Figure 5.

(a) Cross‐sectional SEM image of Cu₂S photocathode with FTO/Au/Cu₂S/CdS/TiO₂/RuO_x structure based on Cu₂S thin film prepared from 0.8 m Cu‐S molecular ink. (b) J‐E curves of Cu₂S photocathodes based on Cu₂S thin films under simulated chopped AM1.5 G illumination (100 mW cm⁻²). (c) Incident photon‐to‐current efficiency spectra of the Cu₂S photocathodes at an applied bias of 0 V_RHE under monochromatic illumination. (d) Measured photocurrent density of the Cu₂S photocathode based on Cu₂S thin film prepared from 0.8 m Cu‐S molecular ink under constant bias at 0 V_RHE under simulated AM1.5 G illumination (100 mW cm⁻²). All measurements were performed in 1.0 m phosphate buffer solution (pH 7.0).