hindered charge transfer. In this study, the concept of "bottom deposition" is introduced to stabilize metal deposition based on the lithiophilic current collector and a protective layer composed of a polymeric binder and carbon black. The bottom deposition, wherein Li plating ensues between the protective layer and the current collector, circumvents internal short circuits and facilitates uniform volumetric changes of Li. The prepared functional binder for the protective layer presents outstanding mechanical robustness and adhesive properties, which can withstand the volume expansion caused by metal growth. Furthermore, its excellent ion transfer properties promote uniform Li bottom deposition even under a current density of 6 mA·cm-2. Also, scanning electron microscopy analysis reveals a consistent plating/stripping morphology of Li after cycling. Consequently, the proposed system exhibits enhanced electrochemical performance when assessed within the ASSB framework, operating under a configuration marked by a high Li utilization rate reliant on an ultrathin Li.

The serine-threonine protein kinase Snf1 orchestrates the expression of plant cell wall-degrading enzymes and is required for full virulence of the maize pathogen Colletotrichum graminicola

Colletotrichum graminicola, the causal agent of maize leaf anthracnose and stalk rot, differentiates a pressurized infection cell called an appressorium in order to invade the epidermal cell, and subsequently forms biotrophic and necrotrophic hyphae to colonize the host tissue. While the role of force in appressorial penetration is established (Bechinger et al., 1999), the involvement of cell wall-degrading enzymes (CWDEs) in this process and in tissue colonization is poorly understood, due to the enormous number and functional redundancy of these enzymes. The serine/threonine protein kinase gene SNF1 identified in Sucrose Non-Fermenting yeast mutants mediates de-repression of catabolite-repressed genes, including many genes encoding CWDEs. In this study, we identified and functionally characterized the SNF1 homolog of C. graminicola. Δsnf1 mutants showed reduced vegetative growth and asexual sporulation rates on media containing polymeric carbon sources. Microscopy revealed reduced efficacies in appressorial penetration of cuticle and epidermal cell wall, and formation of unusual medusa-like biotrophic hyphae by Δsnf1 mutants. Severe and moderate virulence reductions were observed on intact and wounded leaves, respectively. Employing RNA-sequencing we show for the first time that more than 2,500 genes are directly or indirectly controlled by Snf1 in necrotrophic hyphae of a plant pathogenic fungus, many of which encode xylan- and cellulose-degrading enzymes. The data presented show that Snf1 is a global regulator of gene expression and is required for full virulence.

Construction of isotype heterojunctions in polymeric carbon nitride with thermal modulation and improved photocatalytic hydrogen production activity

Subtle structural changes in polymeric carbon nitrides (PCN) influence their photocatalytic activities. Herein, we present a strategy to construct isotype heterojunctions by thermal condensation of dicyandiamide as a single precursor. This avoids the complications that differences in the electronegativity of the coupled materials incur. Heterojunctions were created by depositing a carbon nitride layer processed at 500 °C over the carbon nitride processed at 600 °C utilizing structural defects and uncondensed moieties to form an interconnected structure. This enables the directional stacking of the PCN layers leading to changes in physicochemical properties and electronic band structure. The detailed characterization and testing revealed a type-II heterojunction configuration, whereby photoluminescence quenching measurements confirm longer exciton lifetimes and differences in Mott-Schottky flat band potential energies and low interfacial resistance facilitate mobility of charge carriers. Heterojunction materials exhibit high photocurrent generation and H2 production with visible light, and AQY surpasses 5%. Overall, efficient charge separation owing to the intrinsic electric field of closely related band offsets at the interface of the heterojunction materials enhances the photocatalytic response. The work highlights the importance of fine structural changes in improving the activity of polymeric photocatalytic systems.

Visible-Light Photocatalytic H2O2 Production Boosted by Frustrated Lewis Pairs in Defected Polymeric Carbon Nitride Nanosheets

Visible-Light Photocatalytic H₂O₂ Production Boosted by Frustrated Lewis Pairs in Defected Polymeric Carbon Nitride Nanosheets

Direct ink writing of polymer matrix composite with carbon for driving a flexible thermoelectric actuator of shape memory polymer

