摘要 : Atomically dispersed tungsten-nitrogen-carbon with W−N 4 sites acts as a highly efficient catalyst for oxygen reactions. However, the symmetrical charge distribution of W−N 4 sites results in strong binding with oxygen-containing intermediates, leading to unsatisfactory catalytic activities. Here, an axially coordinated sulfur (S) atom is integrated into the atomically dispersed W−N 4 site and anchored onto multi-walled carbon nanotubes (S 1 −W 1 N 4 −MWCNTs) for oxygen reduction/oxygen evolution reactions (ORR/OER). The axial S atom, with significantly different electronegativity and outer electronic structure compared to nitrogen atom, induces localized charge redistribution around W−N 4 site. This change optimizes the adsorption/desorption capabilities of oxygen-containing intermediates on W−N 4 site, thereby enhancing the overall oxygen reaction activities. The S 1 −W 1 N 4 −MWCNTs demonstrates excellent ORR/OER activity with the half-wave potential of 0.916 V for ORR and the potential of 1.644 V (at 10 mA cm −2 ) for OER. At −20 °C, S 1 −W 1 N 4 −MWCNTs-based zinc-air batteries demonstrate increased specific capacity and an extended charging-discharging cycle life of 420 h, surpassing performance at room temperature. Regulating the charge distribution of W−N 4 sites with axial S atoms provides an effective strategy to boost the oxygen reaction activities of tungsten-nitrogen-carbon catalysts.

摘要 : Nickel hydroxide (Ni(OH)2) is recognized as a promising material for electrodes in supercapacitors owing to its exceptional theoretical specific capacitance. However, Ni(OH)2 has several drawbacks, including a short cycle life, susceptibility to volume expansion, and poor electrical conductivity. In this work, Ni(OH)2 nanosheets anchored on layered g-C3N4/C (Ni(OH)2–g–C3N4/C) are designed by biological template induction and a hydrothermal method. Ni(OH)2–g–C3N4/C has unique petal-like structures, which can provide a vertical charge transport channel to increase reaction potential of the material during the charge–discharge process. The introduction of biomass carbon can solve the problem of the bulk phase accumulation of g-C3N4 and can also improve the overall conductivity of the composite. Compared to Ni(OH)2 (522 F g−1), g-C3N4/C (76.2 F g−1), and g-C3N4 (16 F g−1), the Ni(OH)2–g–C3N4/C-0.75 (NGC-0.75) composite exhibits the highest specific capacitance of 1034 F g−1 at 1 A g−1. Furthermore, after 5000 cycles at 5 A g−1, the capacitance of the material is maintained at 85.97%. Meanwhile, the asymmetric supercapacitor based on the NGC-0.75 shows a high energy density of 18.29 Wh kg−1 at the power density of 400.02 W kg−1 with excellent cyclic stability of 127.45% over 10 000 cycles.

摘要 : Graphite phase carbon nitride (g-C3N4), a polymer semiconductor with a typical two-dimensional layered structure and narrow band gap, has excellent visible light absorption capacity, stable physical and chemical properties and good photocatalytic properties. However, the structure of g-C3N4 produced by the heat-induced polymerization from traditional nitrogen-containing precursor is incomplete. The main body is melon-based carbon nitride with amorphous or semi-crystalline structure. There are many defects in its phase and surface, which lead to lower conductivity, higher electron-hole pairs recombination rate, resulting in lower catalytic activity. Therefore, it is necessary to improve the crystallinity of g-C3N4. This paper mainly summarizes the advantages of high crystalline carbon nitride (CCN) and the research progress in recent years. Increasing the crystallinity of g-C3N4 can provide charge transfer channels between the conjugated planes to improve the charge transfer efficiency, and also introduce other modification methods to achieve efficient synergies. Then, the structure, characterization, preparation, modification strategy and application fields of CCN in recent years were reviewed. Finally, the challenges and future development directions of CCN photocatalysts are summarized briefly.

