Self-heating hydrogen gas sensor based on an array of single suspended carbon nanowires functionalized with palladium nanoparticles

This study reports the development of a novel hydrogen gas sensor based on an array of single suspended carbon nanowires (diameter ∼200 nm, length ∼100 μm) decorated with Pd nanoparticles (PdNPs) of various sizes for room temperature H2 gas sensing. These sensors provide high sensitivity, a wide sensing range (10 ppm - 5%), and complete gas response recovery in 5 s with ultralow power consumption (30 μW). Such performance is achieved using a novel suspended PdNP/carbon nanowire architecture, which offers enhanced mass transfer, high surface area to volume ratios, and good thermal insulation. This platform can be fabricated using simple batch microfabrication processes including carbon-MEMS and electrodeposition. The sensitivity and range of the sensor can be modulated by controlling Pd nanoparticle sizes (3-5 nm PdNPs: 3.2% ppm−1/2, 10-1000 ppm; 10-15 nm PdNPs: 0.32% ppm−1/2, 700 ppm - 5%). A wide sensing range is achieved by integrating nanowires with various sizes of PdNPs onto a chip. The electrical resistance of a suspended PdNP/carbon nanowire quickly and completely recovers its original state in a very short time via ultralow-power, Joule heat-based self-heating. This enables reproducible and long-term durable gas sensing.