Reviving Zn0 Dendrites to Electroactive Zn2+ by Mesoporous MXene with Active Edge Sites.

Zinc metal-based aqueous batteries (ZABs) offer a sustainable, affordable, and safe energy storage alternative to lithium, yet inevitable dendrite formation impedes their wide use, especially under long-term and high-rate cycles. How the battery can survive after dendrite formation remains an open question. Here, we pivot from conventional Zn dendrite growth suppression strategies, introducing proactive dendrite-digesting chemistry via a mesoporous Ti3C2 MXene (MesoTi3C2)-wrapped polypropylene separator. Spectroscopic characterizations and electrochemical evaluation demonstrate that MesoTi3C2, acting as an oxidant, can revive the formed dead Zn0 dendrites into electroactive Zn2+ ions through a spontaneous redox process. Density functional theory reveals that the abundant edge-Ti-O sites in our MesoTi3C2 facilitate high oxidizability and electron transfer from Zn0 dendrites compared to their in-plane counterparts. The resultant asymmetrical cell demonstrates remarkable ultralong cycle life of 2200 h at a practical current of 5 mA cm-2 with a low overpotential (<50 mV). The study reveals the unexpected edge effect of mesoporous MXenes and uncovers a new proactive dendrite-digesting chemistry to survive ZABs, albeit with inevitable dendrite formation.

Enzyme-Based Mesoporous Nanomotors with Near-Infrared Optical Brakes.

As one of the most important parameters of the nanomotors' motion, precise speed control of enzyme-based nanomotors is highly desirable in many bioapplications. However, owing to the stable physiological environment, it is still very difficult to in situ manipulate the motion of the enzyme-based nanomotors. Herein, inspired by the brakes on vehicles, the near-infrared (NIR) "optical brakes" are introduced in the glucose-driven enzyme-based mesoporous nanomotors to realize remote speed regulation for the first time. The novel nanomotors are rationally designed and fabricated based on the Janus mesoporous nanostructure, which consists of the SiO2@Au core@shell nanospheres and the enzymes-modified periodic mesoporous organosilicas (PMOs). The nanomotor can be driven by the biofuel of glucose under the catalysis of enzymes (glucose oxidase/catalase) on the PMO domain. Meanwhile, the Au nanoshell at the SiO2@Au domain enables the generation of the local thermal gradient under the NIR light irradiation, driving the nanomotor by thermophoresis. Taking advantage of the unique Janus nanostructure, the directions of the driving force induced by enzyme catalysis and the thermophoretic force induced by NIR photothermal effect are opposite. Therefore, with the NIR optical speed regulators, the glucose-driven nanomotors can achieve remote speed manipulation from 3.46 to 6.49 µm/s (9.9-18.5 body-length/s) at the fixed glucose concentration, even after covering with a biological tissue. As a proof of concept, the cellar uptake of the such mesoporous nanomotors can be remotely regulated (57.5-109 µg/mg), which offers great potential for designing smart active drug delivery systems based on the mesoporous frameworks of this novel nanomotor.

Melt Electrospinning Designs for Nanofiber Fabrication for Different Applications.

Nanofibers have been attracting growing attention owing to their outstanding physicochemical and structural properties as well as diverse and intriguing applications. Electrospinning has been known as a simple, flexible, and multipurpose technique for the fabrication of submicro scale fibers. Throughout the last two decades, numerous investigations have focused on the employment of electrospinning techniques to improve the characteristics of fabricated fibers. This review highlights the state of the art of melt electrospinning and clarifies the major categories based on multitemperature control, gas assist, laser melt, coaxial, and needleless designs. In addition, we represent the effect of melt electrospinning process parameters on the properties of produced fibers. Finally, this review summarizes the challenges and obstacles connected to the melt electrospinning technique.