Carbon nanomaterials and polymer composites that possess excellent electrical and mechanical properties for soft robots have been investigated over decades in multidisciplinary research fields. As considering the incorporation of carbon into polymer composite, several major concerns include the electrical conductivity, elastic module, and manufacturing flexibility that can enable them to satisfy various functions such as actuation and sensing. In this paper, we report a comprehensive study on how to design and fabricate a soft gripper based on carbon polymer matrix composite and multilayer structure through multistep processes of 3D printing on paper. Using commercial conductive additives of graphene and carbon nanotube with polydimethylsiloxane (PDMS), a polymer matrix composite (PMC) was prepared for the ink of direct ink writing (DIW) with percolation conductivity. Additionally, a shape memory polymer (SMP) was utilized for fused deposition modeling (FDM) of a thermal actuator. Incorporating the DIW of PMC with the FDM of SMP on paper, a soft gripper with four fingers was designed and fabricated to show remarkable thermoelectrical actuation for grasping a 50 mm-diameter 10 g-weight spherical ball. In the future, it would provide an alternative approach for the fields of science and engineering, such as nanomaterials and nanotechnology, space applications, sustainable soft robots, and flexible autonomous systems.

Defect and nanostructure engineering of polymeric carbon nitride for visible-light-driven CO2 reduction

Sunlight-induced photocatalytic carbon dioxide (CO2) reduction to energy-rich chemicals by metal-free polymeric carbon nitride (CN) semiconductor is a promising tactic for sustained solar fuel production. However, the reaction efficiency of CO2 photoreduction is restrained seriously by the rapid recombination of photogenerated carriers on CN polymer. Herein, we incorporate 2-aminopyridine molecule with strong electron-withdrawing group into the skeleton edge of CN layers through a facile one-pot thermal polymerization strategy using urea as the precursor, which renders a modified carbon nitride (ACN) with extended optical harvesting, abundant nitrogen defects and ultrathin nanosheet structure. Consequently, the ACN photocatalyst with desirable structural features attains enhanced separation and migration of photoexcited charge carriers. Under visible light irradiation with Co(bpy)32+ as a cocatalyst, the optimized ACN sample manifests a high CO2 deoxygnative reduction activity and high stability, providing a CO yielding rate of 17 μmol h−1, which is significantly higher than that of pristine CN. The key intermediates engaged in CO2 photoreduction reaction are determined by the in situ diffuse reflectance infrared Fourier transform spectroscopy, which sponsors the construction of the possible photocatalytic CO2 reduction mechanism on ACN nanosheets.

Reinforcement of Cement Nanocomposites through Optimization of Mixing Ratio between Carbon Nanotube and Polymer Dispersing Agent.

Carbon nanotubes (CNTs), known for their exceptional mechanical, thermal, and electrical properties, are being explored as cement nanofillers in the construction field. However, due to the limited water dispersion of CNTs, polymer dispersing agents like polycarboxylate ether (PCE) and sulfonated naphthalene formaldehyde (SNF) are essential for uniform dispersion. In a previous study, PCE and SNF, common cement superplasticizers, effectively dispersed CNTs in cement nanocomposites. However, uncertainties remained regarding the extent to which all dispersing agents interacted efficiently with CNTs. Therefore, this research quantitatively assessed CNT interaction with dispersing agents through dispersion and centrifugation. Approximately 37% of PCE and 50% of SNF persisted compared to CNT after centrifugation. The resulting cement nanocomposites, with optimized mixing ratios, exhibited enhanced compressive strength of about 14% for CNT/PCE (78.13 MPa) and 12.3% for CNT/SNF (76.97 MPa) compared to plain cement (68.52 MPa). XRD results linked strength reinforcement to increased cement hydrate from optimized CNT dispersion. FE-SEM analysis revealed that CNTs were positioned within the pores of the cement. These optimized cement nanocomposites hold promise for improved safety in the construction industry.

Smartphone-assisted ratiometric fluorescence sensor for sensitive and portable α-glucosidase activity detection and inhibitor screening

