3.8 Photocatalytic H2 evolution mechanism
Based on the above experimental results, the H2evolution mechanism of the hierarchical
CoP/ZnCdS/Co3O4 QDs bi-heterostructure
cages as a photocatalyst exhibiting ultrahigh hydrogen evolution
activity is depicted as shown in Fig. 9. Under visible light
irradiation, ZnCdS solid solution being inherently active to splitting
of water is excited to generate electrons and holes, and the produced
charges are rapidly captured and transferred by the
excellent-performance CoP and Co3O4 QDs
while the holes on valence band of
ZnCdS react with LA as the
sacrificial reagent, which lead to that the recombination of
electron-hole pairs is greatly inhibited, thereby the high-performance
photocatalytic hydrogen evolution come. In short, the construction of
the bi-heterostructured cages in
CoP/ZnCdS/Co3O4 QDs develops the two
parallel pathways applied to the rapid electron transport, resulting in
the serious improvement of the utilization efficiency of photo-induced
charges on conduction band of ZnCdS for hydrogen evolution.