Single Nanowire Electrochemical Devices

We report the single nanowire electrode devices designed as a unique platform for in situ probing the intrinsic reason for electrode capacity fading in Li ion based energy storage devices. In this device, a single vanadium oxide nanowire or single Si/a-Si core/shell nanowire was used as working electrode, and electrical transport of the single nanowire was recorded in situ to detect the evolution of the nanowire during charging and discharging. Along with lithium ion intercalation by shallow discharge, the vanadium oxide nanowire conductance was decreased over 2 orders. The conductance change can be restored to previous scale upon lithium ion deintercalation with shallow charge. However, when the nanowire was deeply discharged, the conductance dropped over 5 orders, indicating that permanent structure change happens when too many lithium ions were intercalated into the vanadium oxide layered structures. Different from vanadium oxide, the conductance of a single Si/a-Si core/shell nanowire monotonously decreased along with the electrochemical test, which agrees with Raman mapping of single Si/a-Si nanowire at different charge/discharge states, indicating permanent structure change after lithium ion insertion and extraction. Our present work provides the direct relationship between electrical transport, structure, and electrochemical properties of a single nanowire electrode, which will be a promising and straightforward way for nanoscale battery diagnosis

Multiplexed Free-Standing Nanowire Transistor Bioprobe for Intracellular Recording: A General Fabrication Strategy

Recent advance in free-standing nanowire transistor bioprobes opens up new opportunities of accurately interfacing spatially unobstructed nanoscale sensors with live cells. However, the existing fabrication procedures face efficiency and yield limitations when working with more complex nanoscale building blocks to integrate, for example, multiplexed recordings or additional functionalities. To date, only single-kinked silicon nanowires have been successfully used in such probes. Here we establish a general fabrication strategy to mitigate such limitations with which synthetically designed complex nanoscale building blocks can be readily used without causing significant penalty in yield or fabrication time, and the geometry of the probe can be freely optimized based on the orientation and structure of the building blocks. Using this new fabrication framework, we demonstrate the first multiplexed free-standing bioprobe based on w-shaped silicon kinked nanowires that are synthetically integrated with two nanoscale field-effect transistor devices. Simultaneous recording of intracellular action potentials from both devices have been obtained of a single spontaneously beating cardiomyocyte

Constructing Sub 10 nm Scale Interfused TiO₂/SiO_<i>x</i> Bicontinuous Hybrid with Mutual-Stabilizing Effect for Lithium Storage

TiO2 has been considered as a promising intercalation lithium-ion-battery (LIB) anode material owing to its robust cyclability. However, it suffers from low capacity. Herein, we construct a sub 10 nm scale interfused TiO2/SiOx hybrid with a bicontinuous structure, in which bridged TiO2 nanoparticles (over 80 wt %) are densely packed within a wormlike SiOx network, through the simple oxidation of MAX Ti3SiC2 ceramic. State-of-the-art in situ microscopy characterization unravels a “mutual-stabilizing” effect from the interfused TiO2/SiOx hybrid upon lithiation. That is to say, the two interpenetrated active components restrain the volume expansion of each other with the stress being relieved through abundant interfaces. Meanwhile, the stress generated from one phase functioned as the compressive force on the other phase and vice versa, offsetting the overall volume effect and synergistically reinforcing the structure integrity. Benefiting from the “mutual-stabilizing” effect, the TiO2/SiOx composite manifests a high and stable specific capacity (∼671 mAh g–1 after 580 cycles at 0.1 A g–1) with a low volume expansion of ∼14% even in an extended potential window of 0.01–3.0 V (vs Li+/Li). The concept of mutual-stabilizing effect, in principle, applies to a wide class of interfused bicontinuous hybrids, providing insight into the design of LIB anode materials with high capacity and longevity

Constructing Sub 10 nm Scale Interfused TiO₂/SiO_<i>x</i> Bicontinuous Hybrid with Mutual-Stabilizing Effect for Lithium Storage

TiO2 has been considered as a promising intercalation lithium-ion-battery (LIB) anode material owing to its robust cyclability. However, it suffers from low capacity. Herein, we construct a sub 10 nm scale interfused TiO2/SiOx hybrid with a bicontinuous structure, in which bridged TiO2 nanoparticles (over 80 wt %) are densely packed within a wormlike SiOx network, through the simple oxidation of MAX Ti3SiC2 ceramic. State-of-the-art in situ microscopy characterization unravels a “mutual-stabilizing” effect from the interfused TiO2/SiOx hybrid upon lithiation. That is to say, the two interpenetrated active components restrain the volume expansion of each other with the stress being relieved through abundant interfaces. Meanwhile, the stress generated from one phase functioned as the compressive force on the other phase and vice versa, offsetting the overall volume effect and synergistically reinforcing the structure integrity. Benefiting from the “mutual-stabilizing” effect, the TiO2/SiOx composite manifests a high and stable specific capacity (∼671 mAh g–1 after 580 cycles at 0.1 A g–1) with a low volume expansion of ∼14% even in an extended potential window of 0.01–3.0 V (vs Li+/Li). The concept of mutual-stabilizing effect, in principle, applies to a wide class of interfused bicontinuous hybrids, providing insight into the design of LIB anode materials with high capacity and longevity

Design and Synthesis of Diverse Functional Kinked Nanowire Structures for Nanoelectronic Bioprobes

