Enhanced H2 sensitivity at room temperature of ZnO nanowires functionalized by Pd nanoparticles

For sensitive detection of H-2, ZnO nanowires networks decorated with photo-decomposed Pd nano-particles were fabricated between femtosecond laser-writing interdigitated electrodes by chemical vapor deposition method. When H-2 concentration is increased from 20 to 4000 ppm at room temperature, sensitivity of the sample is increased from 3.7% to 1017.9%. The high sensitivity can be explained by considering the reaction between the adsorbed O-2(-) and the disassociated H atoms facilitated by Pd nanoparticles. This mechanism is further supported by the H-2 response results under UV light illumination, which can reduce the amount of O-2(-) on the ZnO surface, leading to depressed sensitivity. The sensor also shows high selectivity, long-term stability, and ultra-low power consumption of nanowatt level, due to the novel fabrication process. (C) 2011 American Institute of Physics. [doi:10.1063/1.3647310]