Harnessing Solar-Salinity Synergy with Porphyrin-Based Ionic Covalent-Organic-Framework Membranes for Enhanced Ionic Power Generation

Nature seamlessly integrates multiple functions for energy conversion, utilizing solar energy and salinity gradients as the primary drivers for ionic power generation. The creation of artificial membranes capable of finely controlling ion diffusion within nanoscale channels, driven by diverse forces, remains a challenging endeavor. In this study, we present an innovative approach: an ionic covalent-organic framework (COF) membrane constructed using chromophoric porphyrin units. The incorporation of ionic groups within these nanoconfined channels imparts the membrane with exceptional charge screening capabilities. Moreover, the membrane exhibits photoelectric responsivity, enhancing the ion conductivity upon exposure to light. As a result, this leads to a substantial increase in the output power density. In practical terms, when subjected to a salinity gradient of 0.5/0.01 M NaCl and exposed to light, the device achieved an outstanding peak power density of 18.0 ± 0.9 W m–2, surpassing the commercial benchmark by 3.6-fold. This innovative membrane design not only represents a significant leap forward in materials science but also opens promising avenues for advancing sustainable energy technologies.