Rapid response for hydrogen detection based on macropore gas diffusion channel of PdO–NiO/porous GaN p-n junctions

It is crucial to the performance of hydrogen sensors that regulate the nano morphology, heterojunction, and atomic doping of gas-sensitive materials. In this work, in-situ USP deposition technology was used to synthesize p-p type PdO–NiO compounds sensitive materials on porous GaN etched via PEC method. The maximum response of PdO–NiO/PGaN for 50 ppm H2 is 3.73, and the response/recovery time are 32 s/41 s, respectively. The improvement of sensitivity is attributed to increase of the specific surface area, the enhancement of adsorbed oxygen, the formation of heterojunctions and the noble-metal catalysis. The mechanism of hydrogen sensing and the formation process of PdO–NiO-GaN heterojunctions have been mentioned as well. In addition, PdO–NiO/PGaN sensing device also shows good selectivity and stability for hydrogen sensitivity.