3.4 UV-vis DRS analysis
A comparison of the UV-vis diffuse reflection spectroscopy (DRS) of MCS,
NiSe2, MCNS
composite were displayed in Fig. 4a . Pure
NiSe2 exhibited
high adsorption coefficient throughout in the visible light and near
infrared regions, which was related to the metallic character [33].
The absorption edge of pure MCS solid solution was approximately 560 nm.
With the increasing of NiSe2 amount, the absorption
intensity peak for
composite catalyst
was obviously increased at the 520-800 nm regions, which were ascribed
to intrinsic absorption of NiSe2 and gradual deepening
of the catalyst color. The light absorption efficiency and
photocatalytic performance of composite catalyst were thus vastly
improved [41], which was also one of the most important reasons for
the improved hydrogen production performance of the catalyst. In
addition, Fig. 4b present the corresponding energy band
gaps (Eg) of MCS and
MCNS-10 were estimated by drawing on the Tauc plots of
(ahv)2 versus hv . The corresponding energy band
gap values of MCS and
MCNS-10 were estimated to be 2.26
and 2.2 eV, respectively. It could be seen that the improvement of the
light absorption performance was related to the decrease of the band gap
values.