Fig. 5.

Detailed characterization of photoelectrochemical response. a Cyclic voltammogram of n⁺p-Si/2 nm Al₂O₃, n⁺p-Si/2 nm Al₂O₃/AgP₂, and n⁺p-Si/5 nm Al₂O₃/AgP₂ in ferri/ferrocyanide redox solution. All measurements were conducted in the simulated light illumination except as marked. b In situ transient absorption spectra of as-prepared samples measured in CO₂-saturated 0.5 M KHCO₃ solution under open-circuit potential. The samples were excited by 450 nm laser with a power of 50 µW.