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1.
Adv Mater ; : e2105951, 2021 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-34617348

RESUMO

Zn metal anode has garnered growing scientific and industrial interest owing to its appropriate redox potential, low cost, and high safety. Nevertheless, the instability of Zn anode caused by dendrite formation, hydrogen evolution, and side reactions has greatly hampered its commercialization. Herein, an in situ grown ZnSe overlayer is crafted over one side of commercial Zn foil via chemical vapor deposition in a scalable manner, aiming to achieve optimized electrolyte/Zn interfaces with large-scale viability. Impressively, thus-derived ZnSe coating functions as a cultivator to guide oriented growth of Zn (002) plane at the infancy stage of stripping/plating cycles, thereby inhibiting the formation of Zn dendrites and the occurrence of side reactions. As a result, high cyclic stability (1530 h at 1.0 mA cm-2 /1.0 mAh cm-2 ; 172 h at 30.0 mA cm-2 /10.0 mAh cm-2 ) in symmetric cells is harvested. Meanwhile, when paired with V2 O5 based cathode, assembled full cell achieves an outstanding capacity (194.5 mAh g-1 ) and elongated lifespan (a capacity retention of 84% after 1000 cycles) at 5.0 A g-1 . The reversible Zn anode enabled by the interfacial manipulation strategy via ZnSe cultivator is anticipated to satisfy the demand of commercial use.

2.
Mater Horiz ; 2021 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-34586118

RESUMO

Recent advances in wearable and implantable electronics have increased the demand for biocompatible integrated energy storage systems. Conducting polymers, such as polyaniline (PANi), have been suggested as promising electrode materials for flexible biocompatible energy storage systems, based on their intrinsic structural flexibility and potential polymer chain compatibility with biological interfaces. However, due to structural disorder triggering insufficient electronic conductivity and moderate electrochemical stability, PANi still cannot fully satisfy the requirements for flexible and biocompatible energy storage systems. Herein, we report a biocompatible physiological electrolyte activated flexible supercapacitor encompassing crystalline tetra-aniline (c-TANi) as the active electrode material, which significantly enhances the specific capacitance and electrochemical cycling stability with chloride electrochemical interactions. The crystallization of TANi endows it with sufficient electronic conductivity (8.37 S cm-1) and a unique Cl- dominated redox charge storage mechanism. Notably, a fully self-healable and biocompatible supercapacitor has been assembled by incorporating polyethylene glycol (PEG) with c-TANi as a self-healable electrode and a ferric-ion cross-linked sodium polyacrylate (Fe3+-PANa)/0.9 wt% NaCl as a gel electrolyte. The as-prepared device exhibits a remarkable capacitance retention even after multiple cut/healing cycles. With these attractive features, the c-TANi electrode presents a promising approach to meeting the power requirements for wearable or implantable electronics.

3.
Adv Mater ; 33(43): e2103050, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34463382

RESUMO

Lithium-sulfur (Li-S) batteries are promising candidates for next-generation energy storage, yet they are plagued by the notorious polysulfide shuttle effect and sluggish redox kinetics. While rationally designed redox mediators can facilitate polysulfide conversion, favorable bidirectional sulfur electrocatalysis remains a formidable challenge. Herein, selective dual-defect engineering (i.e., introducing both N-doping and Se-vacancies) of a common MoSe2 electrocatalyst is used to manipulate the bidirectional Li2 S redox. Systematic theoretical prediction and detailed electrokinetic analysis reveal the selective electrocatalytic effect of the two types of defects, thereby achieving a deeper mechanistic understanding of the bidirectional sulfur electrochemistry. The Li-S battery using this electrocatalyst exhibits excellent cyclability, with a low capacity decay rate of 0.04% per cycle over 1000 cycles at 2.0 C. More impressively, the potential for practical applications is highlighted by a high areal capacity (7.3 mAh cm-2 ) and the construction of a flexible pouch cell. Such selective electrocatalysis created by dual-defect engineering is an appealing approach toward working Li-S systems.

