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

ABSTRACT 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 W 18 O 49 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.