A comparative study of H₂ sensing performance of stoichiometric polymorphs of titanium carbide MXenes loaded with Pd...

Although titanium-based MXenes have been widely reported for gas sensing, the effect of crystal stoichiometric variations on the sensing properties has been rarely reported. Herein, stoichiometric polymorphs of titanium carbide MXenes (i.e., Ti₃C₂T and Ti₂CT) loaded with Pd nanodots (NDs) prepared by photochemical reduction were investigated for room-temperature H₂ sensing. Interestingly, we found that Pd/Ti₂CT exhibited greatly enhanced sensitivity to H₂, along with faster response and recovery rates compared to Pd/Ti₃C₂T. The H₂ adsorption induced resistance change in Pd/Ti₂CT was higher than that of Pd/Ti₃C₂T due to the more effective charge transfer at the heterointerface of Pd/Ti₂CT, which was confirmed by shifts of binding energies and theoretical calculation results. We hope this work could be helpful to design more high-performance MXene-based gas sensors.