4.
Angew Chem Int Ed Engl ; 60(46): 24558-24565, 2021 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-34435420

RESUMO

Witnessing compositional evolution and identifying the catalytically active moiety of electrocatalysts is of paramount importance in Li-S chemistry. Nevertheless, this field remains elusive. We report the scalable salt-templated synthesis of Se-vacancy-incorporated MoSe2 architecture (SeVs-MoSe2 ) and reveal the phase evolution of the defective precatalyst in working Li-S batteries. The interaction between lithium polysulfides and SeVs-MoSe2 is probed to induce the transformation from SeVs-MoSe2 to MoSeS. Furthermore, operando Raman spectroscopy and ex situ X-ray diffraction measurements in combination with theoretical simulations verify that the effectual MoSeS catalyst could help promote conversion of Li2 S2 to Li2 S, thereby boosting the capacity performance. The Li-S battery accordingly exhibits a satisfactory rate and cycling capability even with and elevated sulfur loading and lean electrolyte conditions (7.67 mg cm-2 ; 4.0 µL mg-1 S ). This work elucidates the design strategies and catalytic mechanisms of efficient electrocatalysts bearing defects.

5.
Nano Lett ; 21(1): 203-208, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33372783

RESUMO

For the interlayer dielectric in microelectronics, light element compounds are preferably accepted due to less electronic polarization. Here, the nontrivial dielectric nature of the Sb4O6 cage-molecular crystal, known as α-antimony trioxide (α-Sb2O3), is reported. The gas-phase synthesized α-Sb2O3 nanoflakes are of high crystal quality, from which the abnormal local admittance responses were revealed by scanning microwave impedance microscopy (sMIM). The remarkably low dielectric constant (k), 2.0∼2.5, is corroborated by the analysis of the thickness-dependent sMIM-capacitance signal. In light of the theoretical calculations, the ultralow molecular density and the significantly suppressed ionic polarization are both crucial to the highly reduced k. Combining with the excellent optical band gap, thermal stability, and breakdown strength, α-Sb2O3 is a promising low k dielectric.

6.
Nanoscale ; 10(1): 142-149, 2017 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-29159329

RESUMO

Plasmonic nanomaterials, along with their assemblies, provide numerous applications due to their profound optical properties. In this work, we report the self-assembly of Au@Ag core-shell nanocuboids (NCs) into staircase superstructures in both vertical and horizontal orientations through two-stage droplet evaporation. Each stair is composed of a uniform well-aligned monolayer of NCs. The gap distance between NCs can be greatly shrunk to boost the corresponding surface-enhanced Raman scattering (SERS) performance using an ethanol wash method. The SERS performance of the assembled NCs is calculated by finite-difference time-domain (FDTD) simulation, and studied against the step number using 4-mercaptobenzoic acid as a Raman reporter molecule. The increasing EF with the increase of layer number proves that the plasmon mode propagates well in our uniformly aligned assemblies.

7.
Sci Rep ; 6: 32724, 2016 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-27601199

RESUMO

Using the ultrafast pump-probe transient absorption spectroscopy, the femtosecond-resolved plasmon-exciton interaction of graphene-Ag nanowire hybrids is experimentally investigated, in the VIS-NIR region. The plasmonic lifetime of Ag nanowire is about 150 ± 7 femtosecond (fs). For a single layer of graphene, the fast dynamic process at 275 ± 77 fs is due to the excitation of graphene excitons, and the slow process at 1.4 ± 0.3 picosecond (ps) is due to the plasmonic hot electron interaction with phonons of graphene. For the graphene-Ag nanowire hybrids, the time scale of the plasmon-induced hot electron transferring to graphene is 534 ± 108 fs, and the metal plasmon enhanced graphene plasmon is about 3.2 ± 0.8 ps in the VIS region. The graphene-Ag nanowire hybrids can be used for plasmon-driven chemical reactions. This graphene-mediated surface-enhanced Raman scattering substrate significantly increases the probability and efficiency of surface catalytic reactions co-driven by graphene-Ag nanowire hybridization, in comparison with reactions individually driven by monolayer graphene or single Ag nanowire. This implies that the graphene-Ag nanowire hybrids can not only lead to a significant accumulation of high-density hot electrons, but also significantly increase the plasmon-to-electron conversion efficiency, due to strong plasmon-exciton coupling.

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