One-step Hydrothermal Synthesis,Characterizations,Sensing And Energy Application Of Graphene And Graphene-like/inorganic Nanoparticles Hybrid

This work revolves around three parts.In the first part,a facile one-step hydrothermal synthesis strategy is utilized for the preparation of three-dimensional(3D)coral-like structural MoS2/Cu2O porous nanohybrid which is applied as bifunctional material for biosensor and oxygen reduction reaction(ORR)applications.Due to the combination of p-type Cu2O nanoparticles and n-type MoS2 nanosheets,MoS2/Cu2O nanohybrid exhibits great potential in both biosensor and electrochemical catalyst.In addition,the special 3D coral-like porous structure endows MoS2/Cu2O nanohybrid a large specific surface area which enhances its electrocatalyst performance significantly.The morphology and composition of MoS2/Cu2O nanohybrid were characterized by scanning electron microscope,transmission electron microscope,X-ray diffraction,specific surface&pore analysis instrument and X-ray photoelectron spectroscopy.The uniform Cu20 nanoparticles with an average diameter of 5-10 nm were successfully decorate on the surface of MoS2 layers.The electrochemistry measurement results indicate that the hydrogen peroxide(H2O2)biosensor fabricated by MoS2/Cu2O nanohybrid shows a wide linear range,low limitation of detection,high selectivity,and long-term stability.At the same time,the coral-like structural MoS2/Cu2O nanohybrid also displays excellent ORR electrochemical catalysis performance.It can be anticipated that the strategies utilized in this work will not only guide the functional design of novel nanohybrid materials but also extend their potential applications in energy storage,waste water purification,and environmental engineering.The second part mainly focuses on a facile one-step hydrothermal synthesis to prepare molybdenum disulfide nanosheets decorated with gold nanoparticles(MoS2/AuNP)for rechargeable Li-O2 batteries.The fabricated Li-O2 battery exhibits enhanced specific capacity and cycle efficiency,which are ascribed to the two-dimensional structure of MoS2/AuNP nanohybrids and the synergistic catalytic effects of both MoS2 nanosheets and AuNPs.The SEM,Raman spectra and XRD analysis measurements were used to identify the discharge products of Li-O2 batteries with MoS2/AuNP nanohybrids.The results indicate that Li2O2,as the major discharge product,is reversibly formed in a discharging process.Compared to previous reports,our strategy for producing MoS2/AuNP nanohybrids has several advantages,such as highly-efficient,economic,and simple.With the large specific surface area and highly exposed edges of MoS2 nanosheets,AuNPs were attached onto them with ultrafine size,Governing by the excellent electrocatalytic activities of MoS2 and AuNPs,the MoS2/AuNP nanohybrids as catalyst exhibited superior Li-O2 battery performance with low discharge overpotential,high specific capacity,and good cyclability.Therefore,we expect this one-step economic hydrothermal synthesis method can be utilized to prepare other functional materials based on layered TMD materials and metal nanoparticles,and further applied in catalysis,surface-enhanced Raman scattering,energy storage,and biosensors.The final part mainly introduces ultradispersed SnO2 nanodots anchored on graphene for a quasi-solid-state sodium ion capacitor with high energy density and robust cycle life.The appearance of sodium ion capacitors(NICs)is regarded as the beginning of an era of increased energy density and reduced cost in the field of electrochemical capacitor.However,it is a great challenge to find a suitable negative electrode material with low cost and superior electrochemical performance.Herein,ultradispersed SnO2 nanodots anchored on graphene(G/SnO2ND)was fabricated by a facile one-step reaction with a hydrothermal method,and further utilized as a fascinating negative electrode material for a quasi-solid-state NIC.The as-prepared G/SnO2ND exhibits high reversible specific capacity of 276 F g-1 at the current density of 0.5 A g-1,as well as excellent rate performance and cycle stability.Then a quasi-solid-state NIC is assembled using multi-walled carbon nanotubes(MWCNTs)as the positive electrode and G/SnO2ND as the negative electrode in a Na-ion conducting gel polymer electrolyte(N-GPE).The obtained NIC shows a maximum energy density of 86 Wh kg-1(at a power density of 955 W kg-1)and a maximum power density of 4100 W kg-1.After 900 charge-discharge cycles,the achieved capacitance retains 95%of its original value at a current density of 0.5 A g-1.Notably,the large-scale production of G/SnO2ND presents a significant step forward in the development of sodium-ion capacitor with low cost,which would provide great attraction for its practical application.