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Page 14 of 21 Liu et al. Microstructures 2023;3:2023001 https://dx.doi.org/10.20517/microstructures.2022.23

Figure 8. Steady state and time-resolved photoluminescence quenching experiment of InP/ZnS-S QDs (525 nm, 15 min). Static
2+
photoluminescence quenching for InP/ZnS-S QDs in water after addition of different amounts of Ni (A) and H A (B). PL decay curves
2
2+
of InP/ZnS-S QDs after addition of different amounts of Ni (C) and H A (D), respectively [89] .
2
charge transfer is influenced by photogenerated holes .
[95]
Peter et al. characterized the competition between photogenerated carrier transfer and the recombination of
an α-Fe O electrode using photoelectrochemical impedance spectroscopy (PEIS) [96,97] . The variation of EIS
2
3
with electrodes for different layered α-Fe O films was also recorded. The PEIS response of the α-Fe O
3
3
2
2
electrode exhibits characteristic transmission line behavior in the high-frequency part. Peter et al.
speculated that this may be due to the slow hole transport, probably between adjacent surface iron
species [96,97] . Moreover, Peter et al. studied the effects of introducing Mn on the surface carrier dynamics of
[98]
the hematite nanorods through intensity-modulated photocurrent spectroscopy (IMPS) . In contrast to
EIS, IMPS measurements control the intensity of light on the electrode. In IMPS, the upper quadrant
semicircle corresponds to the competition between charge transfer and recombination and the lower
quadrant semicircle corresponds to the RC attenuation of the system [Figure 9]. Compared to the pristine
hematite, the radius of the low-frequency semicircle (upper quadrant) of the Mn-doped hematite decreased
and the hole transfer efficiency improved. The IMPS result revealed that the introduction of Mn not only
[98]
increased the hole transfer rate constant but also reduced the surface recombination rate constant .

In addition, for the development of the PEC performance, understanding the interactions between ions in
the electric double layer and charge carriers is critical. EIS measurements can also be used to study the
surface ion adsorption. Zheng et al. showed that the capacitance at the interface of an InSe/graphene
photoanode and the solution under illumination was ~2.3 times greater than that in the dark . The result
[99]
-
showed an interaction between the photogenerated holes and OH species, which further enhanced the
concertation of OH surface adsorption and improved the PEC performance .
-
[99]