Pd modified ZnO nanorod based high dynamic range Hydrogen sensor

In this paper we report on a high dynamic range Hydrogen sensor based on surface modified aligned ZnO hexagonal nanorods. ZnO nanorods were deposited by Chemical Bath Deposition (CBD) technique on SiO₂ coated <;100> p-Si substrate. The nanorods having average diameter of 250-300 nm and average length of 400-500 nm is then surface sensitized by Palladium (Pd) nanoparticles. After structural and electrical characterization, both unmodified and surface modified nanorod based sensors were tested for Hydrogen (H₂) detection in the resistive mode with Pd-Ag catalytic electrode. Both types of sensors offered appreciably high dynamic range (100ppm-20000ppm) at their respective operating temperature of 200°C and 150°C with corresponding response magnitude of ~76% and ~88%. Apart from improvement in response magnitude and reduction in the optimum operating temperature, the surface modification of nanorod also offered significant improvement (faster) in response time and recovery time. The high dynamic range of sensing (H₂) makes this sensor useful for wide range of applications starting from domestic to commercial appliances.