Anomalous conductance induced by hydrogen on ZnO and catalyzed ZnO nanoflowers.

In this work, we report on the anomalous conductance induced by hydrogen (H₂) gas on as-grown and gold/palladium (Au/Pd)-catalyzed zinc oxide nanoflowers (ZnO NFs). The catalyzed ZnO NFs exhibited a sharp increase in conductivity on H₂ exposure and the conductance persisted for several hours on removing H₂. This anomalous behavior is in sharp contrast to conventional ZnO-based H₂ gas sensors wherein the conductivity decreases on removing H₂ gas. The as-grown ZnO NF sample showed drastic response to H₂ under UV illumination with its conductivity increasing by almost 500%. We attribute our observation to catalyzed chemidesorption of oxygen from the ZnO lattice. [ABSTRACT FROM AUTHOR]