Methane activation by closed-shell tantalum sulfide anions TaS_(3)^(-)

Methane is a vital feedstock while the intrinsic inertness of CH_(4)molecule hinders the conversion of methane under mild conditions.Investigating and understanding the mechanism of methane activation is of great importance in chemistry.In this study,tantalum sulfide anions TaS_(3)^(-)were generated by laser ablation method and mass-selected by a quadrupole mass filter to react with methane,ethane,and propane in an ion funnel trap reactor under thermal collision conditions.The reactant and product ions were detected by a time-of-flight mass spectrometer.Experimental results demonstrate that TaS_(3)^(-)is able to adsorb all of the alkane molecules and break the robust C-H bonds.Further density functional theory calculations reveal that TaS_(3)^(-)is a closed-shell species and effectively activates methane via the Ta^(δ+)-S^(δ-)Lewis acid-base pair(LABP,CH_(4)+Ta^(δ+)-S^(δ-)→CH_(3)-Ta-S-H).With a comparative study with NbS_(3)^(-)that contains the Nbδ+-S^(δ-)LABP,the higher reactivity of TaS_(3)^(-)than that of NbS_(3)^(-)can be attributed to the more acidity of Ta^(δ+)than that of Nbδ+.To the best of our knowledge,this study reports the first example of gas phase species TaS_(3)^(-)to activate methane through the metal-sulfur LABP under thermal collision conditions.

Vertically aligned NiS nano-flakes derived from hydrothermally prepared Ni(OH)2 for high performance supercapacitor

In present work,the vertically aligned Ni S nano-flakes composed thin film is prepared by anionic exchange process in which hydrothermally prepared Ni（OH）2is used as a parent thin film and Na2S as a sulfide ion source.This synthesis process produced fully transformed and shape-controlled nano-flakes of Ni S from nano-flowers of Ni（OH）2.The electrochemical supercapacitor properties of Ni S electrode are studied with cyclic voltammetry（CV）,galvonostatic charge discharge（GCD）and electrochemical impedance spectroscopy（EIS）techniques.Highly porous surface area（85 m^2/g）of Ni S nano-flakes makes large material contribution in electrochemical reaction stretching specific capacitance（Cs）of 880 F/g at scan rate of 5 m V/s and 90%electrochemical stability up to 4000 CV cycles in 2 M KOH electrolyte.Further,the flexible solid-state symmetric supercapacitor device（Ni S/PVA–Li ClO4/Ni S）has been fabricated using Ni S electrodes with polyvinyl alcohol（PVA）–lithium perchlorate（Li ClO4）gel electrolyte.The Ni S/PVA–Li ClO4/Ni S device exhibits specific capacitance of 56 F/g with specific energy of 14.98 Wh/kg and excellent cycling stability after 2000 cycles.In addition,the Ni S/PVA–Li ClO4/Ni S device demonstrates illumination of red light emitting diode（LED）for 60 s,which confirms the practical applicability of Ni S/PVA–Li ClO4/Ni S device in energy storage.