Heterojunction Synergized Nanofluidic Ionic Diode for High‐Performance Hydrovoltaic Electricity Generation

ABSTRACT Hydrovoltaic electricity generators have emerged as a promising strategy for harvesting low‐grade environmental energy. Yet their output remains limited by inefficient charge separation, hydroxyl‐induced electron trapping, and reverse current loss. Herein, we proposed a heterojunction synergized nanofluidic ionic diode concept to enhance HEG performance. Al‐doped TiO 2 (ATO) was conformally deposited on vertically aligned Si nanowires (SiNWs) via atomic layer deposition to form a SiNWs/ATO heterojunction, where the built‐in electric field facilitates the efficient separation of charge induced by evaporation‐driven capillary flow. Simultaneously, a nanofluidic ionic diode is established between positively charged SiNWs/ATO nanochannels and the negatively charged porous CNT membrane, enabling rectified ion‐selective transport. The synergistic effects of the heterojunction and nanofluidic ionic diode significantly promote both electron–hole separation and anion/cation selective transport. The SiNWs/ATO HEG achieves an updated recorded performance, delivering an open‐circuit voltage of 1.0 V, a short‐circuit current density of 71.0 µA·cm −2 , and a peak power density of 45.8 µW·cm −2 , approximately twice the highest values previously reported for HEGs. This work not only achieves a mechanistic co‐optimization of charge separation and ionic transport induced by evaporation‐driven capillary flow, but also offers a novel design strategy and practical framework to develop high‐performance and durable HEG.