Volume 44, Issue 13 pp. 10926-10936
SHORT COMMUNICATION

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

Muhammad Ali

Muhammad Ali

Center of Research Excellence in Nanotechnology (CENT), King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia

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Nacir Tit

Corresponding Author

Nacir Tit

Physics Department, College of Science, United Arab Emirates University, Al-Ain, United Arab Emirates

Correspondence

Nacir Tit, Physics Department, College of Science, United Arab Emirates University, Al-Ain 15551, United Arab Emirates.

Email: [email protected]

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Zain H. Yamani

Zain H. Yamani

Center of Research Excellence in Nanotechnology (CENT), King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia

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First published: 07 July 2020
Citations: 19

Funding information: UAEU Research Center for Energy and Environment Sciences for financial support, Grant/Award Number: 31R145

Summary

Spin-polarized density functional theory (DFT) is employed to study the adsorption of H2 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 H2 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 H2 molecules. On the other hand, a weaker chemisorption process, associated with weak splitting of H2 molecule, takes place in the case of Pd or Pt dopants. The chemisorption of H2 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 H2 and ZnO-NT.

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