Latest ArticlesPhosphorus-doped mesoporous carbons (PMCs) were prepared using a self-doping and self-templating approach via direct pyrolysis of sodium phytate (C6H17NaO24P6). The one-pot method allows simultaneous carbonization and P doping, eliminating the need for pre-synthesis or post-activation treatment. The C6H17NaO24P6 is the source of both carbon and phosphorus, and the nano-Na4P2O7 particles produced during pyrolysis act as hard templates for the honeycomb mesoporous structure with high specific surface area (884–827 m2/g), large mesopore volume ratio (67%–75%) and rich phosphorus content (0.53–2.34 at%). As electrodes of supercapacitors in 6 mol/L KOH, the PMCs showed outstanding performance with a high capacitance of 202 F/g and excellent rate performance of 148 F/g at 30 A/g. In addition, the PMCs-based symmetrical supercapacitors can operate in an expanded working voltage of 0–1.6 V in 3 mol/L H2SO4 aqueous electrolytes with high-density energy of 11.8 Wh/kg.
1,4-Enyne units are ubiquitous skeletons in biologically active molecules and natural products. Especially, they represent versatile building blocks for abundant downstream derivatizations via controllable modifications of both alkene and alkyne units independently. Recently, great efforts have been made to establish efficient protocols to achieve optically active 1,4-enynes. Considering the enormous application potential of enantioenriched 1,4-enyne units but no related review on this topic has been described, here we aim to provide a comprehensive summary on the catalytic methods established for enantioselective constructions of these intriguing skeletons. According to the reaction types, this review is divided into five parts, including asymmetric allylic substitution, asymmetric propargylic substitution, asymmetric alkynylallylic substitution, asymmetric hydroalkynylation and asymmetric 1,2-addition of alkynes to conjugated imines or ketones.
Electrochemical oxidation of aqueous tris(1,3-dichloro-2-propyl) phosphate (TDCPP) by using Ti/SnO2-Sb/La-PbO2 as anode was investigated for the first time, and the degradation mechanisms and toxicity changes of the degradation intermediates were further determined. Results suggested that electrochemical degradation of TDCPP followed pseudo-first-order kinetics, and the reaction rate constant (k) was 0.0332 min−1 at the applied current density of 10 mA/cm2 and Na2SO4 concentration of 10 mmol/L. There was better TDCPP degradation performance at higher current density. Free hydroxy radical (·OH) was proved to play dominant role in TDCPP oxidation via quenching experiment, with a relative contribution rate of 60.1%. A total of five intermediates (M1, C6H11Cl4O4P; M2, C3H7Cl2O4P; M3, C9H16Cl5O5P; M4, C9H14Cl5O6P; M5, C6H10Cl3O6P) were identified, and the intermediates were further degraded prolonging with the reaction time. Flow cytometer results suggested that the toxicity of TDCPP and degradation intermediates significantly reduced, and the detoxification efficiency was achieved at 78.1% at 180 min. ECOSAR predictive model was used to assess the relative toxicity of TDCPP and the degradation intermediates. The EC50 to green algae was 3.59 mg/L for TDCPP, and the values raised to 84, 574, 54.6, 391, and 8920 mg/L for M1, M2, M3, M4, and M5, respectively, indicating that the degradation intermediates are less toxic or not toxic. Electrochemical advanced oxidation process is a valid technology to degrade TDCPP and pose a good detoxification effect.
The organic carbon source coating LiFexMn1-xPO4 suffers from the problem of non-uniform carbon cladding. Too thick carbon cladding layer instead hinders the de-embedding of lithium ions. In this paper, we choose cornstalk as the carbon source, then LiFe0.5Mn0.5PO4@cornstalk-C (LFMP@C-C) with 3D anchoring structure is prepared by the solvothermal method. The results show that the LFMP with cornstalk as the carbon source has better performance compared to the sucrose-coated LFMP material (LFMP@C). The discharge capacity of LFMP@C-C is 116 mAh/g for the first cycle at 1 C and the capacity retention rate is 94.0% after 500 cycles, and the discharge capacity of LFMP@C-C is more than 17.17% higher than that of LFMP@C.
Anthropogenic carbon dioxide (CO2) emission from the combustion of fossil fuels aggravates the global greenhouse effect. The implementation of CO2 capture and transformation technologies have recently received great attention for providing a pathway in dealing with global climate change. Among these technologies, electrochemical CO2 capture technology has attracted wide attention because of its environmental friendliness and flexible operating processes. Bipolar membranes (BPMs) are considered as one of the key components in electrochemical devices, especially for electrochemical CO2 reduction and electrodialysis devices. BPMs create an alkaline environment for CO2 capture and a stable pH environment for electrocatalysis on a single electrode. The key to CO2 capture in these devices is to understand the water dissociation mechanism occurring in BPMs, which could be used for optimizing the operating conditions for CO2 capture and transformation. In this paper, the references and technologies of electrochemical CO2 capture based on BPMs are reviewed in detail, thus the challenges and opportunities are also discussed for the development of more efficient, sustainable and practical CO2 capture and transformation based on BPMs.
Despite the 1,2-difunctionalization reactions of styrenes have been well developed, the 1,1-regioselective addition reaction remains challenging. We disclose herein a palladium-catalyzed, highly 1,1-regioselective alkenylboration of styrenes by using alkenyl triflates and a diboron reagent as the coupling partners. A wide scope of styrenes derivatives and alkenyl triflates participate this reaction to provide the corresponding allyl boronates with high regioisomeric ratios. The success of this reaction is ascribed to the application of 1,10-phenanthroline-derivated ligand and the addition of ammonium chloride salt. Moreover, acrylate esters can also selectively afford the 1,1-alkenylboration products under the same reaction conditions.
Spatial configuration has a significant effect on chemical self-assembly. However, the importance of spatial configuration in supramolecular adhesive materials has been frequently ignored. In this study, the effects of the spatial configuration on cohesion and adhesion were investigated. Owing to the diversities of the chemical structures and assembly patterns, 1,2-disubstituted cyclohexane derivatives were used in this combined experimental and theoretical investigation. The self-sorting assembly of enantiopure isomers improved cohesion but had a negative effect on adhesion. In contrast, racemic mixtures displayed stronger adhesion effects. Moreover, it was proven that the cis-configuration was more favorable for supramolecular adhesion than the trans-counterpart. In addition, the influence of the spatial configuration of 1,2-disubstituted cyclohexane derivatives could be effectively mitigated by hydrogen bond donors or acceptors. The addition of natural acids yielded three-dimensional polymeric networks, in which the spatial configuration was not the decisive factor for supramolecular adhesion.
Electrochemical reduction of CO2 (CO2RR) to value-added chemicals is an attractive strategy for greenhouse gas mitigation and carbon recycle. Carbon material is one of most promising electrocatalysts but its product selectivity is limited by few modulating approaches for active sites. Herein, the predominant pyridinic N-B sites (accounting for 80% to all N species) are fabricated in hierarchically porous structure of graphene nanoribbons/amorphous carbon. The graphene nanoribbons and porous structure can accelerate electron and ion/gas transport during CO2RR, respectively. This carbon electrocatalyst exhibits excellent selectivity toward CO2 reduction to CH4 with the faradaic efficiency of 68% at -0.50 V vs. RHE. As demonstrated by density functional theory, a proper adsorbed energy of *CO and *CH2O are generated on the pyridinic N-B site resulting into high CH4 selectivity. Therefore, this study provides a novel method to modulate active sites of carbon-based electrocatalyst to obtain high CH4 selectivity.
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