Crafting charge transfer channels at titanium dioxide (TiO2) based photoanodes remain a pressing bottleneck in solar-to-chemical conversion technology. Despite the tremendous attempts, TiO2 as the promising photoanode material still suffers from sluggish charge transport kinetics. Herein, we propose an assembly strategy that involves the axial coordination grafting metalloporphyrin-based photosensitizer molecules (MP) onto the surface-modified TiO2 nanorods (NRs) photoanode, forming the composite MP/TiO2 NRs photoelectrode. As expected, the resulted unique MPB/TiO2 NRs photoelectrode displays significantly improved photocurrent density as compared to TiO2 NRs alone and MPA/TiO2 NRs photoelectrode. Scanning photoelectrochemical microscopy (SPECM) and intensity modulated photocurrent spectroscopy (IMPS) were employed to systematically evaluate the continuous photoinduced electron transfer (PET) dynamics for MP/TiO2 NRs photoelectrode. According to the data fitting, it is found that the photoelectron transfer rate (keff) constant for the MPB/TiO2 NRs is about 2.6 times higher than that for the pure TiO2 NRs under light irradiation. The high kinetic constant for the MPB/TiO2 NRs was ascribed to that the conjugated molecules MPB of D-A structure can effectively accelerate intramolecular electrons transfer as well as promote electrons taking part in the reduction reaction of I3– to I– in the novel charge transfer channel. The results demonstrated in this study are expected to shed some light on investigating the mechanism in the charge transfer process of artificial photosynthesis and constructing efficient photoelectrodes.
photosensitizer; TiO2 nanorods; Scanning photoelectrochemical microscopy; photoexcited electron transfer
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Sheng-Ya Zhang, Min Yao, Ze Wang, Tian-Jiao Liu, Rong-Fang Zhan, Hui-Qin Ye, Yan-Jun Feng, Xiao-Quan Lu.
Scanning Photoelectrochemical Microscopic Study in Photoinduced Electron Transfer of Supramolecular Sensitizers-TiO2 Thin Films Systems[J]. Journal of Electrochemistry,
Available at: https://jelectrochem.xmu.edu.cn/journal/vol29/iss6/15