Role of defects and dopants in zinc oxide nanotubes for gas sensing and energy storage applications

Summary Spin‐polarized density functional theory (DFT) is employed to study the adsorption of H 2 gas molecules on zinc oxide nanotubes (ZnO‐NTs) with intrinsic defects (oxygen and zinc vacancies) and dopants (Pd and Pt). Results indicate that defects lead to a strong chemisorption process, associated with strong splitting of the H 2 molecule, rendering an irreversible process; that is, desorption is not possible. Such strong chemisorption process results in large adsorption energy and charge transfer between the defective‐ZnO‐NTs and H 2 molecules. On the other hand, a weaker chemisorption process, associated with weak splitting of H 2 molecule, takes place in the case of Pd or Pt dopants. The chemisorption of H 2 on defective sites and dopants changes the energy gap to a large extent, resulting in major changes in the electrical conductivity of the ZnO‐NTs and consequently revealing their relevance for gas sensing applications with an enhancement of sensor response. From a different perspective, Pd ought to be a good dopant for ZnO‐NT based hydrogen storage material as it weakens the adsorption strength between H 2 and ZnO‐NT.