摘要 : Norovirus (NoV) stands as the prevailing etiological agent behind childhood gastroenteritis and foodborne illness, garnering significant attention due to its high infectivity pathogenicity. Protruding domain within the capsid protein (VP1) emerges as the primary antigenicity determinant and a hypervariable region, presenting a potential target site for detecting NoV infection. Herein, a label-free photoelectrochemical (PEC) immunosensor was proposed to achieve high sensitivity toward VP1, utilizing Co-Corrole sensitized carbon nitride (Co-Corrole/CN). Co-Corrole combines with CN through covalent bonds, and the strong binding effect accelerates the directional transport of electrons from CN to Co-Corrole. Co-Corrole acts as a photosensitizer, enhancing light harvesting in the visible region. The well-defined interfacial contact in Co-Corrole/CN heterojunction facilitates the electron-hole pairs separation and transfer. The strong light utilization and efficient carrier migration improve the PEC performance to amplify the photocurrent. This developed immunosensor platform demonstrated a wide range (0.75 pg mL –1 -150 ng mL –1 ) with a notably low limit of detection (0.25 pg mL –1 ), exhibiting excellent stability and selectivity for other viruses. Moreover, this sensor detected clinical samples with remarkable accuracy and practicability. This research develops a facile and label-free diagnostic analytical technology for highly sensitive detection of NoV VP1 and offers promising prospects for improved diagnostic capability.

摘要 : Carbon based electrode materials have many advantages such as large specific surface area, good electrical conductivity, easy obtained, safety and non-toxicity. In this work, we have induced the synthesis of MnO 2 -g-C 3 N 4 /C composites using the apricot mushroom as a biological template. The rod-shaped MnO 2 is uniformly anchored on the surface of g-C 3 N 4 /C. Structural design of MnO 2 -g-C 3 N 4 /C composites improves the poor electrical conductivity of single MnO 2 . The results show that biocarbon has good stability and conductivity, g-C 3 N 4 provides more reactive sites, and MnO 2 substantially enhances the pseudocapacitance of the material, thus realize the synergistic effect for higher supercapacitor property. Based on its excellent three-phase interface structure, the MnO 2 -g-C 3 N 4 /C' capacitance was able to reach 276F·g −1 with a capacitance retention of 96 % after 1000 cycles. Therefore, this material has potential application in the energy storage industry.

摘要 : CQDs (Carbon quantum dots) were obtained by hydrothermal method with lemon juice as the carbon source. CuS/CQDs/g-C3N4 was synthesized using copper trihydrate nitrate (Cu(NO3)2·3H2O), thiourea(CH4N2S) and lemon juice as starting materials via ultrasonic shock method. CuS/CQDs/g-C3N4 three-phase composite photocatalyst with p-n-type heterojunction structure was obtained successfully. The structure and morphology of the material were analyzed by various methods, such as XRD, SEM, TEM, XPS, PL, BET and UV-Vis. The results showed that the interface structure is well constructed with high purity and uniform distribution. In the photocatalytic degradation experiment, the best photocatalytic degradation of the CuS/CQDs/g-C3N4 composite was achieved at approximately 72.1% when the CuS content was 10wt%. After the RhB degradation in 4 cycles, the photocatalytic degradation efficiency of the composite material was not significantly reduced, and it still remained at 65.2%. Finally, it is clear that ·O2-radical is the main factor in photocatalytic degradation, and h+ radical is the second factor.

摘要 : Ni-rich layered materials Li[NixCoyMnzAl1–x–y–z]O2 (x > 0.8) are regarded as the competitive cathode for practical applications in lithium-ion batteries owing to the large discharging capacity. Nevertheless, the strong oxidation activity, the poor structure, and the thermal stability at the electrode-electrolyte interface would lead to much trouble, for example, inferior electrochemical properties and acute safety issues. To ameliorate the above problems, this work reports a strategy for the double modification of F– doping and LiNbO3 covering in LiNi0.88Co0.06Mn0.03Al0.03O2 cathode via using high-temperature calcining and ball-milling technology. As a result, the cathodes after F– doping and LiNbO3 covering not only demonstrate a more stabilized crystal structure and particle interface but also reduce the release of high-activity oxygen species to ameliorate the thermal runaway. The electrochemical tests show that the LiNbO3–F–-modified cathode displays a superior rate capability of 159.3 mAh g–1 at 10.0 C and has the predominant capability retention of 92.1% in the 200th cycle at 25 °C, much superior than those (125.4 mAh g–1 and 84.0%) of bare cathode. Thus, the F- doped and LiNbO3-coated Ni-rich oxides could be a promising cathode to realize the high capacity and a stabilized interface.

