Gang Bian received his Ph.D. degree in Chemistry from Jiangnan University in 2018. Then he joined the research group of Prof. Jian Zhu as a postdoctoral fellow at Nankai University. He focuses on the development of 2D covalent organic frameworks using solution-based approaches for electronic devices.
Controlled growth of metal–organic frameworks (MOFs) nanocrystals on requisite surfaces is highly desired for myriad applications related to catalysis, energy, and electronics. Here, this challenge is addressed by overlaying arbitrary surfaces with a thermally evaporated metal layer to enable the well‐aligned growth of ultralong quasi‐2D MOF nanoarrays comprising cobalt ions and thiophenedicarboxylate acids. This interfacial engineering approach allows preferred chelation of carboxyl groups in the ligands with the metal interlayers, thereby making possible the fabrication and patterning of MOF nanoarrays on substrates of any materials or morphologies. The MOF nanoarrays grown on porous metal scaffolds demonstrate high electrocatalytic capability for water oxidation, exhibiting a small overpotential of 270 mV at 10 mA cm−2, or 317 mV at 50 mA cm−2 as well as negligible decay of performance within 30 h. The enhanced performance stems from the improved electron and ion transport in the hierarchical porous nanoarrays consisting of in situ formed oxyhydroxide nanosheets in the electrochemical processes. This approach for mediating the growth of MOF nanoarrays can serve as a promising platform for diverse applications.
Understanding the effect of short channels on the performance of fieldeffect transistors (FETs) from emerging low-dimensional semiconductors is crucial to estimate their suitability in high-density integrated circuits. To this end, intricate and costly equipment capable of nanoscale photolithography or e-beam lithography is usually required to fabricate FETs with shrinking channel lengths. Here, the authors propose an economical suspended nanofiber lithography technique with short-channel processing capability, and compatibility with modern semiconductor foundries. By combining the merits of the near-field electrohydrodynamic printing of nanofibers and microscale photolithographic process, the authors successfully fabricate short channels with lengths as small as 48 nm via masks of suspended nanofibers, whose diameters are easily tuned by adjusting the printing conditions. This technique is further applied for exploring the performance of short-channel FETs using semiconductors such as single-walled carbon nanotubes or electrochemically-exfoliated MoS 2 . Their performance is comparable to those made from more demanding lithography methods. This economical nanofabrication technique is promising to be applied on a variety of semiconductors for highly integrated fabrication of submicron short-channel device arrays.
Elastomeric dielectrics are crucial for reliably governing the carrier densities in semiconducting channels during deformation in soft/stretchable field‐effect transistors (FETs). Uncontrolled stacking of polymeric chains renders elastomeric dielectrics poorly insulated at nanoscale thicknesses, thereby thick films are usually required, leading to high voltage or power consumption for on/off operations of FETs. Here, layer‐by‐layer assembly is exploited to build 15‐nm‐thick elastomeric nanodielectrics through alternative adsorption of oppositely charged polyurethanes (PUs) for soft and hysteresis‐free FETs. After mild thermal annealing to heal pinholes, such PU multilayers offer high areal capacitances of 237 nF cm−2 and low leakage current densities of 3.2 × 10−8 A cm−2 at 2 V. Owing to the intrinsic ductility of the elastomeric PUs, the nanofilms possess excellent dielectric properties at a strain of 5% or a bending radius of 1.5 mm, while the wrinkled counterparts show mechanical stability with negligible changes of leakage currents after repeated stretching to a strain of 50%. Besides, these nanodielectrics are immune to high humidity and conserve their properties when immersed into water, despite their assembly occurs aqueously. Furthermore, the PU dielectrics are implemented in carbon nanotube FETs, demonstrating low‐voltage operations (< 1.5 V) and negligible hysteresis without any encapsulations.
Aqueous zinc-ion batteries (ZIBs) have gained wide attention for their low cost, high safety, and environmental friendliness in recent years. β-MnO 2 , a potential cathode material for ZIBs, has been restricted by its small channels for efficient charge storage. Herein, β-MnO 2 nanorods with oxygen vacancies are fabricated by a K + -doping strategy to improve the performance of ZIBs. The assembled batteries exhibit a capacity of 468 mAh g −1 , a power density of 2605 W kg −1 , and an energy density of 179 Wh kg −1 , which outperforms most reported ZIBs. Such a performance is owing to the synergistic combination of the oxygen vacancies in β-MnO 2 and concurrent deposition of ε-MnO 2 from Mn 2+ in the electrolyte. Furthermore, superior cycling stability with negligible capacity decay in these batteries is demonstrated over 1000 cycles at a high current of 2 A g −1 . This study reveals the importance of oxygen vacancies and Mn 2+ deposition effect in understanding the mechanism of charge storage in MnO 2 -based ZIBs.
Microbatteries are indispensable to power emerging miniaturized
electronics for medical, environmental, or stealth applications. However,
they are usually fabricated by additive printing processes, limiting
their sizes and energy densities. Here, we develop a subtractive manufacturing
process by slicing assembled thin-film zinc-ion batteries into microcells
in batches using optimized preintercalated MnO2 (K0.27MnO2·0.54H2O, KMO) as cathodes.
The composite cathode consisting of KMO and reduced graphene oxide
(rGO) delivers a high specific capacity of 323.4 mAh g–1 at 0.1 A g–1 with no capacity loss after 750 cycles
at 1 A g–1. Such a high performance renders Zn//KMO/rGO
solid-state microbatteries with areal energy densities of 0.244 mWh
cm–2, which are comparable to those of the state
of the art. This microbattery, with an area of 4 × 4 mm2 and a thickness of 0.56 mm, can be modularly arranged on a chip
for a stretchable energy-supply circuit, which can be closely attached
to human skin.
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