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Two-dimensional (2D) materials enable vertical field effect transistors (VFETs), which provide an alternative path for scaling down the channels of transistors. The challenge is the short channel effect when the thickness of the 2D channel decreases to ∼10 nm. Here, we show that a VFET with an ultrashort channel can be accomplished by employing a semimetal carbon nanotube (CNT) as a 1D van der Waals (vdW) contact. The CNT-VFETs with 5–10 nm MoS2channels exhibit high on/off ratios exceeding 105, low subthreshold swing values of 160–120 mV/dec, and high current densities over 104A/cm2. Such a switch even works with an ∼ 3.4 nm thick channel. The excellent comprehensive performance can be ascribed to the reduced short channel effect as the sub-2 nm CNT contact has weaker electrostatic screening to the gate, a reduced Fermi level pinning effect, and a highly tunable barrier. The VFETs with 1D vdW contacts hold great promise for ultrascaled transistors and are prospective in future nanoelectronics and nano-optoelectronics.

Heat dissipation is a serious limitation for increasingly miniaturized and functionalized electronics, resulting in the continuous need for developing highly efficient cooling methods. Here, utilizing the strong van der Waals force between super-aligned carbon nanotubes (SACNTs), a self-supported three-dimensional (3D) CNT/CaCl2radiator with a more outstanding cooling performance than Al cooling fins was designed. Unlike the soft CNT sponges, these 3D structures could sustain a high pressure of 4.5 MPa with a small compression of 10% and thus are defined as hard CNT sponges. Hard CNT sponges show a 44.3% higher cooling efficiency than commercial Al cooling fins at a humidity of 50% due to the massive latent heat of water combining with the high thermal conductivity of CNTs and the high emissivity of the composites. The self-adjusting moisture absorption–desorption process could dissipate heat by water evaporation when electronics work at high power and spontaneously absorb moisture to regenerate the sponges at the standby mode of electronics. Besides, hard CNT sponges possess a much lower density (0.98–1.70 g cm–3) than aluminum (2.7 g cm–3). This high-performance cooler provides an alternative thermal management method for electronics.

Thin films with large compressive residual stress and low interface adhesion can buckle and delaminate from relatively rigid substrates, which is a common failure mode of film/substrate interfaces. Current studies mainly focused on the geometry of various buckling patterns and related physical origins based on a static point of view. However, fundamental understanding of dynamic propagation of buckles, particularly for the complicated web buckles, remains challenging. We adopt strained two-dimensional MoS2thin films to study the phenomenon of web buckling because their interface adhesion, namely van der Waals interaction, is naturally low. With a delicately site-controlled initiation, web buckles can be triggered and their dynamic propagation is in situobserved facilely. Finite element modeling shows that the formation of web buckles involves the propagation and multilevel branching of telephone-cord blisters. These buckled semiconducting films can be patterned by spatial confinement and potentially used in diffuse-reflective coatings, microfluidic channels, and hydrogen evolution reaction electrodes. Our work not only reveals the hidden mechanisms and kinematics of propagation of web buckles on rigid substrates but also sheds light on the development of semiconducting devices based on buckling engineering.

Sulfur-porous carbon nanotube (S-PCNT) composites are proposed as cathode materials for advanced lithium–sulfur (Li–S) batteries. Abundant mesopores are introduced to superaligned carbon nanotubes (SACNTs) through controlled oxidation in air to obtain porous carbon nanotubes (PCNTs). Compared to original SACNTs, improved dispersive behavior, enhanced conductivity, and higher mechanical strength are demonstrated in PCNTs. Meanwhile, high flexibility and sufficient intertube interaction are preserved in PCNTs to support binder-free and flexible electrodes. Additionally, several attractive features, including high surface area and abundant adsorption points on tubes, are introduced, which allow high sulfur loading, provide dual protection to sulfur cathode materials, and consequently alleviate the capacity fade especially during slow charge/discharge processes. When used as cathodes for Li–S batteries, a high sulfur loading of 60 wt % is achieved, with excellent reversible capacities of 866 and 526 mAh g–1based on the weights of sulfur and electrode, respectively, after 100 cycles at a slow charge/discharge rate of 0.1C, revealing efficient suppression of polysulfide dissolution. Even with a high sulfur loading of 70 wt %, the S-PCNT composite maintains capacities of 760 and 528 mAh g–1based on the weights of sulfur and electrode, respectively, after 100 cycles at 0.1C, outperforming the current state-of-the-art sulfur cathodes. Improved high-rate capability is also delivered by the S-PCNT composites, revealing their potentials as high-performance carbon–sulfur composite cathodes for Li–S batteries.