Study On The Controlled Fabrication And Properties Of Nanoporous Silver Substrates

We report a rapid and novel controlled method for large-scale fabrication of nanoparticle-built, three-dimensionally, interconnected porous silver thin sheets (PSTS) with bicontinuous open porosity. The effect of different parameters on the morphology and size has been investigated, and the PSTS has been applied as SERS active substrate and supercapacitor electrode.(1) Chemical etching method is used to fabricate porous bulk silver thin sheets (PSTS) built from three-dimensionally interconnected nanoparticles (NPs). The synthesis starts with synthesizing silver sponges via an in situ growth of NPs which assemble into networks. The sponges are pressed into thin sheets before etching in acid. In order to get a homogeneous porous nanostructure, different reaction parameters has been studied. Research find that the optimum product is obtained under 16% nitric acid at room temperature. The optimum product has a continuous network and interconnecting porous structure. The network ligaments consist of nanoparticles with the average size of 72nm while the average pore size is 90.5nm. In addition, we have also discussed the time-dependent nanopore evolution and etching mechanism.(2) Apply the as-synthesized, NPs-built 3D nanoporous round silver plates to the surface enhanced raman scattering technology, and adjust the particle size, surface roughness and pore size. The nanoporous silver plates exhibit high sensitivity for detection of Rhodamine molecules adsorbed on the surface. The detection limit can reach 10-16M, which is two orders lower than the lowest concentration reported ever (10-14M), and the relative standard deviation of the representative peaks is less than 6%, indicating the outstanding sensitivity and reproducibility.(3) Co3O4 was growed onto the surface of the as-synthesized silver plates to form a Ag/Co3O4 composite electrode. The composite has excellent properties in ion diffusion, proton migration and charge transferring. It also has good electrical conductivity and charge storage performance. The PSTS/Co3O4 electrode with optimized Co3O4 covering of the Ag network ligaments exhibits high specific capacitance of 1276 F g-1 at 1 A g-1, which is much higher than previously reported values for pure Co3O4 nanostructures with different shapes, and even higher than those for Ag-Co3O4 composite nanowire array electrodes. The optimal electrode has a superior rate capability (still 986 Fg-1 at 10 Ag-1) and good stability. Long-term cycling ability exhibits that after 2000 cycles, the composite still remains 92% capacitance ability.