Flexible Carbon Dots‐Intercalated MXene Film Electrode with Outstanding Volumetric Performance for Supercapacitors

Advanced Functional Materials, Journal Year: 2022, Volume and Issue: 33(1)

Published: Oct. 28, 2022

Abstract 2D MXenes have emerged as promising supercapacitor electrode materials due to their metallic conductivity, pseudo‐capacitive mechanism, and high density. However, layer‐restacking is a bottleneck that restrains ionic kinetics active site exposure. Herein, carbon dots‐intercalated strategy proposed fabricate flexible MXene film electrodes with both large ion‐accessible surfaces density through gelation of calcium alginate (CA) within the nanosheets followed by carbonization. The formation CA hydrogel accompanied evaporative drying endow MXene/CA In carbonization process, CA‐derived dots can intercalate into nanosheets, increasing interlayer spacing promoting electrolytic diffusion inside film. Consequently, films exhibit volumetric capacitance (1244.6 F cm −3 at 1 A g −1 ), superior rate capability (662.5 1000 excellent cycling stability (93.5% retention after 30 000 cycles) in 3 m H 2 SO 4 . Additionally, an all‐solid‐state symmetric based on achieves energy 27.2 Wh L This study provides simple yet efficient construct high‐volumetric performance for advanced supercapacitors.

Language: Английский

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Nanoconfined and in Situ Catalyzed MgH₂ Self-Assembled on 3D Ti₃C₂ MXene Folded Nanosheets with Enhanced Hydrogen Sorption Performances

ACS Nano, Journal Year: 2021, Volume and Issue: 15(11), P. 18494 - 18504

Published: Oct. 26, 2021

MXenes are considered as potential support materials for nanoconfinement of MgH2/Mg to improve the hydrogen storage properties. However, it has never been realized so far due stacking and oxidation problems caused by unexpected surface terminations (-OH, -O, etc.) on MXenes. In this study, hexadecyl trimethylammonium bromide was used build a 3D Ti3C2Tx architecture folded nanosheets reduce risk flakes, bottom-up self-assembly strategy successfully applied synthesize ultradispersed MgH2 nanoparticles anchored annealed (Ti-MX). The composite with 60 wt % loading NPs, 60MgH2@Ti-MX, starts decompose at 140 °C is capable releasing 3.0 H2 150 within 2.5 h. addition, reversible capacity up 4.0 still maintained after cycles 200 without obvious loss in kinetics. situ high-resolution TEM observations decomposition process together other analyses revealed that nanosize effect multiphasic interfaces between MgH2(Mg) Ti-MX, especially formed catalytic TiH2, were main reasons accounting superior sorption performances.

Language: Английский

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Dual-Redox-Sites Enable Two-Dimensional Conjugated Metal–Organic Frameworks with Large Pseudocapacitance and Wide Potential Window

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(27), P. 10168 - 10176

Published: June 29, 2021

Advanced supercapacitor electrodes require the development of materials with dense redox sites embedded into conductive and porous skeletons. Two-dimensional (2D) conjugated metal–organic frameworks (c-MOFs) are attractive electrode due to their high intrinsic electrical conductivities, large specific surface areas, quasi-one-dimensional aligned pore arrays. However, reported 2D c-MOFs still suffer from unsatisfying capacitances narrow potential windows because redox-inactive building blocks lead low redox-site densities c-MOFs. Herein, we demonstrate dual-redox-site copper phthalocyanine linked by metal-bis(iminobenzosemiquinoid) (M2[CuPc(NH)8], M = Ni or Cu), which depict both wide windows. Experimental results accompanied theoretical calculations verify that monomers linkages serve as respective for pseudocapacitive cation (Na+) anion (SO42–) storage, enabling continuous Faradaic reactions M2[CuPc(NH)8] occurring in a window −0.8 0.8 V vs Ag/AgCl (3 KCl). The decent conductivity (0.8 S m–1) active-site density further endow Ni2[CuPc(NH)8] remarkable capacitance (400 F g–1 at 0.5 A g–1) excellent rate capability (183 20 g–1). Quasi-solid-state symmetric supercapacitors assembled practical application electrode, deliver state-of-the-art energy 51.6 Wh kg–1 peak power 32.1 kW kg–1.

Language: Английский

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Flexible MXene Framework as a Fast Electron/Potassium‐Ion Dual‐Function Conductor Boosting Stable Potassium Storage in Graphite Electrodes

Advanced Functional Materials, Journal Year: 2021, Volume and Issue: 31(32)

Published: June 1, 2021

Abstract Graphite anodes show great potential for potassium storage, however, their capacity fades quickly owing to substantial interlayer expansion/shrinkage (i.e., up 60%) induced structural degradation. Here, Ti 3 C 2 T x MXene nanosheets are used as a fast electron/potassium‐ion dual‐function conductor construct the framework of all‐integrated graphite nanoflake (GNF)/MXene (GNFM) electrodes. The continuous constructs 3D channel transfer and endows GNFM electrodes with high stability. Owing this unique framework, exhibit much enhanced storage performances than that conventional polymer‐bonded even at mass loadings. Moreover, also impressive cyclability in non‐flammable electrolytes further assemble novel potassium‐ion capacitors an excellent energy/power densities (113.1 Wh kg –1 12.2 kW ). New insights into phase transition mechanism verified by operando XRD. Density functional theory calculations demonstrate can promote electron diffusion heterointerface between GNF MXene. Therefore, results designed multifunctional frameworks provide new paradigm producing efficient anodes.

Language: Английский

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Assembly of Nanofluidic MXene Fibers with Enhanced Ionic Transport and Capacitive Charge Storage by Flake Orientation

ACS Nano, Journal Year: 2021, Volume and Issue: 15(4), P. 7821 - 7832

Published: April 9, 2021

MXenes are an emerging class of highly conductive two-dimensional (2D) materials with electrochemical storage features. Oriented macroscopic Ti3C2Tx fibers can be fabricated from a colloidal 2D nematic phase dispersion. The layered ideal candidates for constructing high-speed ionic transport channels to enhance the capacitive charge performance. In this work, we assemble high degree flake orientation by wet spinning process controlled speeds and morphology spinneret. addition effects cross-linking magnesium ions between flakes, electronic conductivity mechanical strength as-prepared have been improved 7200 S cm–1 118 MPa, respectively. oriented present volumetric capability up 1360 F cm–3 even in Mg-ion based neutral electrolyte, contributions both nanofluidic ion intercalation pseudocapacitance. driven great endows MXene attributes serving as cables active fiber-type energy storage, biosensors, potentially biocompatible fibrillar tissues.

Language: Английский

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