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.