3.7 Photophysical and electrochemical properties
In order to further gain some insights into the excellent performance of
bi-heterostructured O/ZCS/P-3 cages,
various electro-/photo-chemical characterizations are carried out as
displayed in Fig. 8. The most accelerated charge migration kinetics in
O/ZCS/P-3 is clearly reflected by
the significantly increased photocurrent response as shown in Fig. 8a.
Moreover, electrochemical impedance spectra (EIS) exhibit that
ITO/O/ZCS/P-3 electrode possesses a
smaller high-frequency semicircle compared with other three electrodes
(Fig. 8b), indicating a lower electron-transport resistance in the
O/ZCS/P-3 material that ensures the faster charge migration. On the
other hand, steady-state photoluminescence (PL) quenching reveals the
most inhibited recombination of light-excited electron-hole pairs in
O/ZCS/P-3 (Fig. 8c). Furthermore, time-resolved photoluminescence (TRPL)
spectroscopy is applied to investigate the charge carrier dynamics of
the as-prepared semiconductors (Fig. 8d). The decay kinetics of
O/ZCS/P-3 exhibits shorter average lifetime (1.62 ns) in comparison with
those of ZCS (1.78 ns), ZCS/CoP (1.75 ns) and ZCS/
Co3O4 QDs (1.70 ns), which signifies the
O/ZCS/P-3 can faster promote the
separation of photo-induced charge carriers. These results verify the
faster separation and migration of light-excited charges in O/ZCS/P-3,
thus leading to the high-performance H2 evolution.