Preparation And Application Of Silver Based Micro And Nanocomposites

Silver-based micro-nano materials are considered to be the most promising functional phase materials of conductive paste because of their excellent electrical conductivity and oxidation resistance.In this paper,silver nanoparticles(Ag NPs)with controllable morphology and particle size were prepared and combined with organic paste to prepare conductive paste with good electrical conductivity and applied to solar cells to improve photovoltaic conversion efficiency.However,as a precious metal,silver has less stock in the world,and the high cost can not meet the needs of photovoltaic development.Therefore,we prepare silver-coated copper powder to replace part of the silver powder so as to reduce the paste cost.In addition,silver and copper have excellent antibacterial activity,so we consider micro-nano silver-coated copper as an antibacterial material and test its antibacterial properties by Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus).This paper mainly explores the preparation and application of silver-based micro-nanocomposites,including the preparation and characterization of silver nanoparticles and silver-coated copper micron particles,the preparation and photovoltaic performance testing of conductive paste,and the antibacterial activity detection of micron silver-coated copper.First,Silver nanoparticles were successfully prepared by liquid phase reduction method and analyzed by X-ray diffractometer(XRD).The morphology and particle size of silver nanoparticles were detected by scanning electron microscope(SEM).Change the reducing agent to adjust the size range of silver nanoparticles to 80-160 nm;,select appropriate surfactants to improve the dispersion of silver powder,and explore the effect of reductant concentration on the electrical conductivity of silver powder.The oxidation resistance of the product was characterized by synchronous thermal analysis(STA),and the electrical conductivity was tested by powder resistance meter.The results show that sodium dodecyl benzene sulfonate can effectively improve the surface charge distribution of silver powder and form a double electric layer on the surface of silver powder,thus effectively reducing the agglomeration of silver nanoparticles.When the reductant concentration is 0.03 mol/L,the silver nanoparticles have good electrical conductivity,sintering properties and oxidation resistance.The resistivity of the silver nanoparticles is 9.8×10-5 Ω·cm,which is 8.3×10-5Ω·cm lower than that of the silver nanoparticles prepared with the reductant concentration of 0.01 mol/L.The resistivity of silver nanoparticles further decreased to 8.5×10-5 Ω·cm after sintering,which shows that silver nanoparticles have good sintering properties.Second,Micron silver-coated copper composite particles(Cu@Ag MPs)were prepared by displacement-reduction method.The core-shell structure was characterized by transmission electron microscopy(TEM),the elements and contents were detected by energy dispersive spectroscopy(EDS),the oxidation resistance of micro-nano silver-coated copper particles was detected by thermogravimetric analysis(TGA),and the specific surface area was measured by specific surface area analyzer(BET).The effect of complexing agent on the morphology of micro-nanometer silver-coated copper particles was investigated,the results showed that using ammonia as complexing agent could effectively promote the deposition of silver on the surface of copper powder,and the effects of temperature,reducing agent and concentration on the morphology and properties of silver-coated copper were investigated.When the temperature increases from 30-60℃,the resistivity of silver-coated copper powder increases,and the resistivity of silver-coated copper powder can be effectively reduced to 1.52×10-4 Ω·cm with sodium dodecyl benzene sulfonate as dispersant.The formation of free silver in the product can be effectively reduced by changing the reductant and concentration,and the micro-nano silver-coated copper particles prepared when the concentration of potassium sodium tartrate is 0.01 mol/L has uniform and dense silver coating and excellent oxidation resistance,and the resistivity is 1.11×10-4Ω·cm lower than that of the micro-nano silver-coated copper particles prepared with potassium sodium tartrate concentration of 0.04 mol/L.Third,to explore the effects of nano-silver content,kinds of organic solvents and micro-nano silver-coated copper content on the performance of conductive paste,prepare conductive paste and apply it to solar cells to detect its conversion rate.The results show that the addition of 24 wt%nano-silver can effectively increase the contact resistance,square resistance and resistivity of silver paste to 0.8×10-2 Ω,1.1×10-5 Ω·cm,1.5×10-2 Ω and increase the conversion efficiency of HJT solar energy to 25.24%.The addition of 26 wt%micro-nano silver-coated copper can reduce the cost of conductive paste by 24%while ensuring its electrical conductivity.The preparation process was optimized,the curing temperature of silver paste was 160℃,and diethylene glycol ethyl ether acetate(DCAC)was used as the organic solvent of silver paste.The conductive paste prepared under these conditions was applied to HJT solar energy,and the conversion efficiency was improved to 25.54%.Fourth,the antimicrobial properties of silver,silver-coated copper and copper were compared by E.coli and S.aureus.According to the results of bacteriostatic zone,the antimicrobial activity of silver-coated copper was better than that of silver and copper,and the minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)of silver-coated copper against the two strains were the smallest,which also proved that its excellent antimicrobial activity,the MIC values against E.coli and S.aureus were 0.781 mg/mL and 3.125 mg/mL,respectively,and the MIC values against MBC E.coli and S.aureus were the same as 6.25 mg/mL.The results of growth curve demonstration that micro-nano silver-coated copper particles can effectively shorten the logarithmic growth period of bacteria and make it enter the stable phase speedily.