Development of High-Performance Iron-Based Phosphate Cathodes toward Practical Na-Ion Batteries.

Iron-based phosphate cathode of Na4Fe3(PO4)2(P2O7) has been regarded as a low-cost and structurally stable cathode material for Na-ion batteries (NIBs). However, their practical application is greatly hindered by the insufficient electrochemical performance and limited energy density. Here, we report a new iron-based phosphate cathode of Na4.5Fe3.5(PO4)2.5(P2O7) with the intergrown heterostructure of the maricite-type NaFePO4 and orthorhombic Na4Fe3(PO4)2(P2O7) phases at a mole ratio of 0.5:1. Benefited from the increased composition ratio and the spontaneous activation of the maricite-type NaFePO4 phase, the as-prepared Na4.5Fe3.5(PO4)2.5(P2O7) composites deliver a reversible capacity over 130 mA h g-1 and energy density close to 400 W h kg-1, which is far beyond that of the single-phase Na4Fe3(PO4)2(P2O7) cathode (∼120 mA h g-1 and ∼350 W h kg-1). Moreover, the kg-level products from the scale-up synthesis demonstrate a stable cycling performance over 2000 times at 3 C in pouch cells. We believe that our findings could show the way forward the practical application of the iron-based phosphate cathodes for NIBs.

Clinical development of MRI-based multi-sequence multi-regional radiomics model to predict lymph node metastasis in rectal cancer.

OBJECTIVE: We aim to construct a magnetic resonance imaging (MRI)-based multi-sequence multi-regional radiomics model that will improve the preoperative prediction ability of lymph node metastasis (LNM) in T3 rectal cancer. METHODS: Multi-sequence MRI data from 190 patients with T3 rectal cancer were retrospectively analyzed, with 94 patients in the LNM group and 96 patients in the non-LNM group. The clinical factors, subjective imaging features, and the radiomic features of tumor and peritumoral mesorectum region of patients were extracted from T2WI and ADC images. Spearman's rank correlation coefficient, Mann-Whitney's U test, and the least absolute shrinkage and selection operator were used for feature selection and dimensionality reduction. Logistic regression was used to construct six models. The predictive performance of each model was evaluated by the receiver operating characteristic curve (ROC). The differences of each model were characterized by area under the curve (AUC) via the DeLong test. RESULTS: The AUCs of T2WI, ADC single-sequence radiomics model and multi-sequence radiomics model were 0.73, 0.75, and 0.78, respectively. The multi-sequence multi-regional radiomics model with improved performance was created by combining the radiomics characteristics of the peritumoral mesorectum region with the multi-sequence radiomics model (AUC, 0.87; p < 0.01). The AUC of the clinical model was 0.68, and the MRI-clinical composite evaluation model was obtained by incorporating the clinical data with the multi-sequence multi-regional radiomics features, with an AUC of 0.89. CONCLUSION: The MRI-based multi-sequence multi-regional radiomics model significantly improved the prediction ability of LNM for T3 rectal cancer and could be applied to guide surgical decision-making in patients with T3 rectal cancer.

Phase Change Study of a New Two-Phase Absorbent Based on DAP.

In order to overcome the drawbacks of conventional absorbents, which exhibit slow absorption rates and low absorption loads, this study suggests enhancing the absorbent system for CO2 absorption by incorporating a nonaqueous solvent into 1,3-propanediamine (DAP) and tetramethylethylenediamine (TMEDA), resulting in a two-phase system. The mechanism of solvent absorption of CO2 was investigated using nuclear magnetic resonance (NMR) carbon spectroscopy. By comparing the absorption load, fraction ratio, and viscosity of different absorbents after absorbing carbon dioxide, the two-phase absorbents with good performance were selected. The poor water absorbent consisting of the DAP/TMEDA system exhibited an absorption load of 3.8 mol/kg, surpassing that of the conventional 30% ethanolamine solution. A nonaqueous solvent is added to the system to replace some of the water to reduce the fraction. After adding different nonaqueous solvents, the phase separation system was screened after 2 h of CO2 absorption. The system with good performance was tested for the absorption of the solution under different amine concentration and water concentration tests. It is found that the absorption load of the DAP/TMEDA/diglyme system is 3.2 mol/kg, but the fraction can be reduced to 38%. The significant reduction in rich phase volume is beneficial for reducing the size and cost of regeneration tower. According to NMR detection and quantum chemical calculations, it was found that DAP/TMEDA absorbs carbon dioxide to form carbamate. DAP acts as the main absorbent, while TMEDA and nonaqueous solvents do not participate in the absorption reaction. Nonaqueous solvents were found to accelerate the solution phase separation due to the salt precipitation reaction.

