Supercapacitive properties of MnNiS_(x)@Ti_(3)C_(2)T_(x) MXene positive electrode assisted by functionalized ionic liquid

MnNiS_(x)@Ti_(3)C_(2)T_(x)as the positive electrode of supercapacitor was successfully prepared by hydrothermal method with the assistance of amino-functionalized ionic liquids.The micromorphological structures of MnNiS_(x)@Ti_(3)C_(2)T_(x)were analyzed using X-ray diffraction,scanning electron microscope,X-ray photoelectron spectroscopy,transmission electron microscope,and energy dispersive spectrometer to reveal the synergistic effect between MnNiSxand Ti_(3)C_(2)T_(x)MXene.MnNiS——x grew into a three-dimensional coral-like structure on the surface and between layers of Ti_(3)C_(2)T_(x)nanosheets.This structure alleviated the collapse and stacking of Ti_(3)C_(2)T_(x),increased the specific surface area of Ti_(3)C_(2)T_(x),and promoted the charges transfer on the surface of Ti_(3)C_(2)T_(x).The electrochemical performances of MnNiS_(x)@Ti_(3)C_(2)T_(x)positive electrode,such as cyclic voltammetry,galvanostatic charge/discharge,and electrochemical impedance spectroscopy,were investigated.The synergistic effect between MnNiSxand Ti_(3)C_(2)T_(x)MXene improved the specific capacitance and the capacitance retention of the MnNiS_(x)@Ti_(3)C_(2)T_(x)electrode.An asymmetric solid-state supercapacitor(ASC)assembled using MnNiS_(x)@Ti_(3)C_(2)T_(x)as cathode material had the power density of 816.34 W·kg^(-1),and the energy density of 35.11 Wh·kg^(-1).The capacitance retention of ASC reached 98% after 5000 cycles at a current density of 5 A·g^(-1).

Enhanced electrochemical performance of CoNiS_(x)@Ti_(3)C_(2)T_(x)electrode material through in-situ doping of cobalt element

The composite electrode of CoNiS_(x)and Ti_(3)C_(2)T_(x)MXene was successfully prepared using a onestep hydrothermal method under the in-situ doping of the cobalt element.The effects of in-situ doping of the cobalt element on the micromorphology and electrochemical performance of the electrodes were investigated.After insitu doping of the cobalt element,NiS with a needle-like structure was converted into a CoNiS_(x)with petal-like structure.The petal-like CoNiS_(x)with a rough surface was very dense and evenly wrapped on the surface and interlamination of Ti_(3)C_(2)T_(x),which helped increase the specific surface area and pore volume of the electrode.Under the identical test conditions,CoNiS_(x)@Ti_(3)C_(2)T_(x)had a higher specific capacitance and capacitance retention than NiS@Ti_(3)C_(2)T_(x).This result indicated that the in-situ doping of the cobalt element promoted the electrochemical performance of the electrode.The energy density of the CoNiS_(x)@Ti_(3)C_(2)T_(x)/nickel foam(NF)//activated carbon(AC)/NF asymmetric supercapacitor device was 59.20 Wh·kg^(–1)at a power density of 826.73 W·kg^(–1),which was much higher than that of NiS@Ti_(3)C_(2)T_(x)/NF//AC/NF.Three CoNiS_(x)@Ti_(3)C_(2)T_(x)/NF//AC/NF in series were able to illuminate the light emitting diode lamp for about 10 min,which was higher than the 5 min of three NiS@Ti_(3)C_(2)T_(x)/NF//AC/NF in series under the same condition.The CoNiS_(x)@Ti_(3)C_(2)T_(x)/NF//AC/NF with high energy density had better application potential in energy storage than the NiS@Ti_(3)C_(2)T_(x)/NF//AC/NF.

Spectroscopic analysis of acetamide-AlCl_(3)-based ionic liquid analog and their catalytic performance in isobutene oligomerization

The spectral structures of acetamide-AlCl_(3)-based ionic liquid(IL)analogs were determined in detail through IR,NMR,and Raman spectroscopy.IR spectroscopy showed that 0.65AA-1.0AlCl_(3) was the coordination structure of Al and O atoms because of the resonance structure of acetamide.The mutual verification of the results of ^(27)Al NMR and ^(1)H NMR indicated that acetamide coexisted mainly in the form of cationic Al species and molecular Al species in xAA-1.0AlCl_(3),and AA/AlCl_(3) molar ratio affected the transformation of cationic Al species to molecular Al species.xAA-1.0AlCl_(3) was used as a green acidic catalyst for isobutene oligomerization,and the effects of AA/AlCl_(3) molar ratio,reaction temperature,reaction time,and volumetric ratio between IL analog and isobutene on product distribution were investigated.Optimal reaction conditions were AA/AlCl_(3) molar ratio of 0.75,reaction temperature of 60 C,reaction time of 30 min,and catalyst/i-C4¼volumetric ratio of 1.4 v/v.Under optimal conditions,isobutene conversion,(C8^(-)+C12^(-))selectivity,(C16^(-)+C20^(-))selectivity,and by-product selectivity were 85.26,80.20,6.80,and 13.00 wt%,respectively。