3.E.5.  Artificial Superstructured Optoionic Heterojunction Ion Pump (ASOH-IP) Family

Photoreceptor cells of vertebrates feature ultrastructural membranes interspersed with abundant photosensitive ion pumps to boost signal generation and realize high gain in dim light. Superstructured optoionic heterojunctions (SSOHs) with cation-selective nanochannels have been developed for manipulating photo-driven ion pumping (Liu et al. 2024). A template-directed bottom-up strategy was adopted to sequentially assemble graphene oxide (GO) and PEDOT:PSS into heterogeneous membranes with sculptured superstructures, which feature programmable variation in membrane topography and contain a donor-acceptor interface capable of maintaining electron-hole separation upon photoillumination. Such an elaborate design endows SSOHs with a much higher magnitude of photo-driven ion flux against a concentration gradient in contrast to conventional optoionic membranes with planar configuration. This can be ascribed to the buildup of an enhanced transmembrane potential owing to the effective separation of photogenerated carriers at the heterojunction interface and the increase of energy input from photoillumination due to a synergistic effect of reflection reduction, broad-angle absorption, and wide-waveband absorption. This work unlocks the significance of membrane topographies in photo-driven transmembrane transport and proposes a universal prototype that could be extended to other optoionic membranes to develop high-performance artificial ion pumps for energy conversion and sensing (Liu et al. 2024).