Reforestation of Cunninghamia lanceolata changes the relative abundances of important prokaryotic families in soil.

Over the past decades, many forests have been converted to monoculture plantations, which might affect the soil microbial communities that are responsible for governing the soil biogeochemical processes. Understanding how reforestation efforts alter soil prokaryotic microbial communities will therefore inform forest management. In this study, the prokaryotic communities were comparatively investigated in a secondary Chinese fir forest (original) and a reforested Chinese fir plantation (reforested from a secondary Chinese fir forest) in Southern China. The results showed that reforestation changed the structure of the prokaryotic community: the relative abundances of important prokaryotic families in soil. This might be caused by the altered soil pH and organic matter content after reforestation. Soil profile layer depth was an important factor as the upper layers had a higher diversity of prokaryotes than the lower ones (p < 0.05). The composition of the prokaryotic community presented a seasonality characteristic. In addition, the results showed that the dominant phylum was Acidobacteria (58.86%) with Koribacteraceae (15.38%) as the dominant family in the secondary Chinese fir forest and the reforested plantation. Furthermore, soil organic matter, total N, hydrolyzable N, and NH4+-N were positively correlated with prokaryotic diversity (p < 0.05). Also, organic matter and NO3--N were positively correlated to prokaryotic abundance (p < 0.05). This study demonstrated that re-forest transformation altered soil properties, which lead to the changes in microbial composition. The changes in microbial community might in turn influence biogeochemical processes and the environmental variables. The study could contribute to forest management and policy-making.

Development of injectable in situ hydrogels based on hyaluronic acid via Diels-Alder reaction for their antitumor activities studies.

The objective of this study was to develop an injectable hydrogel based on furfuryl amine-conjugated hyaluronic acid (FA-conj-HA) and evaluate the in vivo anti-4 T1 tumor activity of doxorubicin-loaded hydrogel (DOX@FA-conj-HAgel). The cargo-free hydrogel (FA-conj-HAgel) was fabricated through a Diels-Alder reaction at 37 °C with FA-conj-HA as a gel material and four armed poly(ethylene glycol)2000-maleimide (4-arm-PEG2000-Mal) as a cross-linker. The bio-safety of FA-conj-HAgel were assessed, and the in vivo antitumor activity of DOX@FA-conj-HAgel was also investigated. Many 3D network structures were observed from scanning electron microscope (SEM) photograph, confirming the successful preparation of FA-conj-HAgel. The absence of cytotoxicity from FA-conj-HAgel was proved by the high viability of 4 T1 cells. In vivo bio-safety studies suggested that the obtained FA-conj-HAgel did not induce acute toxicity or other lesions in treated mice, confirming its high bio-safety. The reduced tumor volumes, hematoxylin-eosin staining (H&E), and TdT-mediated dUTP-biotin nick end labeling (TUNEL) analysis indicated the potent in vivo anti-4 T1 tumor effects of DOX@FA-conj-HAgel. In conclusion, the favorable bio-safety and potent antitumor activity of DOX@FA-conj-HAgel highlighted its potential application in oncological therapy.

Structure-Property Relationships for the Electronic Applications of Bis-Adduct Isomers of Phenyl-C61 Butyric Acid Methyl Ester.

Higher adducts of a fullerene, such as the bis-adduct of PCBM (bis-PCBM), can be used to achieve shallower molecular orbital energy levels than, for example, PCBM or C60. Substituting the bis-adduct for the parent fullerene is useful to increase the open-circuit voltage of organic solar cells or achieve better energy alignment as electron transport layers in, for example, perovskite solar cells. However, bis-PCBM is usually synthesized as a mixture of structural isomers, which can lead to both energetic and morphological disorder, negatively affecting device performance. Here, we present a comprehensive study on the molecular properties of 19 pure bis-isomers of PCBM using a variety of characterization methods, including ultraviolet photoelectron spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, single crystal structure, and (time-dependent) density functional theory calculation. We find that the lowest unoccupied molecular orbital of such bis-isomers can be tuned to be up to 170 meV shallower than PCBM and up to 100 meV shallower than the mixture of unseparated isomers. The isolated bis-isomers also show an electron mobility in organic field-effect transistors of up to 4.5 × 10-2 cm2/(V s), which is an order of magnitude higher than that of the mixture of bis-isomers. These properties enable the fabrication of the highest performing bis-PCBM organic solar cell to date, with the best device showing a power conversion efficiency of 7.2%. Interestingly, we find that the crystallinity of bis-isomers correlates negatively with electron mobility and organic solar cell device performance, which we relate to their molecular symmetry, with a lower symmetry leading to more amorphous bis-isomers, less energetic disorder, and higher dimensional electron transport. This work demonstrates the potential of side chain engineering for optimizing the performance of fullerene-based organic electronic devices.

