High Capacity and Rate Capability Binder‐less Ternary Transition Metal‐organic Framework as Anode Material for Lithium‐ion Battery

Construction of Well-Defined Two-Dimensional Architectures of Trimetallic Metal-Organic Frameworks for High-Performance Symmetric Supercapacitors

The high surface-to-volume ratio and extraordinarily large-surface area of two-dimensional (2D) metal-organic framework (MOF) architectures have drawn particular interest for use in supercapacitors. To achieve an excellent electrode material for supercapacitors, well-defined 2D nanostructures of novel trimetallic MOFs were developed for supercapacitor applications. Multivariate MOFs (terephthalate and trimesate MOF) with distinctive nanobrick and nanoplate-like structures were successfully synthesized using a straightforward one-step reflux condensation method by combining Ni, Co, and Zn metal species in equimolar ratios with two different ligands. Furthermore, the effects of the tricarboxylic and dicarboxylic ligands on cyclic voltammetry, charge-discharge cycling, and electrochemical impedance spectroscopy were studied. The derived terephthalate and trimesate MOFs are supported with stainless-steel mesh and provide a suitable electrolyte environment for rapid faradaic reactions with an elevated specific capacity, excellent rate capability, and exceptional cycling stability. It shows a specific capacitance of 582.8 F g-1, a good energy density of 40.47 W h kg-1, and a power density of 687.5 W kg-1 at 5 mA cm-2 with an excellent cyclic stability of 92.44% for 3000 charge-discharge cycles. A symmetric BDC-MOF//BDC-MOF supercapacitor device shows a specific capacitance of 95.22 F g-1 with low capacitance decay, high energy, and power densities which is used for electronic applications. These brand-new trimetallic MOFs display outstanding electrochemical performance and provide a novel strategy for systematically developing high-efficiency energy storage systems.

High sensitivity electrochemical detection of ultra-trace imidacloprid in fruits and vegetables using a Fe-rich FeCoNi-MOF

High sensitivity and ultra-trace detection of imidacloprid are important and challenging in the field of food. In this study, we prepared a Fe-rich FeCoNi-MOF in-situ modified nickel foam working electrode by one-step hydrothermal method, and achieved a highly sensitive detection of the imidacloprid. The characterization techniques confirmed that Fe-rich FeCoNi-MOF had excellent crystallinity, tighter structure, and exposed rich active sites. The detection results showed that Fe-rich FeCoNi-MOF electrochemical sensor had a minimum detection limit of 0.04 pmol/L (100 times lower than that of the bioelectrochemical sensors), a wide response range (1 pmol/L-120 μmol/L), and high sensitivity (124 μA pmol/L^-1 cm^-2). These advantages of the electrochemical sensor were revealed theoretically by the valence change of active metal and the first principle calculation. Lastly, the Fe-rich FeCoNi-MOF electrochemical sensor was applied to detect imidacloprid in apple, fresh tea leaves, tomato, cucumber, and had an excellent recovery of 98-102.8 %.