High durability for PdNi nano-film hydrogen sensor

Abstract

Stability is a critical parameter for hydrogen (H2) sensors. To enhance stability, we investigated the microstructure and morphology of palladium-nickel (PdNi) nano-film H2 sensors under various sputter pressures and annealing temperatures. Our findings indicate that an increase in the work sputtering pressure reduces the energy of the sputtering atom, resulting in the formation of small gaps between the PdNi nanoparticles at a pressure of 5 Pa. Furthermore, compared to the (111) peak position of pure Pd, the lattice constant of the prepared PdNi nano-film is significantly reduced. At 300 °C, the surface grains exhibit tip passivation. We conducted 20 cyclic tests for 1% H2 concentration of PdNi nano-film sensors, and our repeatability tests demonstrate that small cracks between two PdNi nanoparticles effectively alleviate particle expansion caused by H absorption. However, during the cycles of 1% H2 or N2, significant fluctuations were observed in the response resistance (Rs) and recovery resistance (Ra) during the stable phase. As the annealing temperature increases, Ra and Rs fluctuations decrease noticeably. Furthermore, the PdNi nano-film H2 sensor annealed at 300 °C exhibits high stability, relatively high Rs, short response time (trs), and short recovery time (trc).