Parallel Aligned Mesopore Arrays in Pyramidal-Shaped Gallium Nitride and Their Photocatalytic Applications

Hee Jun Kim, Joonmo Park, Byeong Uk Ye, Chul Jong Yoo, Jong Lam Lee, Sang Wan Ryu, Heon Lee, Kyoung Jin Choi, Jeong Min Baik

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

Parallel aligned mesopore arrays in pyramidal-shaped GaN are fabricated by using an electrochemical anodic etching technique, followed by inductively coupled plasma etching assisted by SiO2 nanosphere lithography, and used as a promising photoelectrode for solar water oxidation. The parallel alignment of the pores of several tens of micrometers scale in length is achieved by the low applied voltage and prepattern guided anodization. The dry etching of single-layer SiO2 nanosphere-coated GaN produces a pyramidal shape of the GaN, making the pores open at both sides and shortening the escape path of evolved gas bubbles produced inside pores during the water oxidation. The absorption spectra show that the light absorption in the UV range is ∼93% and that there is a red shift in the absorption edge by 30 nm, compared with the flat GaN. It also shows a remarkable enhancement in the photocurrent density by 5.3 times, compared with flat GaN. Further enhancement (∼40%) by the deposition of Ni was observed due to the generation of an electric field, which increases the charge separation ratio.

Original languageEnglish
Pages (from-to)18201-18207
Number of pages7
JournalACS Applied Materials and Interfaces
Volume8
Issue number28
DOIs
Publication statusPublished - 2016 Jul 20

Bibliographical note

Funding Information:
This work was financially supported by the Pioneer Research Center Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT, & Future Planning (NRF-2013M3C1A3063602), by the KIST-UNIST partnership program (1.150091.01/2V04450), and by the 2016 Research Fund (1.160034.01) of UNIST (Ulsan National Institute of Science and Technology).

Keywords

  • electrochemical etching
  • nanosphere-assisted lithography
  • parallel aligned mesopore arrays
  • photocatalytic water-splitting
  • pyramidal-shaped GaN

ASJC Scopus subject areas

  • General Materials Science

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