Jin Zhai

Transition state theory effectively describes solute transport in membranes, where molecular‐level mechanisms dictate the energy barriers involved. Based on this theory and insights from natural systems, our study centers on UiO‐66‐NH ₂ , a metal–organic framework (MOF) with specific binding sites for fluoride ions, resembling the structural features of biological fluoride ion channels. Using a secondary solvothermal growth method, we fabricate a dense and continuous polycrystalline UiO‐66‐NH ₂ membrane on an anodic aluminum oxide substrate. This membrane features subangstrom pores (3.12 and 6.28 Å), which precisely sieve fluoride ions by facilitating selective dehydration and binding. Additionally, the high porosity and surface area of the membrane enhance ion flux while maintaining excellent selectivity. The strong Zr–F interactions within the channel play a pivotal role in reducing the activation energy required for F ⁻ transport, resulting in efficient separation compared to other anions, with the F ⁻ /SO ₄ ²⁻ selectivity reaching 169. This work sheds light on the fundamental ion transport mechanisms in subnanochannels and highlights the potential of MOF membranes for advanced ion separation applications.

Development of efficient artificial light-driven ion pumps is crucial for solar energy harvesting, yet remains fundamentally constrained by severe carrier recombination in photoactive materials. To overcome this fundamental limitation, we design a carbon nitride-carbon nanotube composite membrane that utilizes an interfacial Schottky junction for enhanced charge separation. The charge-regulating behavior of Schottky junctions effectively inhibits photoinduced charge recombination, thereby augmenting charge density asymmetry across the membrane. The resulting robust built-in electric field significantly amplifies light-driven force beyond single-component systems. Under 200 mW cm^-2 illumination, the composite membrane demonstrates exceptional ion pumping performance, enabling reverse ion transport against a 2000-fold concentration gradient. Compared to homogeneous carbon nitride membranes, it exhibits a 233% enhancement in gradient tolerance and a 293% increase in power output. This work presents a Schottky junction engineering strategy for high-performance light-driven ion pumps, paving the way for advanced solar energy conversion and optoelectronic applications.

Artificial nanochannels exhibiting rectification functions are highly promising for applications in the field of iontronics. Introducing asymmetric elements into nanochannels to achieve easy‐to‐integrate planar ion diodes remains a challenge. Herein, the fabrication of planar asymmetric ion diodes is reported through laser etching at the tips of triangular MXene‐cellulose nanofiber (CNF) hybrid membranes. The ion rectification performance is systematically optimized by varying membrane dimensions and laser etching parameters, culminating in a high ion rectification ratio of 33.2. Building on this achievement, it demonstrates their utility in iontronic devices. An ion rectifier bridge, fabricated by integrating four such ion diodes, successfully converted alternating current (AC) signals. This research provides a straightforward and feasible approach to manufacturing planar ion diodes and underscores their significant potential for application in ion‐based circuits.

Harnessing renewable energy for green hydrogen production is critical for decarbonization. An ideal, sustainable route involves self‐powered hydrogen production without additional energy input. Here, the osmotic energy between seawater and river water is used to continuously generate electricity to directly produce hydrogen. Efficient hydrogen production is successfully achieved by connecting the osmotic energy device composed of the polyamide acid PAA37 ion selective membrane and the water electrolysis device in series. The PAA37 membrane, featuring engineered sub‐nanometer channels, exhibits an ultra‐high cation transference number (t+ = 0.96). Targeting the critical challenge of scaling up osmotic power generation, the HLZ equation is introduced. It theoretically establishes that the decline in power density under large‐area conditions is primarily attributed to the electrode impedance within the low‐concentration zone. This finding offers a theoretical foundation for guiding the optimization of large‐scale device designs. Consequently, the PAA37 membrane achieves a power density of 6.0 W m ⁻² over a macroscopic area of 3.14 mm ² under a 50‐fold KCl. Furthermore, by stacking 110 RED units in series, a remarkable output voltage of 24.3 V is generated. By arranging this stack in series and parallel, the system successfully powers an electrolyzer for direct hydrogen production.

