Fig. 4: Photoelectrochemical impedance spectroscopy and photocurrent of photoanodes.

a PEIS Nyquist plots for TiO2|-(RuP2+)5,1, TiO2|-(RuP2+)5,2, and TiO2|-(RuP2+)5,3 with 420-nm LED illumination at an intensity of 3.5 mW cm−2. Inset: the equivalent circuit used for data fitting. b Current density-time traces for TiO2|-(RuP2+)5,1 and TiO2|-(RuP2+)5,3 at a constant bias of 0.2 V vs. NHE under illumination (<400 nm, 100 mW cm−2).