A novel self-assembled nanoplatform based on retrofitting poloxamer 188 for triple-negative breast cancer targeting treatment.

Poloxamer 188 is a widely used pharmaceutical excipient, which can be found in a variety of drug formulations. In this study, a novel self-assembled nanoplatform was developed for active targeting of folate receptor-overexpressing triple-negative breast cancer. This platform, FPP NPs, was prepared by the retrofitted poloxamer 188 derivatives, resulting in nanoparticles with an appropriate size (< 100 nm), good stability, and satisfactory biocompatibility. Cellular uptake and in vivo distribution studies showed that the FPP NPs had strong tumor cell uptake and active targeting capabilities. Furthermore, docetaxel (DTX) was loaded into FPP NPs in this research. The resulting DTX/FPP NPs exhibited high drug encapsulation efficiency and drug loading capacity, and could rapidly release DTX under slightly acidic conditions, significantly increasing the antitumor activity of the encapsulated drug both in vitro and in vivo. In addition, DTX/FPP NPs could significantly decrease the hepatotoxicity and nephrotoxicity of DTX. Therefore, this drug delivery nanoplatform, based on retrofitted poloxamer 188 with self-assembly properties in aqueous solution and active targeting capabilities to tumors, may provide a promising approach for targeted treatment of triple-negative breast cancer.

Synthesis of the pH-sensitive nanoparticles based on the acylhydrazone bonds conjugated doxorubicin and studies on their in vivo anti-tumor effects.

The purpose of this study was to synthesize DHPD polymers through the conjugation of doxorubicin (DOX) molecules onto poly(ethylene glycol) (PEG) chains via acylhydrazone bonds, and to fabricate pH-responsive DHPD nanoparticles (NPs) for investigation of their biosecurity and in vivo anti-tumor activity. The morphology, size distribution, stability, pH-responsiveness, biosecurity, and in vivo anti-tumor effects of the DHPD NPs were evaluated. Characterization of the DHPD polymers using 1H NMR, FTIR, and Raman spectra confirmed their successful synthesis. The DHPD NPs exhibited a round morphology with an average diameter of 144.4 ± 1.7 nm and a polydispersity index (PDI) of 0.23 ± 0.02. Biosecurity studies indicated that the DHPD NPs were non-toxic to treated mice, and in vitro cell tests demonstrated their ability to be taken up by 4T1 cells. Under the acidic microenvironment of 4T1 cells, the acylhydrazone bonds were cleaved, resulting in increased DOX delivery to tumor cells and improved in vivo anti-tumor effects. Animal experiments confirmed that the DHPD NPs reduced DOX toxicity while enhancing its anti-tumor activity. Furthermore, results from the analysis of γ-interferon (INF-γ), tumor necrosis factor-α (TNF-α), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF) indicated that the DHPD NPs improved the anti-4T1 tumor effect of DOX, suggesting their potential application in the treatment of breast cancer.

Responsive photonic hydrogel for colorimetric detection of formaldehyde.

Formaldehyde (FA) can damage DNA, cause liver and kidney dysfunction, and ultimately lead to malignant tumors. Therefore, it is essential to develop a method that can conveniently detect FA with high detection sensitivity. Here, a responsive photonic hydrogel was prepared by embedding three-dimensional photonic crystal (PC) into amino-functionalized hydrogel to construct a colorimetric sensing film for FA. The amino groups on the polymer chains of the photonic hydrogel reacts with FA to increase the crosslinking density of the hydrogel, resulting in its volume shrinkage and a decrease in microsphere spacing of the PC. That causes the reflectance spectra blue-shift of more than 160 nm and color change from red to cyan for the optimized photonic hydrogel, achieving the sensitive, selective and colorimetric detection of FA. The constructed photonic hydrogel shows good accuracy and reliability for practical determination of FA in air and aquatic products, providing a new strategy for designing other target analytes responsive photonic hydrogels.

Application of Bis-Adducts of Phenyl-C61 Butyric Acid Methyl Ester in Promoting the Open-Circuit Voltage of Indoor Organic Photovoltaics.

