Two‐ and Three‐Dimensional Alignment and Patterning of Carbon Nanotubes

Alignment or patterning of carbon nanotubes (CNTs) is particularly important for fabricating functional devices such as field emitters, nanophotonics, nanoelectronics, and ultrahydrophobic materials. This work briefly reviews recent progress on the synthesis of two‐dimensional CNT patterns, and then particularly concentrates on describing the pillar‐shaped fabrication and very interesting patterns of three‐dimensionally aligned CNTs formed by pyrolysis of iron(II ) phthalocyanine. The possible formation mechanism of the structures is discussed. The Figure shows the pillar‐shaped alignment of three‐dimensional CNTs.     

Highly Water‐Stable Lanthanide–Oxalate MOFs with Remarkable Proton Conductivity and Tunable Luminescence

Although proton conductors derived from metal–organic frameworks (MOFs) are highly anticipated for various applications including solid‐state electrolytes, H₂ sensors, and ammonia synthesis, they are facing serious challenges such as poor water stability, fastidious working conditions, and low proton conductivity. Herein, we report two lanthanide–oxalate MOFs that are highly water stable, with so far the highest room‐temperature proton conductivity (3.42 × 10^?3 S cm^?1) under 100% relative humidity (RH) among lanthanide‐based MOFs and, most importantly, luminescent. Moreover, the simultaneous response of both the proton conductivity and luminescence intensity to RH allows the linkage of proton conductivity with luminescence intensity. This way, the electric signal of proton conductivity variation versus RH will be readily translated to optical signal of luminescence intensity, which can be directly visualized by the naked eye. If proper lanthanide ions or even transition‐metal ions are used, the working wavelengths of luminescence emissions can be further extended from visible to near infrared light for even wider‐range applications.     

Patterning Graphene Surfaces with Iron‐Oxide‐Embedded Mesoporous Polypyrrole and Derived N‐Doped Carbon of Tunable Pore Size

This study develops a novel strategy, based on block copolymer self‐assembly in solution, for preparing two‐dimensional (2D) graphene‐based mesoporous nanohybrids with well‐defined large pores of tunable sizes, by employing polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) spherical micelles as the pore‐creating template. The resultant 2D nanohybrids possess a sandwich‐like structure with Fe₂O₃ nanoparticle‐embedded mesoporous polypyrrole (PPy) monolayers grown on both sides of reduced graphene oxide (rGO) nanosheets (denoted as mPPy‐Fe₂O₃@rGO). Serving as supercapacitor electrode materials, the 2D ternary nanohybrids exhibit controllable capacitive performance depending on the pore size, with high capacitance (up to 1006 F/g at 1 A/g), good rate performance (750 F/g at 20 A/g) and excellent cycling stability. Furthermore, the pyrolysis of mPPy‐Fe₂O₃@rGO at 800 °C yields 2D sandwich‐like mesoporous nitrogen‐doped carbon/Fe₃O₄/rGO (mNC‐Fe₃O₄@rGO). The mNC‐Fe₃O₄@rGO nanohybrids with a mean pore size of 12 nm show excellent electrocatalytic activity as an oxygen reduction reaction (ORR) catalyst with a four‐electron transfer nature, a high half‐wave‐potential of +0.84 V and a limiting current density of 5.7 mA/cm², which are well comparable with those of the best commercial Pt/C catalyst. This study takes advantage of block copolymer self‐assembly for the synthesis of 2D multifunctional mesoporous nanohybrids, and helps to understand the control of their structures and electrochemical performance.     

Arbitrarily 3D Configurable Hygroscopic Robots with a Covalent–Noncovalent Interpenetrating Network and Self‐Healing Ability

Soft materials that can reversibly transform shape in response to moisture have applications in diverse areas such as soft robotics and biomedicine. However, the design of a structurally transformable or mechanically self‐healing version of such a humidity‐responsive material, which can arbitrarily change shape and reconfigure its 3D structures remains challenging. Here, by drawing inspiration from a covalent–noncovalent network, an elaborately designed biopolyester is developed that features a simple hygroscopic actuation mechanism, straightforward manufacturability at low ambient temperature (≤35 °C), fast and stable response, robust mechanical properties, and excellent self‐healing ability. Diverse functions derived from various 3D shapes that can grasp, swing, close–open, lift, or transport an object are further demonstrated. This strategy of easy‐to‐process 3D structured self‐healing actuators is expected to combine with other actuation mechanisms to extend new possibilities in diverse practical applications.     

UV–Vis–NIR Full‐Range Responsive Carbon Dots with Large Multiphoton Absorption Cross Sections and Deep‐Red Fluorescence at Nucleoli and In Vivo

Carbon dots (CDs), with excellent optical property and cytocompatibility, are an ideal class of nanomaterials applied in the field of biomedicine. However, the weak response of CDs in the near‐infrared (NIR) region impedes their practical applications. Here, UV–vis–NIR full‐range responsive fluorine and nitrogen doped CDs (N‐CDs‐F) are designed and synthesized that own a favorable donor‐π‐acceptor (D‐π‐A) configuration and exhibit excellent two‐photon (λ_ex = 1060 nm), three‐photon (λ_ex = 1600 nm), and four‐photon (λ_ex = 2000 nm) excitation upconversion fluorescence. D‐π‐A‐conjugated CDs prepared by solvothermal synthesis under the assistance of ammonia fluoride are reported and are endowed with larger multiphoton absorption (MPA) cross sections (3PA: 9.55 × 10^?80 cm⁶ s² photon^?2, 4PA: 6.32 × 10^?80 cm⁸ s³ photon^?3) than conventional organic compounds. Furthermore, the N‐CDs‐F show bright deep‐red to NIR fluorescence both in vitro and in vivo, and can even stain the nucleoli of tumor cells. A plausible mechanism is proposed on the basis of the strong inter‐dot and intra‐dot hydrogen bonds through N? H···F that can facilitate the expanding of conjugated sp² domains, and thus not only result in lower highest occupied molecular orbital‐lowest unoccupied molecular orbital energy level but also larger MPA cross sections than those of undoped CDs.