Nanocomposite of TiO2 @ Ni- or Co-doped Graphene Oxide for Efficient Photocatalytic Water Splitting

Document Type : Original Article

Authors

1 Ministry of Electricity and Water, Kuwait, Kuwait, P.O.12010

2 Chemical Engineering Department, Minia University, El-Minia, 61111, Egypt.

3 College of Applied Science, Department of Engineering, Suhar, 331, Oman

4 Nuclear Materials Authority, Maadi Road, Elqattamia, Cairo, Egypt. P.O. 530.

5 Water Pollution Research Department, Environmental Sciences Division, National Research Centre (NRC), 33 El-Behouth St., Dokki, Cairo, Egypt, P.O. 12622.

Abstract

Nanocomposites of TiO2@Ni-doped or Co-doped graphene oxide (GO) have been suceesfully prepared and are employed for photocalytic water splitting. TEM images showed doted nanostructure and scattered-appearance of Co, Ni with and TiO2 nanoparticles on GO sheet. The XRD patterns proved the existence of the crystal planes of Ni, Co and TiO2 nanoparticles on GO. Moreover, the absorption spectrum of the prepared samples showed a better percentage of absorption of the visible light upon introducing of NiO aor CoO. EDX analysis results confirmed the presence of Co, C, O, and Ti elements in the sample. Interestingly, both n-TiO2/p-NiO/GO and n-TiO2/p-CoO/GO heterojunctions photocatalyst improved the photo-catalytic activity for water splitting nonetheless with different mechanisms. The n-TiO2/p-NiO/GO photocatalyst showed a higher hydrogen production rate of 0.3 mmole/min/g than that of n-TiO2/p-CoO/GO. The generated e/h pairs in the TiO2 part of the catalyst is kept through the effect of the electric field formed by the p-NiO/n-TiO2 heterojunction while Co presence narrows the bandgap and promotes both hydrogen evolution reactions at the conduction and valence band of heterojunctions.

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History

  • Receive Date: 17 February 2019
  • Revise Date: 10 March 2019
  • Accept Date: 19 March 2019

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