Highly stable flexible transparent electrode via rapid electrodeposition coating of Ag-Au alloy on copper nanowires for bifunctional electrochromic and supercapacitor device

Copper nanowire (CuNW) is one of the most promising materials for next-generation flexible transparent electrodes (FTEs). Currently, large-scale applications of CuNW in FTEs are still hindered by their poor resistance against oxidation, chemical, and electrochemical corrosion. Previous studies mainly focused on solving a single problem, which can hardly overcome these problems simultaneously. Hence, CuNW@alloy core shell network was developed to address these issues concurrently. It was fabricated by co-electrodepositing Ag-Au alloy layer onto CuNW network through the induction of cyanide in the electrolyte. Compared with pristine CuNW network that the electrical resistance increases a magnitude after storing in atmospheric environment for 12 h, the CuNW@alloy network is still stable after 168 h. The conductivity of CuNW@alloy network almost unchanged after 200 s H2O2 corrosion, while the pristine CuNW network loses conductivity quickly within 30 s. Furthermore, CuNW@alloy network keeps intact after anode oxidation in 1 mol/L H2SO4 solution for 1800 s, but the pristine CuNW nearly dissolves less than 10 s. In addition to high stability, excellent optoelectrical performance (14.2 Ohm/sq at a transmittance of 90.1%) and mechanical flexibility (remaining stable after 2000 bending cycles) is also obtained. Based on these advantages, a primary bifunctional device with electrochromic and supercapacitor performance is fabricated by electrochemical polymerizing polyaniline layer onto advanced CuNW@alloy FTEs, which can change colour with different input voltages and store energy simultaneously, demonstrating its potential in next multifunctional flexible electronics.