Fullerene-based indoor OPVs, particularly phenyl-C61 butyric acid methyl ester (PCBM), has been regarded as a prospective harvesting indoor light energy source to drive low-power consumption electronic devices such as sensors and IoTs. Due to the low tunability of its inherently spherical structure, the performance of the fullerene-based indoor OPVs seem to hit a bottleneck compared with the non-fullerene materials. Here, we explore the potential application of fullerene derivative bis-PCBM in indoor OPVs, which owns a higher the lowest unoccupied molecular orbital (LUMO) level than PCBM. The results show that when blended with PCDTBT, bis-PCBM devices yield a high VOC of up to 1.05 V and 0.9 V under AM 1.5G illumination and 1000 lx indoor light, compared with the corresponding values of 0.93 V and 0.79 V for PCBM devices. Nevertheless, the disorders in bis-PCBM suppress the JSC and FF and, therefore, result in a lower efficiency compared to PCBM devices. However, the efficiency and stability differences between the two kinds of cells were much reduced under indoor light conditions. After further optimization of the material composition and fabrication process, bis-PCBM could be an alternative to PCBM, offering great potential for indoor OPV with high performance.

Conversion of Surface Residual Alkali to Solid Electrolyte to Enable Na-Ion Full Cells with Robust Interfaces.

The deposition of volatilized Na+ on the surface of the cathode during sintering results in the formation of surface residual alkali (NaOH/Na2 CO3 NaHCO3 ) in layered cathode materials, leading to serious interfacial reactions and performance degradation. This phenomenon is particularly evident in O3-NaNi0.4 Cu0.1 Mn0.4 Ti0.1 O2 (NCMT). In this study, a strategy is proposed to transform waste into treasure by converting residual alkali into a solid electrolyte. Mg(CH3 COO)2 and H3 PO4 are reacted with surface residual alkali to generate the solid electrolyte NaMgPO4 on the surface of NCMT, which can be labeled as NaMgPO4@NaNi0.4 Cu0.1 Mn0.4 Ti0.1 O2 -X (NMP@NCMT-X, where X indicates the different amounts of Mg2+ and PO4 3- ). NaMgPO4 acts as a special ionic conductivity channel on the surface to improve the kinetics of the electrode reactions, remarkably improving the rate capability of the modified cathode at a high current density in the half-cell. Additionally, NMP@NCMT-2 enables a reversible phase transition from the P3 to OP2 phase in the charge-discharge process above 4.2 V and achieves a high specific capacity of 157.3 mAh g-1 and outstanding capacity retention in the full cell. The strategy can effectively and reliably stabilize the interface and improve the performance of layered cathodes for Na-ion batteries (NIBs).

A "turn-on" inverse opal photonic crystal fluorescent sensing film for detection of cysteine and its bioimaging of living cells.

A "turn-on" inverse opal photonic crystal fluorescent sensing film infiltrated with a coumarin derivative is reported for the reliable and accurate detection of cysteine in human serum and fluorescence imaging of living cells. The coumarin derivative containing allyl ester specifically reacts with cysteine by ammonolysis to generate a fluorescent product whose emission wavelength is at ~ 535 nm, providing a selective fluorescence detection for cysteine. The emitted fluorescence is significantly enhanced due to the slow photon effect derived from the photonic crystal film. This is because the emission wavelength is overlapped with the blue-band edge of the photonic stopband of the selected inverse opal film. The fluorescence enhancement effect endows the prepared inverse opal film with highly sensitive detection with a limit of detection of 3.23 × 10-9 mol/L and a wide linear detection range of 1 × 10-7 - 1 × 10-3 mol/L. A fast response within 30 s toward cysteine is also achieved due to the three-dimensional interconnected macroporous structure with a high-specific surface area of the inverse opal film. The prepared inverse opal fluorescent sensing film has been successfully applied to the detection of cysteine in human serum and bioimaging of living cells. In the diluted human serum, the recoveries for the detection of cysteine were 97.92 - 107.20%, and the relative standard deviations were 2.61-9.04%, demonstrating the potential applicability of the inverse opal fluorescent sensing film to real sample analysis. The method may provide a universal strategy for constructing various photonic crystal fluorescent sensing films by using different fluorescent probes.

Targeted delivery of doxorubicin into tumor cells to decrease the in vivo toxicity of glutathione-sensitive prodrug-poloxamer188-b-polycaprolactone nanoparticles and improve their anti-tumor activities.

