Pd decorated TiO2 nanotube array Schottky barrier diodes for efficient hydrogen sensing application.

Well aligned TiO₂ nanotube arrays have been synthesized via electrochemical anodization, and Pd-based nanoparticles (NPs) were decorated by electrodeposition with the aid of UV irradiation. A new back-to-back Schottky barrier diode (SBD) was formed by connecting with Ag–(Pd decorated TiO₂)–Ti. We found that such an SBD sensor has excellent hydrogen (H₂) sensing performances at a working temperature of 80 °C, with a detection limit as low as 1 ppm as well as a quick response time within 10 s at a low bias voltage (0.025 V). I–V curves and electrochemical impedance spectroscopy analysis demonstrate a typical rectification characteristic of SBD as well as a dramatic decrease of the barrier height of SBD during the H₂ sensing process. The high H₂ sensing performance of a Pd-based NP decorated TiO₂ nanotube array film SBD could be attributed to the synergism of the highly ordered nano-porous configurations and the Pd-based NP (with a high catalytic active metallic Pd nanoshell layer) decoration providing the enhancement of H₂ spillover effect (and/or electronic sensitization) related redox processes. [ABSTRACT FROM AUTHOR]