Engineered Band Alignment of Semiconductive Nanofluidics for Photo‐Electro‐Ion Mediated Ultrahigh Osmotic Energy Harvesting

Abstract As the quest for sustainable energy intensifies, semiconductive 2D nanofluidic membranes with engineered bandgaps for harvesting solar energy and ordered nanoconfined lamellar channels for excellent ion transport regulation stand out as viable candidates for osmotic energy conversion. However, the exploitation of the inherent photoelectrical properties of these 2D nanofluidic systems for capturing light and facilitating osmotic energy conversion remains insufficient. Herein, band structure matched asymmetric 2D semiconductive nanofluidic membranes (BMA‐SNMs), consisting of crosslinked graphitic carbon nitride (C‐g‐C 3 N 4 ) and molybdenum disulfide (C‐MoS 2 ), are designed to realize the photo‐electro‐ion mediated osmotic energy conversion. A photoinduced ionic current of 2.55 µA cm −2 emerges with BMA‐SNMs between equal concentration solutions, confirming the photo‐electro‐ion transport conversion effect resulting from the type II band alignment of BMA‐SNMs with light irradiation. The BMA‐SNMs‐based osmotic energy conversion system with photo‐enhanced ion transport can achieve an ultrahigh power density of up to ≈890 W m −2 , representing a 61.5% improvement compared to systems without light illumination. Furthermore, when subjected to a 500‐fold concentration gradient, such as salt lake water flowing into river water, the output power density increases to 8600 W m −2 . These findings anticipate the potential of 2D photoelectric nanofluidic membranes for advanced, high‐performance energy‐harvesting devices.