Preparation Of Metal Hydroxide/Graphene-Based Composite Materials And Their Properties On Electrochemistry

As a two-dimentional layered material, graphene has presented excellent electrical, optical and mechanical properties. Especially, due to the fantastic conductivity, the application of graphene on electrochemisty has attracted a huge amount of interests. Meanwhile, it can be used as a wonderful carrier which dispersed nanoparticles evenly, forming functional composite materials. In our research, we have synthesized a series of composite materials based on graphene, and their applications such as glucose sensor, fuel cell and supercapacitor have been investigated. The specific research is as follows:1. A novel glucose sensor has been constructed based on gold nanoparticles decorated ternary layered double hydroxide/CNTs/graphene composite. CNTs and graphene were introduced to form 3D CNT-G network for enhancing electronic conductivity, the introduction of Au further increased the number of electron hole, LDH mainly provide activesites toward glucose oxidation. The synergistic effects between Au, LDH and carbon materials make it a promising material as a glucose sensor, which showed a high sensitivity of 1989μA·mM-1μcm-2, a wide linear range from 10μM to 6.1mM and a detection limit of 1μM. Moreover, the sensor has shown wonderful anti-interference property, reproducibility, stability and can be applied in practical detection of glucose.2. LDH/G composite has been synthesized using urea as precipitant, and forming spinel/G(NiFe2O4-Co3O4/G) composite by calcining at 600℃ in N2 atmosphere. Moreover, it indicated that graphene can be N-doped by urea. For measuring the OER property, a series of ternary NiCoFe-LDH/G has been prepared before calcining. Comparing the different proportion of Ni,Co and Fe, the composite MMO-Ni1 5C01.sFe/G displayed the best water oxidation activity, for instance, it exhibits the lowest Tafel slope of 64.2mV·dec-1 and the overpotential is 0.33V at 10mA·cm-2. The water oxidation efficiency is in the order of MMO-Ni1.5Co1.5Fe/G> MMO-Nio.6Co2.4Fe/G> MMO-Ni2.4Coo.6Fe/G> MMO-Ni3Fe/G> MMO-Co3Fe/G.3. A typical conductive polymer(polyaniline) has been grown on the surface of the graphene by in situ polymerization and further used as a supporter for double hydroxides(Co(OH)2-Ni(OH)2), then the supercapacitor based on NiCo/PANI/G composite was built by nickle foam as working electrode. The results show that the capacitance of both NiCo/G and PANI/G are less than 100F/g at 1A/g, whereas, due to the synergistic effect, the NiCo/PANI/G composite displayed enhanced capacitance, which can be 1054.3F/g under the same condition. Furthermore, about 87% of the initial capacitance can be retained after testing for 2000 cycles, indicating a high cycling stability.