Latest ArticlesThe development of the preparation strategy for high-quality and large-size graphene via eco-friendly routes is still a challenging issue. Herein, we have successfully developed a novel route to chemically exfoliate natural graphite into high-quality and large-size graphene in a binary-peroxidant system. This system is composed of urea peroxide (CO(NH2)2·H2O2) and hydrogen peroxide (H2O2), where CO(NH2)2·H2O2 is used in preparing graphene for the first time. Benefiting from the complete decomposition of CO(NH2)2·H2O2 and H2O2 into gaseous species under microwave (MW) irradiation, no water-washing and effluent-treatment are needed in this chemical exfoliation procedure, thus the preparation of graphene in an eco-friendly way is realized. The resultant graphene behaves a large-size, high-quality and few-layer feature with a yield of ~100%. Then 4 µm-thick ultrathin graphene paper fabricated from the as-exfoliated graphene is used as an electromagnetic interference (EMI) shielding material. And its absolute effectiveness of EMI shielding (SSE/t) is up to 34, 176.9 dB cm2/g, which is, to the best of our knowledge, among the highest values so far reported for typical EMI shielding materials. The EMI shielding performance demonstrates a great application potential of graphene paper in meeting the ever-increasingly EMI shielding demands in miniaturized electronic devices.
Hydrogen fuel cells are among the promising energy sources worldwide, which could accomplish cyclic production of energy and avoid the emission of green-house or contaminative byproducts. However, sulfur compounds (SCs) even at trace level (nmol/mol) are usually involved in cell construction and further H2 production, which would cause degradation of the catalysts and shorten the lifetime of the fuel cells. Moreover, the highly reactive SCs could cause varied species and concentrations of them in complex matrices, so online rather than offline analysis of SCs in H2 would be preferred. In this context, we developed a new system combining online cryogenic preconcentration of nine SCs and subsequent determination by GC-SCD (sulfur chemiluminescent detector), with the correlation coefficients of the calibration curves higher than 0.999, calculated limits of detection no higher than 0.050 nmol/mol, analytical time around 30 min per sample, and satisfactory precision and accuracy (RSD < 5% and SD < 15%). The analytical performance was much better than or at least comparable to the previously reported and the developed system was successfully applied for real sample analysis.
In this work, two aza-BODIPY derivatives, 3,5-diphenyl-1,7-di(p-dodecyloxyphenyl)-aza-BODIPY (CJF) and 3,5-di(p-bromophenyl-1,7-di(p-dodecyloxyphenyl)-aza-BODIPY (2Br-CJF) acted as model molecules to form the self-assembly monolayers on the solid-liquid interface. With the utilizing of scanning tunnelling microscope (STM), we demonstrated that intermolecular Br…F—BF interactions existed in 2Br-CJF self-assembly structure and played an important role in strengthening the stability of 2Br-CJF self-assembly structure. This result is supported by density functional theory (DFT) calculation.
The trade-off between the electrochemical performance and mechanical strength is still a challenge for Ti3C2Tx free-standing electrode. Herein, a facile approach was proposed to fabricate a Microfibrillated cellulose@Ti3C2Tx (MFC@Ti3C2Tx) self-assembled microgel film by means of hydrogen bonding linkage. Benefiting from the rich hydroxyl groups on the MFC, the Ti3C2Tx nanosheets coated on the MFC in a time scale of minutes (within 1 min) instead of hours. The ultralong 1D frame of MFC effectively mitigated the re-aggregation of Ti3C2Tx nanosheet. The fluffy MFC@Ti3C2Tx film structure and the constructed 1D/2D conducting Ti3C2Tx pathways in horizontal and vertical directions endowed the fast ion transport of the electrolytes and the improved accessibility to the Ti3C2Tx surface. As a result, the freestanding MFC@Ti3C2Tx microgel film delivered a high specific capacitance of 451 F/g. And the rate performance was increased to 71% from the 64% of that of pristine Ti3C2Tx film. Furthermore, the tensile strength of MFC@Ti3C2Tx film was also promoted to 46.3 MPa, 3 folds of that of the pristine Ti3C2Tx film, due to the high strength of MFC and the hydrogen bonding effect.
A condition-controlled strategy for selectively synthesis of 2-acylbenzothiazoles and bibenzo[b][1, 4]thiazines from aryl methyl ketones and disulfanediyldianilines was realized using I2/DMSO or I2/MeCN systems, respectively. The desired products were synthesized in only 15 min with moderate to excellent yields (50%-90%) under microwave-assisted, metal-free conditions. The strategy provides a great advantage for selective synthetic applications in the efficient synthesis of benzothiazoles and bibenzothiazines heterocycle compounds.
