Pd-functionalized Ti3C2Tx MXenes for realization of flexible, selective, self-heated H2 sensing

We introduce a simple approach to realize selective H2 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 °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 H2 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 H2 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 H2 sensor with good flexibility and workability at 25 °C with low power consumption.