α-Glucosidase (α-Glu) is an enzyme that plays an essential role in the digestion of carbohydrates, and its activity detection and inhibitor screening are crucial for the therapy of diseases and development of new drugs. In this study, α-Glu can catalyze the hydrolysis of α-arbutin to produce hydroquinone (HQ), and HQ can regulate the in-situ synthesis of polymer carbon dots (PCDs) with ethylenediamine (EDA). PCDs and tetraphenylporphyrin tetrasulphonic acid (TPPS) are separately designed as green and red fluorescent sensing units. With the increase of α-Glu concentration, the number of PCDs is gradually increased, resulting in enhancement of green fluorescence and quenching of red fluorescence. Conversely, when α-Glu inhibitors (AGIs) are present, the activity of α-Glu is inhibited, leading to weak green fluorescence and strong red fluorescence. Thus a ratiometric fluorescence sensor was designed for the determination of α-Glu activity and screening of AGIs. The developed ratiometric sensor exhibits a linear relationship between fluorescence intensity ratios and α-Glu concentrations (0.01 to 0.04 U/mL) with limit of detection of 0.184 mU/mL, which is much lower than the single fluorescence model. In addition, rapid and portable detection of α-Glu can be achieved using a smartphone with a color picking software installed as a signal detection device, which greatly reduces the cost and time of detection and provides a promising method for qualitative identification and quantitative analysis of α-Glu in the resource-limited areas. Moreover, the method is very promising for high-throughput screening AGIs from natural products.

Selective vanadium etching and in-situ formation of δ-Bi2O3 on m-BiVO4 with g-C3N4 nanosheets for photocatalytic degradation of antibiotic tetracycline

Antibiotics play a vital role in treating microbial illnesses, but their presence in water bodies is a global concern. Despite the potential of polymeric graphitic carbon nitrate (g-C3N4) as a photocatalyst for wastewater treatment, its effectiveness is hindered by a fast charge carrier recombination rate. To overcome this challenge, we have developed a novel approach involving the surface etching-oxidation technique to introduce δ-Bi2O3 onto m-BiVO4. Subsequently, the modified δ-Bi2O3/m-BiVO4 (BBV) was synergistically coupled with g-C3N4 (CN) to create a hybrid photocatalyst (BBVCN). The photocatalytic activity of BBVCN was evaluated using tetracycline hydrochloride (TC) as a model wastewater antibiotic pollutant, demonstrating a 92 % degradation of TC within a 1 h reaction time. Total organic carbon analysis demonstrated a TC removal efficiency of 76 %, indicating significant mineralization by BBVCN.

Ultra-thin carbon nitride activated periodate for efficient tetracycline degradation with the assistance of visible light

This study developed a novel activated periodate (PI, IO4−) system mediated by ultra-thin carbon nitride (UCN) and visible light (Vis), and investigated its efficiency and kinetics of tetracycline hydrochloride (TC) degradation in water. UCN/PI/Vis system could remove 96% TC within 16 min through the mixed radical/non-radical pathway dominated by IO3•, 2.3 times higher than that of polymerized carbon nitride (PCN)/PI/Vis system. This gap was attributed to UCN having a greater specific surface area, more active sites, and a shorter charge transfer path. The UCN/PI/Vis system has outstanding recyclability, attractive pH adaptability, and remarkable tolerance to co-existing substances and natural water bodies. The fascinating degradation efficiency was ascribed to the synergistic effect among UCN that produced photoelectrons, TC as an electron donor, and PI as an electron acceptor. The quantum confinement effect of the ultra-thin structure improved the band gap and enhanced the redox capacity of photogenerated carriers, which greatly improved the photocatalytic activation of PI by UCN.

Regulating *COOH intermediate via amino alkylation engineering for exceptionally effective photocatalytic CO2 reduction

Photocatalytic reduction of CO2 into fuel represents a promising approach for achieving carbon neutrality, while realizing high selectivity in this process is challenging due to uncontrollable reaction intermediate and retarded desorption of target products. Engineering the interface microenvironment of catalysts has been proposed as a strategy to exert a significant influence on reaction outcomes, yet it remains a significant challenge. In this study, amino alkylation was successfully integrated into the melem unit of polymeric carbon nitrides (PCN), which could efficiently drive the photocatalytic CO2 reduction. Experimental characterization and theoretical calculations revealed that the introduction of amino alkylation lowers the energy barrier for CO2 reduction into *COOH intermediate, transforming the adsorption of *COOH intermediate from the endothermic to an exothermic process. Notably, the as-prepared materials demonstrated outstanding performance in photocatalytic CO2 reduction, yielding CO at a rate of 152.8 μmol h−1 with a high selectivity of 95.4% and a quantum efficiency of 6.6%.

Biocidal polymer derived near white light-emitting polymeric carbon particles for antibacterial and bioimaging applications.

