1 research outputs found
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/cm<sup>2</sup> 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 <4 h of photoelectrochemical stability. These
findings shed new light on the importance of surface passivation of
nanostructured photoelectrodes for photoelectrochemical applications