V-ATPase-Inspired Artificially Rectified Nanochannel Ion Pumps Using a TpPa-SO₃/TiO₂-C₃N₄ Membrane

The cation transport pump is a critical process in the realm of organismal energy utilization and acquisition. In this study, a TpPa-SO₃/TiO₂-C₃N₄ nanochannel membrane is fabricated to emulate the energy-consuming ion pump mechanism of V-ATPase. The channels exhibit ion rectification properties, excellent cation selectivity due to negatively charged TpPa-SO₃ groups, while the TiO₂-C₃N₄ heterojunction acted as the light-harnessing component for counter-gradient ion transport, enabling light-driven cation pumping through their synergistic effect. Asymmetric visible light irradiation on one side of the TpPa-SO₃/TiO₂-C₃N₄ nanochannel membrane generates a built-in electric field across the membrane due to the intrinsic photoelectronic properties of TiO₂-C₃N₄, driving cation transport against the concentration gradients and demonstrating an ion-pumping effect. Impressively, the nanochannels can utilize external light energy to generate a chemical potential gradient, enabling an entropy reduction process similar to reverse concentration gradient transport in living organisms. These distinctive ion rectification and pumping properties offer great potential for advancements in ion circuits and energy conversion systems, expanding the frontiers of scientific exploration.