Doxorubicin (DOX) is widely used in the treatment of many tumors, but the dose-dependent toxicity limits its further application. In this study, a unique strategy was developed to improve the anti-tumor effects of free DOX and lower its in vivo toxicity by constructing novel glutathione (GSH)-sensitive poloxamer188-b-polycaprolactone-S-S-doxorubicin nanoparticles (PPSSD NPs). After uptake by tumor cells, the disulfide bonds in the PPSSD NPs would be cloven by reacting with GSH. Then, a lethal dose of DOX was released in tumor cells. The uptake of PPSSD NPs by 4T1 cells was proved using fluorescence microscopy by co-localization of PPSSD NPs and 4', 6-diamidino-2-phenylindole (DAPI). Cell tests suggested that the PPSSD NPs showed high anti-tumor cells (4T1) activity but low cytotoxicity against normal cells (293 t). The in vivo toxicity and anti-tumor effects of the PPSSD NPs were studied with Kunming and Balb/c mice as models, respectively. The H&E slices, blood routine and biochemistry indexes of the PPSSD NPs treated mice indicated that the PPSSD NPs did not induce obvious in vivo toxicity. The PPSSD NPs showed higher in vitro anti-4T1 cells activity than free DOX. Furthermore, the in vivo anti-tumor study, TUNEL and H&E slices suggested that the PPSSD NPs exhibited excellent anti-tumor effects. In a word, the novel PPSSD NPs did not only improve the anti-tumor effect of DOX, but also decrease its cytotoxicity to normal tissues.

Drought-responsive WRKY transcription factor genes IgWRKY50 and IgWRKY32 from Iris germanica enhance drought resistance in transgenic Arabidopsis.

Drought greatly affects the growth and development of garden plants and affects their ornamental value. WRKY transcription factors make up one of the largest transcription factor families in plants and they play an important role in the plant response to drought stress. However, the function of the WRKY gene in response to drought stress in Iris germanica, which is commonly used in landscaping, has not been studied. In this study, we isolated two WRKY transcription factor genes from Iris germanica, IgWRKY50 and IgWRKY32, which belong to Group II and Group III of the WRKY family, respectively. IgWRKY50 and IgWRKY32 could be induced by PEG-6000, high temperature and ABA in Iris germanica. IgWRKY50 and IgWRKY32 could quickly respond to drought and they peaked at 3 h after PEG-6000 treatment (19.93- and 23.32-fold). The fusion proteins IgWRKY50-GFP and IgWRKY32-GFP were located in the nucleus of mesophyll protoplasts of Arabidopsis. The overexpression of the IgWRKY50 and IgWRKY32 genes improved the osmotic tolerance of transgenic Arabidopsis, mainly exhibited by the transgenic plants having a higher germination rate and a longer total root length on 1/2 MS medium containing mannitol. Under PEG-6000 stress, the transgenic plants had higher stomatal closure than the wild type (WT). Under natural drought stress, the water loss rate of the isolated leaves of transgenic Arabidopsis was lower than that of WT, the contents of proline (Pro) and soluble protein (SP) and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in the transgenic plants were higher, but the content of malondialdehyde (MDA) was lower. Furthermore, the expression of several stress-related genes (RD29A, DREB2A, PP2CA, and ABA2) was significantly increased in IgWRKY50- and IgWRKY32- overexpressing transgenic Arabidposis plants after drought treatment. These results suggest that IgWRKY50 and IgWRKY32, as two positive regulators, enhance the drought resistance of transgenic Arabidopsis by mediating the ABA signal transduction pathway. IgWRKY50 and IgWRKY32 can be used as candidate genes for molecular breeding of drought resistance in Iris.

Identifying structure-absorption relationships and predicting absorption strength of non-fullerene acceptors for organic photovoltaics.

Non-fullerene acceptors (NFAs) are excellent light harvesters, yet the origin of their high optical extinction is not well understood. In this work, we investigate the absorption strength of NFAs by building a database of time-dependent density functional theory (TDDFT) calculations of ∼500 π-conjugated molecules. The calculations are first validated by comparison with experimental measurements in solution and solid state using common fullerene and non-fullerene acceptors. We find that the molar extinction coefficient (ε d,max) shows reasonable agreement between calculation in vacuum and experiment for molecules in solution, highlighting the effectiveness of TDDFT for predicting optical properties of organic π-conjugated molecules. We then perform a statistical analysis based on molecular descriptors to identify which features are important in defining the absorption strength. This allows us to identify structural features that are correlated with high absorption strength in NFAs and could be used to guide molecular design: highly absorbing NFAs should possess a planar, linear, and fully conjugated molecular backbone with highly polarisable heteroatoms. We then exploit a random decision forest algorithm to draw predictions for ε d,max using a computational framework based on extended tight-binding Hamiltonians, which shows reasonable predicting accuracy with lower computational cost than TDDFT. This work provides a general understanding of the relationship between molecular structure and absorption strength in π-conjugated organic molecules, including NFAs, while introducing predictive machine-learning models of low computational cost.

