Synthesis Of Copper-noble Metal Core-shell Nanowires And Their Applications As High Efficient Catalysts For Fuel Cells

With the rapid development of LED,OLED,TV and other electronic technologies,many innovative problems need to be solved.Transparent flexible electrodes with excellent photoelectric and mechanical properties play the key role in these devices.Currently,a lot of energy we used come from oil,natural gas and coal which are non-renewable energy sources.So the research on renewable energy will become particularly important,and the fuel cell in renewable energy will be a very promising technology for future application.Copper nanowires network possesses outstanding optoelectronic and mechanical properties,which make it a potential platform for transparent flexible electrode and fuel cell catalysts.In view of these challenges,this thesis conducts in-depth studies and achieved important results in three aspects:surface modification of copper nanowires,application of copper-based alloy nanowires as transparent electrode of deep ultraviolet LED,and application of copper based precious metal alloy nanowires as fuel cell catalyst.Firstly,the surface modification architecture of Cu-based core-shell nano wires was established.Ultra-high aspect ratio copper nanowires(average diameter of about 20 nm,average length of about 40?m,aspect ratio>2000)are grown by chemical liquid phase method,which show excellent optoelectronic properties(transmittance of more than 85%under 20 ?/sq sheet resistance)and promise the replacement of ITO as a new generation of transparent flexible electrodes.Based on this approach,we propose a one-pot and two-step method successfully realize the shell metal coating.Surface modification of copper nanowires with Ni and Pt could improve the antioxidant ability.Encapsulation of noble metals such as platinum and palladium produces novel electrochemical catalysts.Modification with metals in various work functions for more extensive optoelectronic applications and performance development.Secondly,Cu@Pt-Ni alloy nanowires as high efficient catalysts for direct fuel cells.We mainly studied the catalyst application of direct methanol fuel cell and direct ethanol fuel cell.In the direct methanol fuel cell,the platinum content in the Cu@Pt-Ni alloy nanowires was regulated.The case with 39.5%platinum showed the best catalytic activity.The area catalytic activity was 5.7 times of that of the commercial carbon-loaded platinum,and the mass activity was 2.5 times.In direct ethanol fuel cells,the nanowires containing 10.5%Pt showed the best catalytic activity,with the catalytic activity of 2.3 times of that of the commercial carbon-based Pt catalyst in area and 1.26 times better in mass one.These alloying nanowire catalysts can not only improve the catalytic activity,but also reduce the cost of fuel cell by reducing the use of noble metals.Thirdly,work function tunable Cu@Metal nanowires for Ohmic transparent electrodes in deep ultraviolet LEDs.A one-pot.two-step method was proposed to synthesize core-shell Cu nanowires,which can realize a large range of continuously adjustable work functions from 4.3 eV to 5.6 eV by encapsulating the Cu nanowires with shell metals in different work functions.The C.u@Pt nanowires network with a high work function(5.65 eV)was transferred onto p-type AlGaN.and the ohmic contact with low resistance was successfully achieved under the annealing condition of 800?,which was an important breakthrough in this field.The transparent electrode of the deepultraviolet LED was prepared and applied,and the EL luminescence spectrum of the deep ultraviolet LED at 280 nm was obtained.The turn-on voltage was about 6.5 V and the deep ultraviolet LED chip with front-side emitting was achieved.In this work,several research results of the Cu-based core-shell nanowires pave forward in the field of renewable energy fuel cell as well as the field of transparent electrodes for short wavelength optoelectronic devices.