Fig. 5: Performances of h-BN/GGFF electrothermal device in atmospheric environment.

a Schematic for the oxidation progresses of GGFF and h-BN/GGFF electrothermal devices. b Simulated resistance network of GGFF electrothermal device composed of a series of resistance modules with resistance of 10 Ω (labeled in black color). One of the resistance modules is set higher (60 Ω, labeled in red color) to simulate defective location. The current flowing direction is along the warp direction of the fabric, as labeled in b. c Simulated electric power distribution of GGFF electrothermal device with the resistance network in b under an input voltage of 40 V. Infrared images of GGFF (d) and h-BN/GGFF (e) electrothermal devices during their failure processes (scale bar, 1 cm). The dashed arrows denote the moving direction of the failure site. The size of GGFF and h-BN/GGFF is 5 × 3 cm². GGFF has graphene thickness of ~1.0 nm, and h-BN/GGFF has graphene and h-BN thickness of ~1.0 nm and ~29.5 nm, respectively. Position evolution (f) and moving velocity (g) of the failure site through the entire failure progress for the samples in d, e. The position of failure site is defined as the distance between the failure site to the “0” mark labeled in d, e, and the moving velocity is calculated as the ratio of the position change of the failure site to the duration of the failure process. h Stable heating durations (at ~500 °C) of h-BN/GGFF electrothermal devices with different h-BN thicknesses. The stable heating duration is defined from the point when the device reaching the saturated heating temperature (T_s), producing the maximum electric heating energy (P₀), to the point when the produced heating energy (P) decreases to 90 %*P₀. h-BN/GGFFs have graphene thickness of ~1.0 nm and h-BN thickness of 0, ~5.4, ~9.6, ~15.3, ~29.5, ~50.4 nm. i Stable heating durations of GGFF and h-BN/GGFF electrothermal devices at different heating temperatures. GGFF has a graphene thickness of ~1.0 nm, and h-BN/GGFF has a graphene and h-BN thickness of ~1.0 nm and ~29.5 nm, respectively. j Infrared image of h-BN/GGFF electrothermal device (with size of 5 × 3 cm²) after bending ~120° at heating temperature of ~500 °C. h-BN/GGFF has graphene and h-BN thickness of ~1.0 nm and ~29.5 nm, respectively. Temperature profiles (k) and magnified view of heating and cooling processes (l) of h-BN/GGFF electrothermal device at different power densities, where T_s is the saturated heating temperature. m Temperature profile of h-BN/GGFF electrothermal device while applying a square wave from 0 to 120 V with period of 1 min for 1000 cycles. The error bars in h, i represent the standard deviations (n = 5).