Palladium nanoparticle-decorated multi-layer Ti₃C₂T_xdual-functioning as a highly sensitive hydrogen gas sensor and hydrogen storage

In this work, palladium nanoparticle (PdNP)-decorated Ti₃C₂T_xMXene (Pd-Ti₃C₂T_x) was synthesized by a simple two-step process. For this, multilayer Ti₃C₂T_xMXene (ML-Ti₃C₂T_x) was first prepared by a selective HF etching technique, and PdNPs were directly grown on the surface of ML-Ti₃C₂T_xflakes using a polyol method. The relative weight fraction of PdNPs to ML-Ti₃C₂T_xwas elaborately controlled to derive the optimal size and distribution of PdNPs, thereby to maximize its performance as a hydrogen sensor. The optimized Pd-Ti₃C₂T_xnanocomposite showed superb hydrogen-sensing capability even at room temperature with sharp, large, reproducible, concentration-dependent, and hydrogen-selective responses. Furthermore, the nanocomposite also unveiled some extent of hydrogen storage capability at room temperature and 77 K, raising a possibility that it can dual-function as a hydrogen sensor and hydrogen storage.