Ultrafast H2 gas nanosensor for ppb-level H2 gas detection based on GaN honeycomb nanonetwork

•Employment of GaN honeycomb nanonetwork for the FET type H2 gas sensor.•Demonstration of a H2 sensor with small LOD ∼34 ppb and fast response ∼3 s.•Employment of Pt nanonetwork as the catalyst for H2 gas dissociation.•First discovery of electron tunneling effect during H2 gas detection.