Regulating Chiral Helical Structures in Liquid-Crystalline Block Copolymers with Chiroptical Response by Synergistic Asymmetric Effects

Unraveling the chirality transfer mechanism is the key to governing chiral expression and structure–property relationships and further constructing new chiral functional devices. Herein, we have systematically investigated the chiral assembly, chiral transfer, and modulation of block copolymers (BCPs) at the molecular, supramolecular, liquid-crystalline (LC) phase, and macroscopic morphological levels. It is revealed that the strength of the LC ordering of Azo mesogens, the solvophobic length of core-forming blocks, and the coupling effects between polymer side chains and backbones play important roles in the chiral evolution and shape change. Furthermore, the various morphologies with different shapes were achieved in the chirality transfer process, including spheres, nanofibers (worms and helical nanowires), vesicles, and more complex large compound micelles. The chiroptical response with morphological changes could be controlled by the in situ photoisomerization of the Azo units. This work provides new insights into designing self-assembled systems with tunable chirality and morphology and could advance the understanding of chiral transfer from molecules to polymeric aggregates

Cobalt Molybdenum Oxide Derived High-Performance Electrocatalyst for the Hydrogen Evolution Reaction

The design and synthesis of high-performance hydrogen evolution reaction (HER) catalysts requires an overall consideration of intrinsic activity and number of active sites as well as electric conductivity. We herein report a facile synthesis of a cost-effective catalyst that can simultaneously address these key issues. A cobalt molybdenum oxide hydrate (CoMoO₄·<i>n</i>H₂O) with a 3D hierarchical nanostructure can be readily grown on nickel foam using a hydrothermal method. Calcination treatment of this precursor material under a reductive atmosphere resulted in the formation of Co nanoparticles on the Co₂Mo₃O₈ surface, which worked in concert to act as active sites for the HER. In addition, the resulting Co₂Mo₃O₈ from the dehydration and reduction reactions of CoMoO₄·<i>n</i>H₂O showed remarkable increases in both active surface area and electrical conductivity. As a consequence of these favorable attributes, the catalyst exhibited electrocatalytic performance comparable to that of the commercial Pt/C catalyst for the HER in alkaline solution, which is promising for practical water-splitting applications