Localized Surface Plasmon Resonance Effect for Near Full‐Spectrum Photo‐Enhanced Osmotic Energy Harvesting

Photoresponsive nanofluidics hold great promise for osmotic energy conversion, leveraging the photo-electro-ion transport conversion process. However, conventional semiconductor-based nanofluidics, which only rely on intrinsic interband transition, constrain the absorption range of light for performance enhancements. Here, we have developed a plasmonic semiconductive heterojunction nanofluidics (PSH-NFs) by integrating a W₁₈O₄₉ layer exhibiting strong localized surface plasmon resonance (LSPR), with a hole-trapping Co(OH)₂ layer. The synergy forms a type-II heterojunction, specifically designed for near-full-spectrum light absorption. Under simulated standard sunlight irradiation, the synergistic effect of LSPR-generated hot electrons and separated photogenerated carriers at the heterojunction interface creates a significantly enhanced surface potential gradient, ensuring a high ion selectivity of 0.93. Furthermore, the directional alignment of these photogenerated carrier transport with the diffusion of cation markedly improves interfacial ion transport efficiency, leading to a substantially increased ionic flux, in agreement with theoretical calculations. Consequently, the PSH-NFs deliver a power density of 36.4 W m^-2, which is a 58.3% increase over non-irradiated conditions and surpasses the performance of reported photoresponsive nanofluidics. The generated electricity can be effectively used to power electronic devices via a photoregulated procedure.