Performance enhancement of gas sensing by modification of molybdenum selenide nanosheets with metal nanoparticles

In this paper, nanostructured molybdenum selenide (MoSe₂) with composited phases are synthesized by hydrothermal method, and the products are modified by metal anoparticles to improve the gas sensing performance. Microstructure characterization shows that few layered 1T/2H-MoSe₂nanosheets have been successfully prepared. Both the morphology and component of nanosheets could be tuned by the reaction parameters. It is shown the MoSe₂-based nanomaterials have excellent selectivity to nitrogen dioxide (NO₂) according to gas sensing properties measurement. The sensitivity of 1T/2H-MoSe₂nanosheets modified by Cu nanoparticles is 17.73 (50 ppm NO₂) at the optimal operating temperature, which is the highest compared with other samples. The sensors also exhibit rapid response/recovery time and high stability. The sensing mechanism of MoSe₂nanosheets toward NO₂is investigated based on the first-principles calculation. The results suggest the modification by metal nanoparticles could significantly improve the adsorption energy and charge transfer between gas molecule and MoSe₂. This work demonstrates a promising guidance for the design of new NO₂gas sensing materials and devices.