A Fast Humidity Sensor Based on Li⁺-Doped SnO₂ One-Dimensional Porous Nanofibers.

One-dimensional SnO₂- and Li⁺-doped SnO₂ porous nanofibers were easily fabricated via electrospinning and a subsequent calcination procedure for ultrafast humidity sensing. Different Li dopant concentrations were introduced to investigate the dopant's role in sensing performance. The response properties were studied under different relative humidity levels by both statistic and dynamic tests. The best response was obtained with respect to the optimal doping of Li⁺ into SnO₂ porous nanofibers with a maximum 15 times higher response than that of pristine SnO₂ porous nanofibers, at a relative humidity level of 85%. Most importantly, the ultrafast response and recovery time within 1 s was also obtained with the 1.0 wt % doping of Li⁺ into SnO₂ porous nanofibers at 5 V and at room temperature, benefiting from the co-contributions of Li-doping and the one-dimensional porous structure. This work provides an effective method of developing ultrafast sensors for practical applications-especially fast breathing sensors.