摘要 : With the rapid depletion of fossil fuels and a series of environmental problems, it is urgent to develop and to utilize new electrochemical energy storage devices, and the design, preparation and optimization of electrode materials are key factors to determine the performance of supercapacitors. Hydrothermal method was used to convert hollyhock stalks into porous carbon matrix with MnO and Co nanocrystals anchored on it. Results show that the prepared biocarbon has porous structure and good electron transport properties, and the nanosrystal MnO-Co on it has high capacitance. Due to the unique nanostructure of carbon skeleton and large specific surface area (345.9 m2·g-1), MnO-Co nanocrystal/porous carbon shows excellent electrochemical capacitance (146 F·g-1 at 1 A·g-1) and cycle stability. After 1000 cycles, the specific capacity still remains 99.4%.

摘要 : Groundwater environments are complex, and traditional advanced oxidation technologies mainly based on free radicals have limitations such as poor selectivity and low interference resistance, making it difficult to efficiently degrade target pollutants in groundwater. Therefore, we developed a sludge-based biochar-supported FeMg-layered double hydroxide catalyst (BC@FeMg-LDH) for the catalytic degradation of 2, 4-dichlorophenol (2, 4-DCP) using persulfate (PDS) as an oxidant. The removal efficiency of the catalyst exceeded 95%, showing high oxidation activity in a wide pH range while being almost unaffected by reducing substances and ions in the environment. Meanwhile, under neutral conditions, the leaching of metal ions from BC@FeMg-LDH was minimal, thereby eliminating the risk of secondary pollution. According to quenching experiments and electron paramagnetic resonance spectroscopy, the main active species during BC@FeMg-LDH/PDS degradation of 2, 4-DCP is 1O2, indicating a non-radical reaction mechanism dominated by 1O2. Characterization techniques, including X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, revealed that the carbonyl (C = O) and metal hydroxyl (M-OH) groups on the material surface were the main reactive sites mediating 1O2 generation. The 1O2 generation mechanism during the reaction involved ketone-like activation of carbonyl groups on the biochar surface and complexation of hydroxyl groups on the material surface with PDS, resulting in the formation of O2·− and further generation of 1O2. 1O2 exhibited high selectivity toward electron-rich organic compounds such as 2, 4-DCP and demonstrated strong interference resistance in complex groundwater environments. Therefore, BC@FeMg-LDH holds promising applications for the remediation of organic-contaminated groundwater.

摘要 : In the work, we have focused on the surface variations of the LiNi0.90Co0.04Mn0.03Al0.03O2 induced by the lithium ion conductor Li0.34La0.56TiO3 and over-lithiated oxide Li2NiO2 double coverings. The influence of various covering materials on particles morphology, crystal structure and electrochemical properties have been explored. It is found that the Li0.34La0.56TiO3 firm layer could reduce the catalytic decomposition of electrolyte and further maintain the stable particles morphology and crystal structure of cathode after long-term cycling. In addition, the Li2NiO2 served as the lithium supplement additive could compensate the irreversible active lithium ions loss during cycling and then relieve the cyclic capacity attenuation. Comparatively, the cathodes after Li0.34La0.56TiO3 coating deliver the obvious enhanced rate capability, superior discharging capacity at low temperature and more stable cyclic performance than those of pristine LiNi0.90Co0.04Mn0.03Al0.03O2. Besides, the Li0.34La0.56TiO3 and Li2NiO2 co-coated sample demonstrates the superior safety performance and cyclic stability when applied in the pouch battery in comparison with the pristine cathode. © 2023