Surface Passivation of GaN Nanowires for Enhanced Photoelectrochemical Water-Splitting

Purushothaman Varadhan, Hui-Chun Fu, Davide Priante, Jose Ramon Duran Retamal, Chao Zhao, Mohamed Ebaid, Tien Khee Ng, Idris A. Ajia, Somak Mitra, Iman S. Roqan, Boon S. Ooi, Jr-Hau He

Research output: Contribution to journalArticlepeer-review

111 Scopus citations

Abstract

Hydrogen production via photoelectrochemical water-splitting is a key source of clean and sustainable energy. The use of one-dimensional nanostructures as photoelectrodes is desirable for photoelectrochemical water-splitting applications due to the ultralarge surface areas, lateral carrier extraction schemes, and superior light-harvesting capabilities. However, the unavoidable surface states of nanostructured materials create additional charge carrier trapping centers and energy barriers at the semiconductor-electrolyte interface, which severely reduce the solar-to-hydrogen conversion efficiency. In this work, we address the issue of surface states in GaN nanowire photoelectrodes by employing a simple and low-cost surface treatment method, which utilizes an organic thiol compound (i.e., 1,2-ethanedithiol). The surface-treated photocathode showed an enhanced photocurrent density of −31 mA/cm at −0.2 V versus RHE with an incident photon-to-current conversion efficiency of 18.3%, whereas untreated nanowires yielded only 8.1% efficiency. Furthermore, the surface passivation provides enhanced photoelectrochemical stability as surface-treated nanowires retained ∼80% of their initial photocurrent value and produced 8000 μmol of gas molecules over 55 h at acidic conditions (pH ∼ 0), whereas the untreated nanowires demonstrated only
Original languageEnglish (US)
Pages (from-to)1520-1528
Number of pages9
JournalNano Letters
Volume17
Issue number3
DOIs
StatePublished - Feb 14 2017

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