3.5 UV-vis DRS analysis
As observed in Fig. 6, the optical properties of pristine
ZnCdS nanoparticles,
CoP polyhedrons,
Co3O4 QDs are investigated by the UV-vis
diffuse reflectance spectra (UV-vis DRS). Obviously, UV-vis DRS depict
the fact that the three samples manifest strong visible light
absorption. And original ZnCdS nanoparticles exhibit a light absorption
with an edge of about 560 nm, meaning the significant semiconductor
characteristics. However, the CoP polyhedrons and
Co3O4 QDs exhibit an intense light
absorption from 300 to 800 nm, implying their semi-metallic nature
nature [42,43]. In fact, TMPs have been proved to have semi-metallic
nature and high electrical conductivity. QDs with narrow emission
bandwidth are confined
three-dimensionally. Thus, CoP and Co3O4QDs can serve as electron sink to greatly promote the separation
efficiency of charges from ZnCdS and fundamentally inhibit the
recombination of photo-excited carriers, so as to lead to
highly-efficient hydrogen evolution rate.