In this study, we propose a versatile method for synthesizing uniform three-dimensional (3D) metal carbides, nitrides, and carbonitrides (MXenes)/metal–organic frameworks (MOFs) composites (Ti3C2TX/Cu-BTC, Ti3C2TX/Fe,Co-PBA, Ti3C2TX/ZIF-8, and Ti3C2TX/ZIF-67) that combine the advantages of MOFs and MXenes to enhance stability and improve conductivity. Subsequently, 3D hollow Ti3C2TX/ZIF-67/CoV2O6 composites with excellent electron- and ion-transport properties derived from Ti3C2TX/ZIF-67 were synthesized. The specific capacitance of the Ti3C2TX/ZIF-67/CoV2O6 electrode was 285.5 F g−1, which is much higher than that of the ZIF-67 and Ti3C2TX/ZIF-67 electrode. This study opens a new avenue for the design and synthesis of MXene/MOF composites and complex hollow structures with tailorable structures and compositions for various applications. 

In Situ Growth of Three‐Dimensional MXene/Metal‐Organic Framework Composites for High‐Performance Supercapacitors

In this study, we propose a versatile method for synthesizing uniform three-dimensional (3D) metal carbides, nitrides, and carbonitrides (MXenes)/metal-organic frameworks (MOFs) composites (Ti3 C2 TX /Cu-BTC, Ti3 C2 TX /Fe,Co-PBA, Ti3 C2 TX /ZIF-8, and Ti3 C2 TX /ZIF-67) that combine the advantages of MOFs and MXenes to enhance stability and improve conductivity. Subsequently, 3D hollow Ti3 C2 TX /ZIF-67/CoV2 O6 composites with excellent electron- and ion-transport properties derived from Ti3 C2 TX /ZIF-67 were synthesized. The specific capacitance of the Ti3 C2 TX /ZIF-67/CoV2 O6 electrode was 285.5 F g-1 , which is much higher than that of the ZIF-67 and Ti3 C2 TX /ZIF-67 electrode. This study opens a new avenue for the design and synthesis of MXene/MOF composites and complex hollow structures with tailorable structures and compositions for various applications. 

In Situ Growth of Three‐Dimensional MXene/Metal–Organic Framework Composites for High‐Performance Supercapacitors

Limited by single metal active sites and low electrical conductivity, designing nickel‐based metal–organic framework (MOF) materials with high capacity and high energy density remains a challenge. Herein, a series of bi/multimetallic MOF‐74 family materials in situ grown on carbon cloth (CC) by doping Mx+ ions in Ni‐MOF‐74 is fabricated: NiM‐MOF@CC (M = Mn2+, Co2+, Cu2+, Zn2+, Al3+, Fe3+), and NiCoM‐MOF@CC (M = Mn2+, Zn2+, Al3+, Fe3+). The type and ratio of doping metal ions can be adjusted while the original topology is preserved. Different metal ions are confirmed by X‐ray absorption fine structure (XAFS). Furthermore, these Ni‐based MOF electrodes are directly utilized as cathodes for aqueous nickel–zinc batteries (NZBs). Among all the as‐prepared electrodes, NiCo‐MOF@CC‐3 (NCM@CC‐3), with an optimized Co/Ni ratio of 1:1, exhibits the best electrical conductivity, which is according to the density functional theory (DFT) theoretical calculations. The NCM@CC‐3//Zn@CC battery achieves a high specific capacity of 1.77 mAh cm–2, a high areal energy density of 2.97 mWh cm–2, and high cycling stability of 83% capacity retention rate after 6000 cycles. The synthetic strategy based on the coordination effect of metal ions and the concept of binder‐free electrodes provide a new direction for the synthesis of high‐performance materials in the energy‐storage field.

In Situ Synthesis of MOF‐74 Family for High Areal Energy Density of Aqueous Nickel–Zinc Batteries

Metal-organic framework (MOF) composites as promising materials for energy storage applications.

Ambient electroreduction of nitrogen (N2) is considered as a green and feasible approach for ammonia (NH3) synthesis, which urgently demands for efficient electrocatalyst. Morphology has close relationship with catalytic activity of heterogeneous catalysts. Nanoribbon is attractive nanostructure, which possesses the flexibility of one-dimensional nanomaterials, the large surface area of two-dimensional nanomaterials, and lateral size confinement effects. In this work, Cu3P nanoribbon is proposed as a highly efficient electrocatalyst for N2-to-NH3 conversion under benign conditions. When measured in N2-saturated 0.1 M HCl, such Cu3P nanoribbon achieves high performance with an excellent Faradaic efficiency as high as 37.8% and a large yield of 18.9 µg·h−1µmgcat.−1 at −0.2 V. It also demonstrates outstanding stability in long-term electrolysis test at least for 45 h. 

https://link.springer.com/content/pdf/10.1007/s12274-022-4568-z.pdf

Enhanced N2-to-NH3 conversion efficiency on Cu3P nanoribbon electrocatalyst

MXenes have attracted great interests as supercapacitors due to their metallic conductivity, high density, and hydrophilic nature. Herein we report Ti3 C2 -Cu/Co hybrids via molten salt etching in which the existence of metal atoms and their interactions with MXene via surficial O atoms were elucidated by XAFS for the first time. The electrochemical investigation of Ti3 C2 -Cu electrode demonstrated the pseudocapacitive contribution of Cu and a splendid specific capacitance of 885.0 F g-1 at 0.5 A g-1 in 1.0 M H2 SO4 . Symmetric supercapacitor Ti3 C2 -Cu//Ti3 C2 -Cu was demonstrated with operating voltage of 1.6 V, areal capacitance of 290.5 mF cm-2 at 1 mA cm-2 , and stability over 10 000 cycles. It delivered an areal energy density of 103.3 μWh cm-2 at power density of 0.8 mW cm-2 , based on which a supercapacitor pouch was fabricated. It provides deeper insights into the molten salt mechanism and strategies for designing MXene-based materials for electrochemical energy storage.

Ye-Can Pi

Papers

MXene-Copper/Cobalt Hybrids via Lewis Acidic Molten Salts Etching for High Performance Symmetric Supercapacitors.

MXenes nanocomposites for energy storage and conversion