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.