Ultrasonic-Assisted Synthesis of Layered Core-Shell Ni-MOF Derivatives for Enhanced Hydrogen Sensing

Hydrogen sensing is of great significance for environmental monitoring and safety due to the low explosion limit and high flammability of hydrogen gas. In this work, layered and bulk Ni-MOF precursors are designed and pyrolyzed to obtain Ni-Layer-Pyrolysis and Ni-Bulk-Pyrolysis materials. Structural characterizations reveal that Ni-Layer-Pyrolysis inherits a layered morphology with a core-shell structure, higher graphitization degree, and more uniform active sites compared with its bulk counterpart. Electrochemical studies demonstrate that Ni-Layer-Pyrolysis exhibits lower charge-transfer resistance and higher carrier density, which facilitate efficient electron transport. Gas-sensing tests show that the Ni-Layer-Pyrolysis sensor achieves a low detection limit of 100 ppm, a sensitivity of 6.24 at 8000 ppm H₂. Moreover, it displays excellent selectivity against common interfering gases and outstanding long-term stability over 40 days. These results indicate that the layered structure and core-shell architecture play a decisive role in enhancing sensitivity, selectivity, and durability. This study provides new insights into the design of MOF-derived nanostructures for high-performance hydrogen sensors with practical application potential.