Multi-Factors Cooperatively Actuated Photonic Hydrogel Aptasensors for Facile, Label-Free and Colorimetric Detection of Lysozyme.

Responsive two-dimensional photonic crystal (2DPC) hydrogels have been widely used as smart sensing materials for constructing various optical sensors to accurately detect different target analytes. Herein, we report photonic hydrogel aptasensors based on aptamer-functionalized 2DPC poly(acrylamide-acrylic acid-N-tert-butyl acrylamide) hydrogels for facile, label-free and colorimetric detection of lysozyme in human serum. The constructed photonic hydrogel aptasensors undergo shrinkage upon exposure to lysozyme solution through multi-factors cooperative actuation. Here, the specific binding between the aptamer and lysozyme, and the simultaneous interactions between carboxyl anions and N-tert-butyl groups with lysozyme, increase the cross-linking density of the hydrogel, leading to its shrinkage. The aptasensors' shrinkage decreases the particle spacing of the 2DPC embedded in the hydrogel network. It can be simply monitored by measuring the Debye diffraction ring of the photonic hydrogel aptasensors using a laser pointer and a ruler without needing sophisticated apparatus. The significant shrinkage of the aptasensors can be observed by the naked eye via the hydrogel size and color change. The aptasensors show good sensitivity with a limit of detection of 1.8 nM, high selectivity and anti-interference for the detection of lysozyme. The photonic hydrogel aptasensors have been successfully used to accurately determine the concentration of lysozyme in human serum. Therefore, novel photonic hydrogel aptasensors can be constructed by designing functional monomers and aptamers that can specifically bind target analytes.

Restrictive Regulation of Ionic Liquid Quaternary Ammonium Salt in SBA-15 Pore Channel for Efficient Carbon Dioxide Conversion.

Herein, the synthesis of a new type of catalyst, SBA-M (Schiff complex of different metal types grafted on SBA-15) based on a quaternization reaction, is described. Various amounts of ionic liquid were grafted into the pore channels of SBA-15 using the post-grafting method, which allowed the ionic liquid to be grafted into the pore channels restrictively. Notably, over six cycles, SBA-Mn (0.2) has been shown to maintain its catalytic activity and stability. In addition, a reaction mechanism for the cycloaddition of CO2 with epoxides based on density-functional theory is proposed. The cycloaddition reaction of CO2 and epoxides is an efficient way of carbon fixation. It is demonstrated that the metal coordinated with the oxygen atom of the epoxides and that a halogen attacked the carbon of epoxides. Moreover, theoretical calculations and synthesis strategy provide a new approach for CO2 conversion.

Effect of nitrogen functional groups on competitive adsorption between toluene and water vapor onto nitrogen-doped spherical resorcinol-formaldehyde resin-based activated carbon.

To elucidate the effect of nitrogen functional groups on the competitive adsorption of toluene and water vapor, a series of N-doped resorcinol-formaldehyde resin-based activated carbons using g-C3N4 as the nitrogen source were prepared, which possessed different N contents (1.29-6.14%). The competitive adsorption characteristics and mechanisms were investigated by characterizations, dynamic adsorption experiments, adsorption isotherms, and density functional theory calculations. Results showed that the normalized toluene adsorption capacity under 50 RH% was consistent with the N content, revealing that nitrogen functional groups can enhance the competitive adsorption for toluene under a humid atmosphere. Adsorption isotherms analysis suggested that nitrogen functional groups can not only accelerate the adsorption of toluene but also improve the hydrophobicity of carbon surface. Competitive adsorption mechanisms were ascribed to π-π interactions and electrostatic interactions. Specifically, graphitic-N and pyridinic-N enhance competitive adsorption for toluene through reinforced π-π interactions with toluene and weakened electrostatic interactions with water molecule. However, pyrrolic-N improve the competitive adsorption, which is principally attributed to enhanced π-π interactions with toluene. Furthermore, it was found that the reusability of activated carbon could be improved by nitrogen functional groups. This study provides theoretical hints to develop volatile organic compound adsorbents in the presence of water vapor.