Facile polyol synthesis of thermally stable AgNi composite nanowires for flexible transparent heater applications

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Silver nanowires (Ag NWs) are considered promising alternatives to indium tin oxide (ITO) for flexible transparent electrodes because of their excellent conductivity and optical transmittance. However, their practical deployment remains limited by poor thermal stability and degradation through surface diffusion and oxidation at elevated temperatures. In this study, Ag Ni composite nanowires were synthesized through a modified polyol process using two different nickel precursors to enhance the structural and thermal robustness of Ag NW networks. Ni(II) acetate increased the Ni content but suppressed anisotropic growth owing to strong ligand coordination, whereas Ni(NO₃)₂·6H₂O enabled uniform incorporation of Ni species into Ag nanowires, yielding thin, high-aspect-ratio structures with diameters of approximately 70 nm. The incorporated Ni acted as a diffusion barrier that effectively hindered Ag surface migration and grain coalescence, maintaining the one-dimensional morphology up to 300 °C, in stark contrast to pure Ag NWs which disintegrated above 200 °C. The resulting Ag Ni composite films exhibited a high optical transmittance of 89.6% and a low sheet resistance of 20 Ω sq. −1 , outperforming pure Ag NW films (85.9%, 35 Ω sq. −1 ). When implemented as flexible transparent heaters, the Ag Ni films demonstrated rapid Joule heating to temperatures above 100 °C at 5 V, complete evaporation of water droplets within 3 min, and stable operation over repeated heating–cooling cycles. These results confirm that the incorporation of Ni significantly improves the electrical, optical, and thermal robustness of Ag NW networks. Overall, this work presents a facile and scalable chemical-solution route for producing thermally stable, optically transparent, and electrically conductive Ag Ni nanowire films, offering strong potential for next-generation flexible electronics and transparent heating applications.