A growing antimicrobial crisis has increased demand for antimicrobial materials. It has become increasingly popular to convert polymeric macromolecules into polymeric carbon particles (PCP) in order to achieve highly biocompatible materials with unique properties as a result of the ability to synthesize nanomaterials of the right size and add value to existing stable polymers. This work presents the tuning of PCP for antibacterial application by combining a biocidal polymer with one-pot solvothermal synthesis. PCP displayed broad-spectrum antibacterial activity via various mechanisms, including inhibition of bacterial cell walls, ROS generation, and antibiotic resistance. Furthermore, these biocidal PCP were observed to show excitation-independent near-white light emission which on the other hand is generally possible due to mixed sizes, doping, and surface effects. As opposed to the parent biocidal polymer, PCP added ROS-mediated bactericidal activity, increased cytocompatibility, and nanofibers with anti-adhesive effects and potential of imaging bacterial cells.

Recyclable flexible materials with MOF-derived nanospheres for electromagnetic wave absorption

Self−healing and recyclable characteristics were beneficial for wave−absorbing materials to extend the service life, reduce the cost, stability and electromagnetic pollution in the practical application. The flexible composites with recyclable and electromagnetic wave (EMW) absorption were fabricated by employing MOF derived carbon nanoparticles (ZnCoNC) and polymers with dynamic boron ester bonds. The benzene structure of eugenol derived polybenzoxazine structure can stick on the surface of the MOF−derived nanoparticles by π−π interaction, which benefits the recyclable and mechanical properties. With the synergistic effect of dynamic boron ester bond and π−π interaction, the tensile strength of composites with 15 wt% ZnCoNC reached 7.88 MPa after 3 times recycling, it remained 88 % compared to origin composites. The minimum RL obtained is −36.6 dB at a thickness of 2 mm, it can approximately maintain the same effect in EMW absorption performance after recycling. This work was expected to broaden the EMW absorption application field and extend the service life of materials.

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor.

Photocatalytic hydrogen production from water is a promising way to fulfill energy demands and attain carbon emission reduction goals effectively. In this study, a loop photoreactor with a total volume of around 500 mL is presented for the photocatalytic hydrogen evolution using a Pt-loaded polymeric carbon nitride photocatalyst under 365 nm irradiation in the presence of sacrificial reducing agents. The fluid flow pattern of the developed photoreactor was characterized experimentally and the photon flux incident to the loop photoreactor was measured by chemical actinometry. The system displayed exceptional stability, with operation sustained over 70 hours. A design of experiment (DOE) analysis was used to systematically investigate the influence of key parameters - photon flux, photocatalyst loading, stirring speed, and inert gas flow rate - on the hydrogen generation rate. Linear relationships were found between hydrogen evolution rate and photon flux as well as inert gas flow rate. Photocatalyst loading and stirring speed also showed linear correlations, but could not be correctly described by DOE analysis. Instead, linear single parameter correlations could be applied. Notably, the loop photoreactor demonstrated an external photon efficiency up to 17 times higher than reported in literature studies, while scaling the reactor size by a factor of 10.

Cross-Coupling Reactions Catalyzed by Regularly Spaced Copper Atom Pairs on Polymeric Carbon Nitride

Cross-Coupling Reactions Catalyzed by Regularly Spaced Copper Atom Pairs on Polymeric Carbon Nitride

Hollow core mesoporous carbon spheres as catalyst support for improved platinum utilization in phosphoric acid fuel cells

Using a well-known sol-gel technique, monodispersed silica spheres measuring 380 nm in size are generated in situ. These silica spheres serve as a template for the synthesis of hollow core mesoporous shell (HCMS) carbon spheres. Inside the pores of the template, a polymer is synthesized using azoisobutyronitrile and divinylbenzene polymerization route. Polymer carbonization followed by template remotion yielded HCMS carbon spheres. This HCMS carbon is mesoporous and offers uniform Pt crystallite distribution for acid fuel cell applications. As-prepared HCMS carbon is examined by field emission gun SEM, TEM, nitrogen adsorption/desorption isotherm (BET surface area and BJH pore size distribution analysis), and apparent density using Helium pycnometry. The HCMS carbon obtained demonstrates a BET surface area of 623 m2g-1, showcasing a uniform pore size distribution centered at 3.8 nm. This specific characteristic renders it an ideal support material for fuel cell catalysts. The electrochemical studies reveal the key parameters like corrosion resistance, bulk electrical conductivity, the electrochemical surface area of Pt chemically deposited on HCMS carbon, and unit fuel cell performance under phosphoric acid environment. These parameters are compared with the standard carbon powder, Vulcan XC72R and a commercial catalyst to evaluate the HCMS carbons’ suitability for fuel cell applications.