Recently, widespread attention has been devoted to the typical layered BiOCl or BiOBr because of the suitable nanostructure and band structure. However, owing to the fast carrier recombination, the photocatalytic performance of BiOX materials is not so satisfactory. Loading 1T phase WS2 nanosheets (NSs) onto Bi5O7Br NSs can improve the photocatalytic N2 fixation activity. Among these, the obtained 1T-WS2@Bi5O7Br composites with optimum 5% 1T-WS2 NSs display a significantly improved photocatalytic N2 fixation rate (8.43 mmol L-1h-1g-1), 2.51 times higher than pure Bi5O7Br (3.36 mmol L-1h-1g-1). And the outstanding stability of 1T-WS2@Bi5O7Br-5 composites is also achieved. Exactly, the photoexcited electrons from Bi5O7Br NSs are quickly transferred to conductive 1T phase WS2 as electron acceptors, which can promote the separation of carriers. In addition, 1T-WS2 NSs can provide abundant active sites on the basal and edge planes, which can promote the efficiency of photocatalytic N2 fixation. This work offers a novel solution to improve the photocatalytic performance of Bi5O7Br NSs.
Modifying electrochemical surface area (ECSA) and surface chemistry are promising approaches to enhance the capacities of oxygen cathodes for lithium-oxygen (Li-O2) batteries. Although various chemical approaches have been successfully used to tune the cathode surface, versatile physical techniques including plasma etching etc. could be more effortless and effective than arduous chemical treatments. Herein, for the first time, we propose a facile oxygen plasma treatment to simultaneously etch and modify the surface of Co3O4 nanosheet arrays (NAs) cathode for Li-O2 batteries. The oxygen plasma not only etches Co3O4 nanosheets to enhance the ECSA but also lowers the oxygen vacancy concentration to enable a Co3+-rich surface. In addition, the NA architecture enables the full exposure of oxygen vacancies and surface Co3+ that function as the catalytically active sites. Thus, the synergistic effects of enhanced ECSA, modest oxygen vacancy and high surface Co3+ achieve a significantly enhanced reversible capacity of 3.45 mAh/cm2 for Co3O4 NAs. This work not only develops a promising high-capacity cathode for Li-O2 batteries, but also provides a facile physical method to simultaneously tune the nanostructure and surface chemistry of energy storage materials.
Na3V2(PO4)3 is a very prospective sodium-ion batteries (SIBs) electrode material owing to its NASICON structure and high reversible capacity. Conversely, on account of its intrinsic poor electronic conductivity, Na3V2(PO4)3 electrode materials confront with some significant limitations like poor cycle and rate performance which inhibit their practical applications in the energy fields. Herein, a simple two-step method has been implemented for the successful preparation of carbon-coated Na3V2(PO4)3 materials. As synthesized sample shows a remarkable electrochemical performance of 124.1 mAh/g at 0.1 C (1 C = 117.6 mA/g), retaining 78.5 mAh/g under a high rate of 200 C and a long cycle-performance (retaining 80.7 mAh/g even after 10000 cycles at 20 C), outperforming the most advanced cathode materials as reported in literatures.
The efficient utilization of solar energy through photocatalysis is ideal for solving environmental issues and the development sustainable future. BiOBr-based semiconductors possess unique narrowed bandgaps and layered structures, thereby widely studied as photocatalysts for environmental remediation. However, a little has been focused on the comprehensive reviewing of BiOBr despite its extensive and promising applications. In this review, the state-of-the-art developments of BiOBr-based photocatalysts for environmental remediation are summarized. Particular focus is paid to the synthetic strategies for the control of the resulting morphologies, as well as efficient modification strategies for improving the photocatalytic activities. These include boosting the bulk phase by charge separation, enhancing the spatial charge separation, and engineering the surface states. The environmental uses of BiOBr-based photocatalysts are also reviewed in terms of purification of pollutants and CO2 reduction. Finally, future challenges and opportunities of BiOBr-based materials in photocatalysis are discussed. Overall, this review provides a good basis for future exploration of high-efficiency solar-driven photocatalysts for environmental sustainability.
Crystalline engineering and heterostructure have attracted much attention as effective strategies to improve the electrocatalytic activity for hydrogen evolution reaction (HER). In this study, a new heterostructure catalyst (Ru/RuS2@N-rGO) with low crystallinity was fabricated by a simple and low-temperature method for HER in alkaline solution, applying the Na2SO4 as S source and polypyrrole as N source. Optimizing through the controllable crystalline engineering and composition ratio of Ru and RuS2, the Ru/RuS2@N-rGO heterocatalyst at the calcining 500 ℃ revealed highly efficient HER activity with overpotential 18 mV at a current density 10 mA/cm2 and remarkable stability for 24 h in 1.0 mol/L KOH. This work provides a facile and effective method in designing advanced electrocatalysts for HER in the alkaline electrolytes by synergistically structural and component modulations.
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