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Ultralong carbon nanotubes (CNTs) are considered as promising candidates for many cutting-edge applications. However, restricted by the extremely low yields of ultralong CNTs, their practical applications can hardly be realized. Therefore, new methodologies shall be developed to boost the growth efficiency of ultralong CNTs and alleviate their areal density decay at the macroscale level. Herein, a facile, universal, and controllable method for the in situ synthesis of floating bimetallic catalysts (FBCs) is proposed to grow ultralong CNT arrays with high yields and uniformity. Ferrocene and metal acetylacetonates serve as catalyst precursors, affording the successful synthesis of a series of FBCs with controllable compositions. Among these FBCs, the optimized FeCu catalyst increases the areal density of ultralong CNT arrays to a record-breaking value of ≈8100 CNTs mm -1 and exhibits a lifetime 3.40 times longer than that of Fe, thus achieving both high yields and uniformity. A 30-centimeters-long and high-density ultralong CNT array is also successfully grown with the assistance of FeCu catalysts. As evidenced by this kinetic model and molecular dynamics simulations, the introduction of Cu into Fe can simultaneously improve the catalyst fluidity and decrease carbon solubility, and an optimal catalytic performance will be achieved by balancing this tradeoff., (© 2024 Wiley‐VCH GmbH.)

Radiative cooling is a zero-energy technology that enables subambient cooling by emitting heat into outer space (~3 K) through the atmospheric transparent windows. However, existing designs typically focus only on the main atmospheric transparent window (8-13 μm) and ignore another window (16-25 μm), under-exploiting their cooling potential. Here, we show a dual-selective radiative cooling design based on a scalable thermal emitter, which exhibits selective emission in both atmospheric transparent windows and reflection in the remaining mid-infrared and solar wavebands. As a result, the dual-selective thermal emitter exhibits an ultrahigh subambient cooling capacity (~9 °C) under strong sunlight, surpassing existing typical thermal emitters (≥3 °C cooler) and commercial counterparts (as building materials). Furthermore, the dual-selective sample also exhibits high weather resistance and color compatibility, indicating a high practicality. This work provides a scalable and practical radiative cooling design for sustainable thermal management., (© 2024. The Author(s).)

Transition metal oxides (TMOs) are promising inorganic electrochromic materials (ECMs) that can be widely used in electronic displays and adaptive camouflage. However, there are still huge challenges for TMOs to simultaneously achieve multicolor transformation capability and good cycling stability. Herein, we assemble Au-modified (0.01 wt %) V x O 2 x +1 ( x > 2) nanoflowers (Au@V x O 2 x +1 NFs) composed of two-dimensional porous nanosheets containing two valences states of vanadium (V 4+ and V 5+ ). The Au@V x O 2 x +1 NFs exhibits outstanding electrochromic performance with five reversible color transformations (orange, yellow, green, gray, and blue) at a voltage less than 1.5 V and excellent cycling stability (2000 cycles without significant decay). To the best of our knowledge, this is the first time that a single vanadium oxide ECM, rather than a device, realizes five color changes. This work provides a feasible way for the efficient preparation of multicolor electrochromic TMOs. The newly developed Au@V x O 2 x +1 NFs demonstrate the potential application in adaptive camouflage.