Functional kinked nanowires (KNWs) represent a new class of nanowire building blocks, in which functional devices, for example, nanoscale field-effect transistors (nanoFETs), are encoded in geometrically controlled nanowire superstructures during synthesis. The bottom-up control of both structure and function of KNWs enables construction of spatially isolated point-like nanoelectronic probes that are especially useful for monitoring biological systems where finely tuned feature size and structure are highly desired. Here we present three new types of functional KNWs including (1) the zero-degree KNW structures with two parallel heavily doped arms of U-shaped structures with a nanoFET at the tip of the “U”, (2) series multiplexed functional KNW integrating multi-nanoFETs along the arm and at the tips of V-shaped structures, and (3) parallel multiplexed KNWs integrating nanoFETs at the two tips of W-shaped structures. First, U-shaped KNWs were synthesized with separations as small as 650 nm between the parallel arms and used to fabricate three-dimensional nanoFET probes at least 3 times smaller than previous V-shaped designs. In addition, multiple nanoFETs were encoded during synthesis in one of the arms/tip of V-shaped and distinct arms/tips of W-shaped KNWs. These new multiplexed KNW structures were structurally verified by optical and electron microscopy of dopant-selective etched samples and electrically characterized using scanning gate microscopy and transport measurements. The facile design and bottom-up synthesis of these diverse functional KNWs provides a growing toolbox of building blocks for fabricating highly compact and multiplexed three-dimensional nanoprobes for applications in life sciences, including intracellular and deep tissue/cell recordings

Ultralong Sb₂Se₃ Nanowire-Based Free-Standing Membrane Anode for Lithium/Sodium Ion Batteries

Metal chalcogenides have emerged as promising anode materials for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). Herein, a free-standing membrane based on ultralong Sb₂Se₃ nanowires has been successfully fabricated via a facile hydrothermal synthesis combined with a subsequent vacuum filtration treatment. The as-achieved free-standing membrane constructed by pure Sb₂Se₃ nanowires exhibits good flexibility and integrity. Meanwhile, we investigate the lithium and sodium storage behavior of the Sb₂Se₃ nanowire-based free-standing membrane. When applied as the anode for LIBs, it delivers a reversible capacity of 614 mA h g^–1 at 100 mA g^–1, maintaining 584 mA h g^–1 after 50 cycles. When applied as the anode for SIBs, it delivers a reversible capacity of 360 mA h g^–1 at 100 mA g^–1, retaining 289 mA h g^–1 after 50 cycles. Such difference in electrochemical performance can be attributed to the more complex sodiation process relative to the corresponding lithiation process. This work may provide insight on developing Sb₂Se₃-based anode materials for high-performance LIBs or SIBs

Encapsulating Nanocrystalline TiO₂ in Nitrogen-Rich Carbon Microspheres for Enhanced Sodium Storage

Sodium-ion batteries (SIBs) are attractive candidates for stationary energy storage. However, most SIB anodes suffer from slow ion diffusion, low capacity, and large volume change. Herein, we encapsulate nanocrystalline TiO2 in nitrogen-doped carbon microspheres (TiO2-MS) with an ultrahigh N content (16.6 wt %) for sodium storage. Ultrahigh N-doping not only introduces rich active sites for sodium storage but also facilitates electron transfer. The anatase nanocrystals dispersed in the N-rich carbon matrix also contribute a certain capacity. The resultant TiO2-MS hybrid delivers a high capacity (390 mAh g–1 at 0.2C) with good durability. In situ and ex situ characterizations reveal that both the adsorption/intercalation of Na+ ions in carbon and the Ti4+/Ti3+ redox of TiO2 are involved in the sodium storage of TiO2-MS

Rational Synthesis of Silver Vanadium Oxides/Polyaniline Triaxial Nanowires with Enhanced Electrochemical Property

We designed and successfully synthesized the silver vanadium oxides/polyaniline (SVO/PANI) triaxial nanowires by combining in situ chemical oxidative polymerization and interfacial redox reaction based on β-AgVO3 nanowires. The β-AgVO3 core and two distinct layers can be clearly observed in single triaxial nanowire. Fourier transformed infrared spectroscopic and energy dispersive X-ray spectroscopic investigations indicate that the outermost layer is PANI and the middle layer is AgxVO(2.5+0.5x) (x + and aniline monomers at the interface. The presence of the Ag particle in a transmission electron microscopy image confirms the occurrence of the redox reaction. The triaxial nanowires exhibit enhanced electrochemical performance. This method is shown to be an effective and facile technique for improving the electrochemical performance and stability of nanowire electrodes for applications in Li ion batteries

Constructing Sub 10 nm Scale Interfused TiO₂/SiO_<i>x</i> Bicontinuous Hybrid with Mutual-Stabilizing Effect for Lithium Storage

TiO2 has been considered as a promising intercalation lithium-ion-battery (LIB) anode material owing to its robust cyclability. However, it suffers from low capacity. Herein, we construct a sub 10 nm scale interfused TiO2/SiOx hybrid with a bicontinuous structure, in which bridged TiO2 nanoparticles (over 80 wt %) are densely packed within a wormlike SiOx network, through the simple oxidation of MAX Ti3SiC2 ceramic. State-of-the-art in situ microscopy characterization unravels a “mutual-stabilizing” effect from the interfused TiO2/SiOx hybrid upon lithiation. That is to say, the two interpenetrated active components restrain the volume expansion of each other with the stress being relieved through abundant interfaces. Meanwhile, the stress generated from one phase functioned as the compressive force on the other phase and vice versa, offsetting the overall volume effect and synergistically reinforcing the structure integrity. Benefiting from the “mutual-stabilizing” effect, the TiO2/SiOx composite manifests a high and stable specific capacity (∼671 mAh g–1 after 580 cycles at 0.1 A g–1) with a low volume expansion of ∼14% even in an extended potential window of 0.01–3.0 V (vs Li+/Li). The concept of mutual-stabilizing effect, in principle, applies to a wide class of interfused bicontinuous hybrids, providing insight into the design of LIB anode materials with high capacity and longevity