Charge transport dynamics of a CHNHCuBrI/TiO heterojunction in aqueous solution under reverse bias.

The photocurrent output of the CHNHCuBrI/TiO heterojunction photoelectrode in an aqueous solution is super stable even after 30 000 s. However, the photocurrent is extremely weak. Intensity-modulated photocurrent spectroscopy revealed that the electron transfer in the CHNHCuBrI/TiO photoelectrode without bias is not sufficiently fast to compete with the charge recombination process due to the short diffusion length (∼23 nm), resulting in a low photocurrent. The charge separation and charge transfer efficiency in the bulk of CHNHCuBrI could be significantly improved under a small reverse electric field (), resulting in an enhanced photocurrent.