High-performance hydrogen sensor based on an array of single suspended carbon nanowires selectively functionalized with palladium nanoparticles

This paper reports a novel hydrogen sensor based on an array of single suspended carbon nanowires (Φ ~ 200 nm, length ~ 100 μm) decorated with various sizes (10 ~ 50 nm) of Pd nanoparticles; this H2 sensor exhibits advantageous sensor performances such as room temperature sensing with high sensitivity, wide sensing range, and full recovery in 5 s via low power consumption (30 μW). These high performances are enabled by the novel architecture of suspended Pd nanoparticles/carbon nanowires facilitating enhanced mass transfer, high surface area to volume ratio, and good thermal insulation. This novel sensor platform can be fabricated using only simple batch microfabrication processes including carbon-MEMS that consisted UV-lithography and pyrolysis. The sensitivity and sensing range of the H2 sensor can be modulated by controlling the size of Pd nanoparticles (10-30 nm Pd nanoparticles: 2.51%/ppm
^1/2
and 10-7,000 ppm, 30-50 nm Pd nanoparticles: 0.36 %/ppm
^1/2
and 10 ppm-5 %). Hence, wide range of H2 sensing was enabled by integrating nanowires decorated with various Pd nanoparticles on a chip. Moreover, the gas response can be fully recovered in a very short time (e.g. 5 s for 1,000 ppm H2) by self-heating at a carbon nanowire.