Chemical and thermal robust tri-layer rGO/Ag NWs/GO composite film for wearable heaters

Nano-sized silver nanowires (Ag NWs) always suffer from chemical and thermal instability for their high surface energy. To address these issues, a tri-layer structure, consisting of reduced graphene oxide (rGO) top-layer, Ag NW mid-layer and graphene oxide (GO) bottom-layer, is designed and fabricated by convenient spray and pressure transfer process. Different with water-soluble GO covered film, the rGO covered tri-layer film shows better chemical stability (1000 s without apparent changes) in stroke-physiological saline solution than pure Ag NW sample (failed after 200 s) and GO/Ag NWs/GO sample (failed after 240 s). The film also exhibits superior stability when heating at 200 degrees C for 30 min and mechanical robust at a bending radius of 3 mm for 1500 cycles. Moreover, the tri-layer film-based heater can reach 148 degrees C with highly thermal stability during cycling heating and long-time working (> 5 h), indicating its possible applications in flexible and wearable electronics.