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For the porous‐membrane‐based osmotic energy generator, the potential synergistic enhancement mechanism of various key parameters is still controversial, especially because optimizing the trade‐off between permeability and selectivity is still a challenge. Here, to construct a permeability and selectivity synergistically enhanced osmotic energy generator, the two‐dimensional porous membranes with tunable charge density are prepared by inserting sulfonated polyether sulfone into graphene oxide. Influences of charge density and pore size on the ion transport are explored, and the ionic behaviors in the channel are calculated by numerical simulations. The mechanism of ion transport in the process is studied in depth, and the fundamental principles of energy conversion are revealed. The results demonstrate that charge density and pore size should be matched to construct the optimal ion channel. This collaborative enhancement strategy of permeability and selectivity has significantly improved the output power in osmotic energy generation; compared to the pure graphene oxide membrane, the composite membrane presents almost 20 times improvement. [ABSTRACT FROM AUTHOR]

Abstract For the porous‐membrane‐based osmotic energy generator, the potential synergistic enhancement mechanism of various key parameters is still controversial, especially because optimizing the trade‐off between permeability and selectivity is still a challenge. Here, to construct a permeability and selectivity synergistically enhanced osmotic energy generator, the two‐dimensional porous membranes with tunable charge density are prepared by inserting sulfonated polyether sulfone into graphene oxide. Influences of charge density and pore size on the ion transport are explored, and the ionic behaviors in the channel are calculated by numerical simulations. The mechanism of ion transport in the process is studied in depth, and the fundamental principles of energy conversion are revealed. The results demonstrate that charge density and pore size should be matched to construct the optimal ion channel. This collaborative enhancement strategy of permeability and selectivity has significantly improved the output power in osmotic energy generation; compared to the pure graphene oxide membrane, the composite membrane presents almost 20 times improvement.

The authors report the spontaneous formation of water-soluble chitosan-tartaric acid (CS-TA) spherical particles. Particles are formed by heating chitosan in the presence of tartaric acid under hydrothermal conditions. Tartaric acid serves as an ionic cross-linker, a depolymerizing agent, and a particle stabilizer in aqueous phase. The CS-TA particles exhibit superior colloidal stability at a wide pH range due to their surface charge tunability, which is due to the colocalization of surface hydroxyl, amine, and carboxyl groups. At physiological pH condition, particles have zwitterionic structure as determined by the zeta potential measurements. Still, CS-TA maintains colloidal stability at neutral pH due to the abundance of surface hydroxyl groups. As a proof-of-concept study, the CS-TA particles were labeled with a model insoluble cargo (fluorescein isothiocyanate [FITC]) to demonstrate their capacity for solubilizing hydrophobic drugs. The CS-TA/FITC conjugates were found to remain well dispersed at neutral pH, while maintaining FITC fluorescence properties. [ABSTRACT FROM AUTHOR]

Janus transition-metal dichalcogenide monolayers are artificial materials, where one plane of chalcogen atoms is replaced by chalcogen atoms of a different type. Theory predicts an in-built out-of-plane electric field, giving rise to long-lived, dipolar excitons, while preserving direct-bandgap optical transitions in a uniform potential landscape. Previous Janus studies had broad photoluminescence (>18 meV) spectra obfuscating their specific excitonic origin. Here, we identify the neutral and the negatively charged inter- and intravalley exciton transitions in Janus W Se S monolayers with ∼6 meV optical line widths. We integrate Janus monolayers into vertical heterostructures, allowing doping control. Magneto-optic measurements indicate that monolayer W Se S has a direct bandgap at the K points. Our results pave the way for applications such as nanoscale sensing, which relies on resolving excitonic energy shifts, and the development of Janus-based optoelectronic devices, which requires charge-state control and integration into vertical heterostructures.

Abstract: A crucial pre-requisite for quantum information applications is the ability to produce a scalable quantum system that can be controllably manipulated. We present a technique that promises the practical realization of a scalable system with arrays of gated quantum dots (QDs) emitting at wavelengths suitable for fibre based quantum cryptography. We show how the random nature of the nucleation site for self-assembled QDs can be overcome by a nanotemplate deposition technique such that further processing around these dots can be performed. By knowing exactly where the QD is, we position electrostatic gates around the dot with better than 30nm accuracy. With these gates and a Si n-doped back gate, we demonstrate from both simulation and experiment that we can control the electron number of the dot via vertical electric fields. [Copyright &y& Elsevier]