Preparation And Electrochemical Study Of Transition Metal Sulfide/Porous Carbon Nanocomposites

Since the 20th century,energy exhaustion and environmental problems have become increasingly serious,the development and utilization of new energy has become a hot issue of the up-to-date society.Currently,the development of efficient clean energy and storage strategies are urgent.Hydrogen Energy is one of the most promising clean energy,and electrocatalytic water decomposition is an important method for hydrogen production.Supercapacitors as a new energy storage device have the advantages of fast charging∕discharging,high power density,and long service life.To improve the efficiency of electrocatalytic water splitting and the electrochemical performance of supercapacitors,a series of transition metal sulfides（TMS）were prepared on hierarchical porous carbon microrods（HPCM）that are composed by graphene-like nanosheets,and the electrochemical properties of various electrode materials for applications of supercapacitors and electrocatalytic water splitting were studied.The main contents are as follows:（1）Ni₃S₄-HPCM nanocomposite was synthesized by one-step hydrothermal method using thioacetamide as the sulfur source.Scanning electron microscope（SEM）,transmission electron microscope（TEM）,and X-ray diffraction（XRD）characterizations indicated that Ni₃S₄nanoparticles were uniformly grown on the HPCM.Ni₃S₄-HPCM as the electrode material for supercapacitor has a high specific capacitance(1950 F g^-11 at a current density of 1 A g^-1),and retains an initial value of92.5%after 500 cycles.At the same time,the electrocatalytic hydrogen evolution（HER）performance test show that in 1 M KOH solution,Tafel obliquely is 93.9 mV dec^-1,current density is 10 mA cm^-2,the overpotential is 282 mV.（2）Co₃S₄-HPCM nanocomposites were prepared by one-step hydrothermal method.SEM,TEM and XRD characterizations indicated that Co₃S₄ nanoparticles were uniformly grown on the HPCM.Co₃S₄-HPCM as the electrode material for supercapacitors has a high specific capacitance(768.2 F g^-11 at a current density of 1 A g^-1),and retains the initial value of 89.5%after 500 cycles.In addition,the HER performance tests show that the overpotential of Co₃S₄-HPCM in 1 M KOH solution was 98.5 mV at a current density of 10 mA cm^-2,with a Tafel slope of 50.6 mV dec^-1.（3）The NiCo₂S₄-HPCM nanocomposite was synthesized by a green and simple hydrothermal method.SEM,TEM and XRD characterizations indicated that Ni Co₂S₄ nanoparticles were uniformly grown on the HPCM.NiCo₂S₄-HPCM as the electrode material for supercapacitors has a high specific capacitance(1253 F g^-11 at a current density of 1 A g^-1),and retains an initial value of 87.1%after 500 cycles.The HER performance tests show that in a 1 M KOH solution the overpotential is 152 mV at a current density of 10 mA cm^-2,with a Tafel slope of 75.5 mV dec^-1,and.The electrocatalytic oxygen evolution reaction（OER）performance tests show that the overpotential is 381 mV at a current density of 10 mA cm^-2,with a Tafel slope of 31.6 mV dec^-1.