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 similar to 200 nm, length similar to 100 mu m) decorated with Pd nanoparticles (PdNPs) of various sizes for room temperature H-2 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 mu W). 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.clos