High-reliable ultrathin Ni@ Ag core−shell nanowires for flexible temperature sensors

Silver nanowires (Ag NWs) have been widely applied as flexible transparent electrodes, but their use in temperature sensors has been limited due to rapid surface oxidation. Herein, we develop an electroplating process to prepare Ni@Ag core–shell nanowires. An ultrathin (approximately 4 nm) conformal Ni shell is coated on the surface of Ag NWs, effectively improving the reliability of Ag NWs without significant deterioration in optical-electric performance (before coating Ni: 15.5 Ω/sq. at 87.7 %, after coating Ni: 13.8 Ω/sq. at 84.2 %). Moreover, the flexibility of the Ni@Ag NWs remains comparable to that of bare Ag NWs. Particularly, the Ni@Ag NW nanowires demonstrate a strong stability to resist vulcanization, strong oxidation and chemical corrosion environment environments. In addition, the flexible temperature sensors based on Ni@Ag NWs is proposed, which demonstrates distinct linearity, reliability at different resistances ranging from 1046 Ω to 2232 Ω in the temperature range from 20 °C to 80 °C, and acceptable TCR values (0.00366 ± 0.0001/°C). The precise engineering of core−shell nanostructures provides a simple, low-cost, and scalable approach for the applications of Ag NWs in flexible temperature sensors.