Green and scalable electrochemical routes for cost‐effective mass production of MXenes for supercapacitor electrodes

Abstract

One of the most unique properties of two‐dimensional carbides and nitrides of transition metals (MXenes) is their excellent water dispersibility and yet possessing superior electrical conductivity but their industrial‐scale application is limited by their costly chemical synthesis methods. In this work, the niche feature of MXenes was capitalized in the packed‐bed electrochemical reactor to produce MXenes at an unprecedented reaction rate and yield with minimal chemical waste. A simple NH4F solution was employed as the green electrolyte, which could be used repeatedly without any loss in its efficacy. Surprisingly, both fluoride and ammonium were found to play critical roles in the electrochemical etching, functionalization, and expansion of the layered parent materials (MAXs) through which the liberation of ammonia gas was observed. The electrochemically produced MXenes with excellent conductivity, applied as supercapacitor electrodes, could deliver an ultrahigh volumetric capacity (1408 F cm−3) and a volumetric energy density (75.8 Wh L−1). This revolutionary green, energy‐efficient, and scalable electrochemical route will not only pave the way for industrial‐scale production of MXenes but also open up a myriad of versatile electrochemical modifications for improved functional MXenes.

Efficient Synergism of Chemisorption and Wackenroder Reaction via Heterostructured La2O3‐Ti3C2Tx ‐Embedded Carbon Nanofiber for High‐Energy Lithium‐Sulfur Pouch Cells

“…First, the 2D Ti 3 C 2 T x MXene nanosheets are prepared by electrochemical etching of the MAX phase (Figure S1, Supporting Information) following the same procedure as reported in our previous work. [ 33 ] Afterward, the MXene nanosheets are mixed with polyacrylonitrile (PAN) and lanthanum salt in N, N ‐Dimethylformamide (DMF) solvent, and form nanofibers after an electrospinning process under 14 kV high voltage. As shown in Figure 1b and Figure S2, Supporting Information, the MXene nanosheets can be observed in La 2 O 3 ‐MXene@PAN nanofibers (Figure 1b) and MXene@PAN fibers (Figure S2a, Supporting Information) when compared with the La 2 O 3 @PAN fibers (Figure S2b, Supporting Information).…”

“…In addition, the progress in green and cost-effective technology will facilitate the scalability of MXene materials for practical application in Li-S batteries. [33] At present, the research only focuses on the excellent conductivity and large specific surface area of MXene. [34][35][36][37][38][39] The catalytic mechanism of MXene in composite materials is still debated and needs to be further explored.…”

Insights on advanced g‐C3N4 in energy storage: Applications, challenges, and future

“…Supercapacitors have the advantages of high power density and fast discharge speed, and are widely used for energy storage. [258][259][260][261][262] At present, most pseudocapacitive materials (such as nickel hydroxide) in supercapacitors have poor cycling stability and small specific surface areas. [263][264][265] g-C 3 N 4 , as a special nitrogen-doped carbon material, has rich nitrogen content and can enhance surface polarity and improve surface wettability.…”

“…Supercapacitors have the advantages of high power density and fast discharge speed, and are widely used for energy storage 258–262 . At present, most pseudocapacitive materials (such as nickel hydroxide) in supercapacitors have poor cycling stability and small specific surface areas 263–265 .…”

Etching Strategy for Photocatalysis: The Evolution of Structures and Properties

“…Therefore, etching methods are able to improve the activity of photocatalysts by the introduce of various vacancies, the exposure of high active facets, and the fabrication of nanostructures with high specific surface. [31][32][33][34] At present, there is no reviewer about the etching modification and synthesis photocatalysts.…”