Fig. 6: Gas sensing properties of the Pd-doped rGO/ZnO-SnO2 based sensors.

a Response of all samples at different temperatures to 100 ppm H2; b dynamic response curves of all samples to different concentrations of hydrogen at 380 °C; c transient response curves of all samples to different concentrations of hydrogen at 380 °C; d repeatability of NC3 to 100 ppm H2 at 380 °C.