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 H2 sensing. Interestingly, we found that Pd/Ti2CTx exhibited greatly enhanced sensitivity to H2, along with faster response and recovery rates compared to Pd/Ti3C2Tx. The H2 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.
The development of catalysts with high atom utilization and activity is the biggest challenge for electrocatalytic hydrodechlorination (EHDC) technology . Herein, a design strategy of TiO 2 @PDA inorganic-organic core-shell skeleton for loading lower dosage of noble palladium (Pd) with robust activity is reported. The self-supported TiO 2 @PDA nanorod arrays provides exposed surface area for anchoring Pd and PDA as interlayer controls the Pd nucleation to form nanodots with high dispersion, realizing high atom utilization. Moreover, the strong interaction between PDA and Pd realizes the coexistence of electron-rich and deficient Pd species with suitable proportion, which facilitate the H* formation and the C-Cl bond activation, respectively, resulting in the promoted activity. The optimal TiO 2 @PDA/Pd electrode exhibits a low dosage of Pd (0.093 mg cm −2 ) and excellent activity for 4-chlorophenol reduction with a mass activity (MA) of 23.96 min −1 g −1 , which is 3.31 times as high as that of TiO 2 /Pd. The design scheme with inorganic-organic core-shell skeleton as support is benefit for developing highly efficient and lower price elctrocatalysts for EHDC.
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