Flexible nanofiber sensor for low-concentration hydrogen detection.

A palladium nanoparticle-decorated three-dimensional polyacrylonitrile nanofiber network (Pd-PAN) is prepared as a hydrogen sensor by a chemical bath method. A simple low-temperature annealing treatment is adopted to stabilize the active materials and eliminate the zero-drift of the sensor. The prepared Pd-PAN device exhibits stable performance for hydrogen detection with high sensitivity, especially in a low-concentration hydrogen environment. A minimum detectable limitation of 2 ppm is achieved. In addition, an excellent repeatability is confirmed by continuous measurement under 1% hydrogen. Although the response amplitude decreases with the increased temperature from 30 °C to 70 °C, the fast and stable sensitivity demonstrate the excellent environmental adaptivity and device stability. Notably, due to the accelerated diffusion speed under higher testing temperature, the response time and recovery time are shortened. Moreover, the difference of response as low as 0.01% under bending states at 70 °C strongly confirms the robust mechanical flexibility and superior device performance. The systematic measurements demonstrate the promising application of Pd-PAN sensors for low-concentration hydrogen detection.