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

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., Ti3C2Tx and Ti2CTx) loaded with Pd nanodots (NDs) prepared by photochemical reduction were investigated for room-temperature H-2 sensing. Interestingly, we found that Pd/Ti2CTx exhibited greatly enhanced sensitivity to H-2, along with faster response and recovery rates compared to Pd/Ti3C2Tx. The H-2 adsorption induced resistance change in Pd/Ti2CTx was higher than that of Pd/Ti3C2Tx due to the more effective charge transfer at the heterointerface of Pd/Ti2CTx, 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.

Automated summary

This study investigated the effect of crystal stoichiometric variations on the gas sensing properties of titanium-based MXenes loaded with Pd nanodots. Pd/Ti2CTx exhibited higher sensitivity to H-2, as well as faster response and recovery rates compared to Pd/Ti3C2Tx. The higher resistance change induced by H-2 adsorption in Pd/Ti2CTx was attributed to more effective charge transfer at the heterointerface of Pd/Ti2CTx.