Fluorescent H-Aggregate Vesicles and Tubes of a Cyanine Dye and Their Potential as Light-Harvesting Antennae.

H-aggregates of π-conjugated dyes are an ordered supramolecular structure. However, the non-fluorescence behavior of H-aggregates greatly limits their potential applications. In this paper, we report the formation of fluorescent H-aggregates with vesicular and tubular morphologies by the self-assembly of 3,3'-diethylthiacarbocyanine iodide (DiSC2(3)) in ammonia/methanol mixtures. The transition from H-aggregate vesicles to H-aggregate tubes can be achieved by increasing the volume fraction of methanol in the mixtures. H-aggregate vesicles and tubes show two blue-shifted absorption bands and strong fluorescence, which result from the inclined arrangement of DiSC2(3) molecules. Furthermore, light-harvesting complexes are formed by adding dopamine (DA)-quinone (acceptor) in synthetic urine with H-aggregate vesicles or tubes. Our results show that H-aggregate tubes are more efficient than H-aggregate vesicles in transferring excited electrons to DA-quinone acceptors.

Semiconducting Polymer Interfaces for Electrochemically Assisted Mercury Remediation.

Nanostructured polymer interfaces can play a key role in addressing urgent challenges in water purification and advanced separations. Conventional technologies for mercury remediation often necessitate large energetic inputs, produce significant secondary waste, or when electrochemical, lead to strong irreversibility. Here, we propose the reversible, electrochemical capture and release of mercury, by modulating interfacial mercury deposition through a sulfur-containing, semiconducting redox polymer. Electrodeposition/stripping of mercury was carried out with a nanostructured poly(3-hexylthiophene-2,5-diyl)-carbon nanotube composite electrode, coated on titanium (P3HT-CNT/Ti). During electrochemical release, mercury was reversibly stripped in a non-acid electrolyte with 12-fold higher release kinetics compared to nonfunctionalized electrodes. In situ optical microscopy confirmed the rapid, reversible nature of the electrodeposition/stripping process with P3HT-CNT/Ti, indicating the key role of redox processes in mediating the mercury phase transition. The polymer-functionalized system exhibited high mercury removal efficiencies (>97%) in real wastewater matrices while bringing the final mercury concentrations down to <2 µg L-1. Moreover, an energy consumption analysis highlighted a 3-fold increase in efficiency with P3HT-CNT/Ti compared to titanium. Our study demonstrates the effectiveness of semiconducting redox polymers for reversible mercury deposition and points to future applications in mediating electrochemical stripping for various environmental applications.

Stabilization of Sn Anode through Structural Reconstruction of a Cu-Sn Intermetallic Coating Layer.

The metallic tin (Sn) anode is a promising candidate for next-generation lithium-ion batteries (LIBs) due to its high theoretical capacity and electrical conductivity. However, Sn suffers from severe mechanical degradation caused by large volume changes during lithiation/delithiation, which leads to a rapid capacity decay for LIBs application. Herein, a Cu-Sn (e.g., Cu3 Sn) intermetallic coating layer (ICL) is rationally designed to stabilize Sn through a structural reconstruction mechanism. The low activity of the Cu-Sn ICL against lithiation/delithiation enables the gradual separation of the metallic Cu phase from the Cu-Sn ICL, which provides a regulatable and appropriate distribution of Cu to buffer volume change of Sn anode. Concurrently, the homogeneous distribution of the separated Sn together with Cu promotes uniform lithiation/delithiation, mitigating the internal stress. In addition, the residual rigid Cu-Sn intermetallic shows terrific mechanical integrity that resists the plastic deformation during the lithiation/delithiation. As a result, the Sn anode enhanced by the Cu-Sn ICL shows a significant improvement in cycling stability with a dramatically reduced capacity decay rate of 0.03% per cycle for 1000 cycles. The structural reconstruction mechanism in this work shines a light on new materials and structural design that can stabilize high-performance and high-volume-change electrodes for rechargeable batteries and beyond.