Surface Passivation of GaN Nanowires for Enhanced Photoelectrochemical Water-Splitting.
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/cm2at -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 <4 h of photoelectrochemical stability. These findings shed new light on the importance of surface passivation of nanostructured photoelectrodes for photoelectrochemical applications.
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Purushothaman
0000-0001-7304-5734
P
Varadhan
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Hui-Chun
HC
Fu
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Davide
D
Priante
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Jose Ramon Duran
JR
Retamal
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Chao
0000-0002-9582-1068
C
Zhao
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Mohamed
M
Ebaid
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Tien Khee
TK
Ng
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Idirs
I
Ajia
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Somak
S
Mitra
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Iman S
IS
Roqan
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Boon S
BS
Ooi
Electrical Engineering Program and ‡Materials Science and Engineering Program, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
Jr-Hau
0000-0003-1886-9241
JH
He
III-Nitrides; nanowires; photoelectrochemical water-splitting; solar fuel; surface passivation