In recent years, light‐controlled ion transport systems have attracted widespread attention, however, the use of photoresponsive materials suffers from rapid carrier recombination, thermal field limitations, and narrow spectral response, which significantly restricts their performance enhancement in osmotic energy conversion. This study innovatively couples “blue energy” (osmotic energy) with “green energy” (solar energy), assembling graphene oxide/molybdenum disulfide/sulfonated cellulose nanocrystal (GO/ MoS ₂ /CNC) ion‐channel membranes. Under solar irradiation, the energy level difference between MoS ₂ and GO effectively suppresses the recombination of photogenerated carriers, generating more active electrons and significantly enhancing the carrier density, thereby improving the current flux and ion selectivity. Meanwhile, their photothermal effects accelerate ion diffusion rates. The solar‐enhanced osmotic energy conversion system achieves an output power density of 8.74 W m ⁻² , representing a 78.4% enhancement without illumination, and generates an ultrahigh photoresponsive current of 71.5 µA in 1 m KCl solution. This work provides new inspiration for solar‐enhanced ion channel osmotic energy conversion, demonstrating a novel approach to achieving efficient power generation through photo‐electric/thermal effects.

The cation transport pump is a critical process in the realm of organismal energy utilization and acquisition. In this study, a TpPa‐SO ₃ /TiO ₂ ‐C ₃ N ₄ nanochannel membrane is fabricated to emulate the energy‐consuming ion pump mechanism of V‐ATPase. The channels exhibit ion rectification properties, excellent cation selectivity due to negatively charged TpPa‐SO ₃ groups, while the TiO ₂ ‐C ₃ N ₄ heterojunction acted as the light‐harnessing component for counter‐gradient ion transport, enabling light‐driven cation pumping through their synergistic effect. Asymmetric visible light irradiation on one side of the TpPa‐SO ₃ /TiO ₂ ‐C ₃ N ₄ nanochannel membrane generates a built‐in electric field across the membrane due to the intrinsic photoelectronic properties of TiO ₂ ‐C ₃ N ₄ , driving cation transport against the concentration gradients and demonstrating an ion‐pumping effect. Impressively, the nanochannels can utilize external light energy to generate a chemical potential gradient, enabling an entropy reduction process similar to reverse concentration gradient transport in living organisms. These distinctive ion rectification and pumping properties offer great potential for advancements in ion circuits and energy conversion systems, expanding the frontiers of scientific exploration.

The high-efficiency energy conversion process in organisms is usually carried out by organelles, proteins and membrane systems. Inspired by the cellular aerobic respiration process, we present an artificial electricity generation device, aimed at sustainable and efficient energy conversion using biological components, to demonstrate the feasibility of bio-inspired energy generation for renewable energy solutions. This approach bridges biological mechanisms and technology, offering a pathway to sustainable, biocompatible energy sources. The device features a mitochondria anode and oxygen-carrying red blood cells (RBCs) cathode, alongside a sandwich-structured sulfonated poly(ether ether ketone) and polyimide composite nanochannel for efficient proton transportation, mimicking cellular respiration. Achieving significant performance with 40 wt% RBCs, it produced a current density of 6.42 mA cm⁻² and a maximum power density of 1.21 mW cm⁻², maintaining over 50% reactivity after 8 days. This research underscores the potential of bio-inspired systems for advancing sustainable energy technologies.

Nanofluidic membranes are currently being explored as potential candidates for osmotic energy harvesting. However, the development of high‐performance nanofluidic membranes remains a challenge. In this study, the ultrathin MXene membrane (H‐MXM) is prepared by ultrathin slicing and realize the ion horizontal transportation. The H‐MXM membrane, with a thickness of only 3 µm and straight subnanometer channels, exhibits ultrafast ion transport capabilities resembling an “ion freeway”. By mixing artificial seawater and river water, a power output of 93.6 W m⁻² is obtained. Just as cell membranes have an ultrathin thickness that allows for excellent penetration, this straight nanofluidic membrane also possesses an ultrathin structure. This unique feature helps to shorten the ion transport path, leading to an increased ion transport rate and improveS performance in osmotic energy conversion.