“…40 M–S curves with a positive slope were measured at pH = 1, using an Ag/AgCl electrode, confirming that all the two prepared hetero-copper iodides are n-type semiconductors. 41,42 Using the standard hydrogen electrode potential at pH = 7 as a reference standard, the flat-band potentials ( E FB ) of CP 1 and solvent-free CP 2 were converted to −0.63 eV and −0.54 eV, respectively (Fig. S5c and d, ESI†), where E FB is approximately equal to E CBM , and the valence bands are +2.05 eV and +1.91 eV, calculated by the equation E g = E VBM − E CBM .…”