A resistance-driven H<inf>2</inf> gas sensor: high-entropy alloy nanoparticles decorated 2D MoS<inf>2</inf>

The need to use hydrogen (H2) gas has increasingly become important due to the growing demand for carbon-free energy sources. However, the explosive nature of H2 gas has raised significant safety concerns, driving the development of efficient and reliable detection. Although 2D materials have emerged as promising materials for hydrogen gas sensing applications due to their relatively high sensitivity, the incorporation of other nanomaterials into 2D materials can drastically improve both the selectivity and the sensitivity of sensors. In this work, high-entropy alloy nanoparticles using non-noble metals were used to develop a sensor for H2 gas detection. This chemical sensor was realized by decorating 2D MoS2 surfaces with multicomponent body-centered cubic (BCC) equiatomic Ti-Zr-V-Nb-Hf high-entropy alloy (HEA) nanoparticles. It was selective towards H2, over NH3, H2S, CH4, and C4H10, demonstrating widespread applications of this sensor. To understand the mechanisms behind the abnormal selectivity and sensitivity, density functional theory (DFT) calculations were performed, showing that the HEA nanoparticles can act as a chemical hub for H2 adsorption and dissociation, ultimately improving the performance of 2D material-based gas sensors.