Holey engineered 2D ZnO-nanosheets architecture for supersensitive ppm level H2 gas detection at room temperature

Conquering the issue of room temperature H-2 detection at ppm/ppb level and their fundamental sensing mechanism are vitally needed for the development of highly sensitive/selective sensing devices. Herein, a strategy is proposed to synthesize 2D ZnO holey nanosheets by engineering the tunable pore/hole size with controlled oxygen vacancies using the annealing process for H-2 detection at room temperature. 2D ZnO holey nanosheets annealed at 400 degrees C shows a highly porous network owing to its high surface area, more channels for gas diffusion, and mass transport that exhibits improved gas-sensing performance. ZnO@400 sensor exhibits maximum response of similar to 115 (20 times more than ZnO@800 sample) towards 100 ppm of H-2 at room temperature. The sensor response (recovery) times of the order similar to 9(6) secs recorded to be fastest for ZnO@400 sensor as compared to ZnO@600 (similar to 19(13) secs) and ZnO@800 (similar to 27(20) secs) sensor respectively. Further, the ZnO@400 sensor also displays superior repeatability and stability of similar to 97-99% after 45 days. The involved gas sensing mechanism has also been verified by carrying out XPS measurements before and after H-2 exposure at room temperature that helps to complement the theoretical justification about room temperature metallization effect. Thus, 2D ZnO holey nanosheets turn out to be a pivotal strategy to improve the gas sensing performance due to the synergetic effect of highly porous network and large specific surface areas of 2D nanosheets. The present approach proves to be one of the best methodologies to alleviate the restacking issue of the 2D nanosheets by opening up the inaccessible surfaces.

Automated summary

Conquering the challenge of room temperature H-2 detection at ppm/ppb levels is essential for developing highly sensitive/selective sensing devices. By synthesizing 2D ZnO holey nanosheets through controlled oxygen vacancies and annealing, a sensor with improved gas-sensing performance, fast response times, and high stability can be achieved. The unique porous network and large specific surface areas of 2D ZnO holey nanosheets contribute to their superior gas sensing capabilities.