Pd nanocrystal sensitization two-dimension porous TiO₂ for instantaneous and high efficient H₂ detection

Hydrogen (H₂) molecules are easy to leak during production, storage, transportation and usage. Because of their flammability and explosive nature, quick and reliable dectection of H₂ molecule is of great significance. Herein, an excellent H₂ gas sensor has been realized based on Pd nanocrystal sensitized two-dimensional (2D) porous TiO₂ (Pd/TiO₂). The formation of 2D porous TiO₂ with the removal of graphene oxide template has been monitored by an in-situ transmission electron microscope. It is found that the size of the GO template can be almost completely replicated by 2D TiO₂. The Pd/TiO₂ sensor exhibited an instantaneous response and a satisfactory low detection limit for H₂ detection. These excellent gas-sensing performances (good selectivity, unique linearity response and high stability) can be attributed to the unique 2D porous structure and the synergistic effect between oxidized Pd and TiO₂, including the unique adsorption properties of O₂ or/and H₂ on Pd/TiO₂, the reaction between PdO and H₂ gas, and the regulated depletion layer arising from p-type PdO to n-type TiO₂. This work demonstrates a rational design and synthesis of highly efficient H₂ sensitive materials for energy and manufacturing security.