Senyang Song,Xiaoyan Ma,Wenyue Li,Boyuan Zhang,Bo Shao,Xiaoyu Chang,Xiaoju Liu
With the development of power supplies for wearable devices , electrode materials with dual functions have received extensive attention. Herein, we report a strategy of preparing stylophora coral-like Ni/Co bimetal metal organic framework (MOF) with furan-based derivatives as ligands through the simple solvothermal method, which can be utilized as a dual-function electrode material to build supercapacitors and non-enzymatic glucose sensing. It can be found that the high molecular stacking properties of the rigid furan ring skeleton combined with the unique stylophora coral-like morphology can greatly improve the charge transfer efficiency of the electrode reaction process, and the structure of the bimetallic node can effectively adjust the three-dimensional electronic structure, making high capacitive performance during charge storage. The specific capacitance of the furan-based bimetallic MOF material is as high as 531 C g −1 at a current density of 1 A g −1 with a high capacitance retention rate of 83.4% after 5000 cycles. In addition, the glucose sensing performance is analyzed and an outstanding sensitivity value of 366 µA mM −1 cm −2 is achieved with a low limit of detection (2 μM). The as-synthesized furan-based bimetallic MOF material is a promising candidate for electrochemical supercapacitors and efficient glucose detection.
Chengjun Gu,Zhihao Liu,Xiang Gao,Qi Zhang,Zhanhui Zhang,Zhitian Liu,Chengliang Wang
Organic molecules and polymers have been widely used in aqueous sodium-ion capacitors. However, the difference in the reaction kinetics of the electroactive polymer and its monomer has been overlooked. In this study, a comparative study of the sodium-ion storage performance and the reaction kinetics is performed. The poly(perylene diimides) which is named EDP exhibits decreased crystallinity, smaller particle size with a rough surface, higher specific capacitance, lower reduction potential, better cycling stability, and rate performance, compared with its monomer 3,4,9,10-perylenetetracarboxylic dianhydride. The reaction kinetics study proves that the EDP shows faster sodium-ion diffusion and more capacitive charge storage, which are responsible for the high-rate capability.
The ammonization treatment is applied to a prototype ordered double-transition metal MXene known as Mo2TiC2Tx at different annealing temperatures (400, 500 and 600 °C) and durations (1 h and 2 h). The lattice structures, micro-morphologies, and chemical compositions of the resulting ammoniated MXenes are characterized by XRD, SEM, TEM, XPS and EPMA. All ammoniated MXenes preserve the layered microstructure of the parent carbide 2D material, and N atoms are successfully doped into the lattice sites to form carbonitride MXenes, denoted as Mo2Ti(C1−δNδ)2Tx. The Hall measurements are carried out to evaluate the electrical conductivity of ammoniated MXenes and raw Mo2TiC2Tx, and the results indicate that the carbonitride forms exhibit higher electrical conductivities and electron concentrations than the raw 2D material. The electrochemical properties of ammoniated MXenes are investigated by means of charge–discharge cycling CV tests, the GITT and EIS measurements at various scan rates. The ammoniated MXene sample (N400-1h) could deliver a storage capacity of 750 mA h g−1 (200 mA h g−1) at a current density of 0.03 A g−1 (2 A g−1). It is found that the capacitive charge storage mechanism through the intercalation reaction process dominates the total capacity for the ammoniated MXenes. The diffusion dynamics of Li+ in all investigated MXene electrodes show a two-stage lithiation mechanism in which the apparent diffusion coefficient is regulated by the different numbers of vacancies in the absorbate layers at various lithiation stages in the GITT curves. Overall, ammoniated MXenes also show superior performances in Li+ diffusion dynamics and charge transfer kinetics at the electrode–electrolyte interface to those of raw Mo2TiC2Tx, elucidating a new avenue for the use of ammoniated double-transition metal o-MXenes as high-performance electrode materials for LIBs and supercapacitors in the future.
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