Reduced graphene oxide doping flower-like Fe_(7)S_(8) nanosheets for high performance potassium ion storage

Finding easy-to-operate strategy to obtain anode material with well-designed structure and excellent electrochemical performance is necessary to promote the development of the future potassium-ion batteries(PIBs).In this work,we synthesized reduced graphene oxide doping flower-like Fe_(7)S_(8) nanosheets electrode materials using one-step hydrothermal strategy.The rGO@Fe_(7)S_(8) composite is composed of homogeneous Fe_(7)S_(8) and reduced graphene oxide thin nanosheets.This unique structure not only promotes the penetration of electrolyte and increases the conductive of the pure Fe_(7)S_(8) electrode materials,but also relieves the volume expansion of K^(+) during charge/discharge process.When applied this interesting anode electrode for PIBs,the rGO@Fe_(7)S_(8) exhibits excellent electrochemical performance.It delivers a high reversible specific capacity of 445 mAh g^(-1) at 50 mA g^(-1),excellent rate performance(284 mAhg^(-1)at 500 mA g^(-1) and 237 mAh g^(-1) at 1000 mA g^(-1)),and a high cycling stability at 100 mA g^(-1)(maintained 355 mAh g^(-1) after 300 cycles).

Influence of doping nitrogen on the catalytic performance of carbon nanotubes encapsulating cobalt for selective oxidation of arylalkanes

Efficient selective oxidation of hydrocarbons to corresponding ketones has been a significant but challenging work in the past decades.Here,a nitrogen-doped bamboo-like carbon nanotubes encapsulating cobalt catalyst(NCNTs-X)using citric acid,melamine and CoCl_(2)·6H_(2)O as precursors was synthesized by a simple pyrolysis method.A series of characterization techniques were employed to investigate the physicochemical properties of samples.And the results show that the as-prepared catalysts achieve a high catalytic performance for selective ethylbenzene oxidation(78.3% ethylbenzene conversion)using molecular oxygen as oxidant,especially giving a high selectivity(93.8% selectivity to acetophenone).According to the investigation of the structure-activity relationship of the catalysts,it can be deduced that the Co-N_(x) sites have an obvious positive effect on catalytic performance thanks to the synergistic effect between metallic cobalt and pyridinic N.