3.9 Proposed reaction mechanism
Based on all the above results, the
charge separation process and proposed mechanism for MCNS-10 was
illustrated in Fig. 9 . Under visible light irradiation, the
excited state of MCS could be quickly produced electron-hole pairs. The
photogenerated electrons of MCS migrate from the VB to CB, and a large
number of holes were accumulated on the VB of MCS.
The strong reductive
Na2S/Na2SO3(0.35M/0.25M) solution was used as
sacrificial reagent could consume holes in the VB of MCS, further
facilitating charge separation. Since MCS had more negative CB level
(-0.85 eV) as compared with the CB potential (-0.6 eV) of
NiSe2, the electrons
transfer from the CB of MCS to the CB of NiSe2 was
driven by the thermodynamic driving force [33]. At the same time, 3D
cubes NiSe2 can provide more reduction sites, causing
H+ to combine with electron to generate
H2.