posted on 2018-07-25, 00:00authored byPerumalswamy
Sekar Parasuraman, Jhih-Hao Ho, Min-Han Lin, Ching-Hwa Ho
Two-dimensional
(2D) semiconductors play a crucial role in high-efficiency
photocatalysts because of their high surface-to-volume ratio. The
surface property is a key part of photocatalysis. In this work, the
enhanced photocatalytic behavior of the layered ReS2 with
optical polarization along the Re4 nano-diamond-chain (DC)
direction (b axis) has been demonstrated. The unpolarized
photoconductivity (PC) response of ReS2 with an applied
bias along the b axis is approximately 1 order higher
than that of the applied bias perpendicular to the b axis. The polarization-dependent PC spectra of E ∥ b also reveal a higher photoresponsivity
with respect to those measured along the E ⊥ b polarization for the layered ReS2. This result
indicates that stronger polarization dipoles as well as a larger amount
of photogenerated carriers and surface states can contribute to the C-plane ReS2 under the illumination of E ∥ b polarized photons. With the
special axial effect, the layered ReS2 2D photocatalyst
shows much faster degradation rates of 5.6 and 12.3 than the other
transition-metal dichalcogenides of TaS2 and MoS2 for the degradation of methylene blue (MNB) solution. For the polarization-dependent
photodegradation test, the degradation rate of illuminated E ∥ b polarized photons is also
approximately 12 times faster than that of the illuminated E ⊥ b polarized light in a 25 μM
MNB solution. The enhanced photocatalytic behavior of ReS2 along the DC also shows a peak photoreponse of ∼25 μV
detected in the polarized photovoltaic spectrum of the 0.5 μM
MNB dye-sensitized solar cell positioned at ∼1.99 eV. The formation
of a nano-DC and a one-layer trigonal crystalline phase is beneficial
for the versatile energy applications of ReS2.