Tuning the Conduction Band for Interfacial Electron Transfer: Dye-Sensitized SnxTi1-xO2 Photoanodes for Water

Interfacial electron transfer (IET) dynamics in dyesensitized SnxTi1-xO2 (x = 0, 0.25, 0.50, 0.75, and 1) were investigated using ultrafast transient absorption spectroscopy, linear absorption spectroscopy, and DFT calculations. We found that altering the composition of SnxTi1-xO2 allows for monotonic tunability of the conduction band, altering both the driving force for forward IET and the electronic states of the conduction band involved in IET. IET from a prototypical ruthenium(II) polypyridyl dye sensitizer can be tuned by SnxTi1-xO2 by both modulating the absorption spectrum of the adsorbed dye and altering the electron acceptor states in the conduction band. Periodic DFT calculations show that incorporation of Ti d-character in the conduction band plays a crucial role in promoting ultrafast electron injection.

Automated summary

The composition of SnxTi1-xO2 can be adjusted to tune the conduction band, affecting the driving force for forward IET and the electronic states involved. Tuning of IET can be achieved by modulating the absorption spectrum of the adsorbed dye and altering electron acceptor states in the conduction band. Incorporation of Ti d-character in the conduction band is crucial in promoting ultrafast electron injection, as shown by periodic DFT calculations.