Pd-functionalized Ti₃C₂T_x MXenes for realization of flexible, selective, self-heated H₂ sensing

We introduce a simple approach to realize selective H-2 gas sensing using Pd-decoration on Ti3C2Tx MXene. Ti3C2Tx MXene was initially prepared using Ti3AlC2 MAX phase by etching in HF solution and then different amounts of Pd-decoration (1.1, 1.4, 2.3 and 2.6 at%) on Ti3C2Tx MXene were performed using simple reduction of PdCl2 salt. Various characterizations showed that Pd was uniformly dispersed on Ti3C2Tx MXene nanosheets. The sensors were operated at 25 degrees C under a self-heating operation. The sensor with an optimal amount of Pd-decoration (2.3 at%) under an applied voltage of 2 V showed a greater response to H-2 gas, with excellent selectivity. Additionally, the optimal sensor retained its performance even after 1000 times tilting and 5000 times bending, demonstrating its high resistance to flexibility. Enhanced selectivity to H-2 gas was ascribed to the catalytic activity of Pd (adsorption of hydrogen by Pd) and formation of Pd-Ti3C2Tx MXene heterojunctions. This research highlights the possibility of realization of a selective H-2 sensor with good flexibility and workability at 25 degrees C with low power consumption.