No abstract

Summary Inspired by astonishing collective motions and tactic behaviors in nature, here we show phototactic flocking of synthetic photochemical micromotors. When enriched with hydroxyl groups, TiO 2 micromotors can spontaneously gather into flocks in aqueous media through electrolyte diffusiophoresis. Under light irradiation, due to the dominant nonelectrolyte diffusiophoretic interaction resulting from the overlap of asymmetric nonelectrolyte clouds around adjacent individuals, these flocks exhibit intriguing collective behaviors, such as dilatational negative phototaxis, high collective velocity, and adaptive group reconfiguration. Consequently, the micromotor flocks can migrate along pre-designed paths and actively bypass obstacles with reversible dilatation (expansion/contraction) under pulsed light navigation. Furthermore, owing to the enhanced driving force and rapid dilatational area covering, they are able to execute cooperative tasks that single micromotors cannot achieve, such as cooperative large-cargo transport and collective microenvironment mapping. Our discovery would promote the creation of reconfigurable microrobots, active materials, and intelligent synthetic systems.

To address oil spillage and chemical leakage accidents, the development of efficient sorbent materials is of global importance for environment and water source protection. Here we report on a new type of carbon nanofiber (CNF) aerogels as efficient sorbents for oil uptake with high sorption capacity and excellent recyclability. Importantly, the oil uptake ability of the CNF aerogels can be maintained over a wide temperature range, from liquid nitrogen temperature up to ca. 400°C, making them suitable for oil cleanup under harsh conditions. The outstanding sorption performance of CNF aerogels is associated with their unique physical properties, such as low density, high porosity, excellent mechanical stability, high hydrophobicity and superoleophilicity.

Binder-free MXene films comprising Ti3C2Tx nanoflakes in a face-to-face fashion, achieved by a simple dropping-mild baking approach, exhibit high gravimetric capacitances up to 499 F g(-1) with excellent cyclability and rate performances. The entire electrode system including Ni-foam and MXene film shows volumetric capacitances in the range of 84-226 F cm(-3) depending on the loadings of MXene as active material.