The magnesium (Mg) metal anodes of magnesium batteries have attracted significant attention because of their high theoretical capacity, high safety, and low cost. Their development is hindered by the passivation characteristics of magnesium, especially the serious voltage lag and corrosion polarization in aqueous solutions. This study demonstrates a novel approach involving the electrophoresis deposition on the surface of a magnesium electrode with MXene@ZIF-67. MXene@ZIF-67 is a heterojunction material with a core-shell structure obtained from MXene and ZIF-67 by the in-situ growth method. The addition of ZIF-67 not only solves the problem of MXene layer-to-layer instability, but also improves the corrosion resistance of magnesium metal by utilizing the properties of ZIF-67 material topology. The core-shell structure design of the modified film layer enables MXene and ZIF-67 to achieve efficient synergy. On the one hand, the unique lamellar structure of MXene is utilized to achieve uniform Mg 2 + flux and reduce the interfacial resistance of the magnesium anode, and on the other hand, the unique ionic conductor performance of ZIF-67 enables precise separation of solvent molecules and simultaneous selective Mg 2+ transport. So, the film is beneficial for interfacial stability and reaction kinetics. The modified Mg battery exhibits a reduction in voltage lag time from 7.2 seconds to 1.3 seconds. A notable reduction in polarity and enhanced stability in plating and stripping was observed in magnesium metal battery for 300 cycles. The DFT calculations show that there is a high adsorption energy between the MXene@ZIF-67 film and the magnesium alloy.
Mei Wan,Congling Shi,Lei Chen,Lei Deng,Yueping Qin,Honglei Che,Jingyun Jing,Junyi Li,Xiaodong Qian
Ammonium polyphosphate (APP) is the most commercially valuable phosphorus-based flame retardant, but poor interaction with the polymer interface limits the flame-retardant efficiency. In this work, a new type of multi-layered nanomaterial coating APP (APP-PEI@MXene@ZIF-67) was prepared and introduced into thermoplastic polyurethane (TPU) polymers by a simple and green assembly strategy. The effects of different loading shells of modified APP on the flame retardancy of TPU composites were investigated, as well as their gas/condensed phase thermal degradation products and their flame-retardant mechanisms. The results showed that APP-PEI@MXene@ZIF-67 was more favorable for catalytic char formation than APP, and the residual char formed by its composites was denser and more continuous. Compared with the pure TPU, the pHRR, THR, pSPR, and TSP of TPU/APP-PEI@MXene@ZIF-67–2BL composites were decreased by 72.75 %, 87.25 %, 59.58 %, and 85.97 %, respectively, which significantly reduced the heat and smoke release during the combustion process. The gas-phase and condensed-phase flame retardant mechanisms synergized to construct a possible approach to address the fire risk and heat/smoke hazards of TPUs and promote the extensive application of TPU polymers.
Luteolin (LUT) is one of the biologically active functional components, which was widely used in pharmacological applications. Thus, development of sensitive analytical methods for LUT determination is highly desired. In this work, Ti 3 C 2 -MXene/ZIF-67/CNTs heterostructure was exploited as a new electrochemical sensing platform for the sensitive determination of LUT. For the design of composite, the in-situ growth of ZIF-67 on CNTs surface ensures the stability of their binding and enhances the synergetic catalysis. Conductive MXene as matrix for the loading of ZIF-67/CNTs can promote the catalytic ability of composite. Electrochemical results show that the MXene/ZIF-67/CNTs modified electrode displays preeminent electrocatalytic activity and enhances electrochemical response to the redox reaction of LUT, ascribing to the synergistic effect of ZIF-67/CNTs and MXene. Upon the optimization of experimental parameters, e.g., pH, enrichment time, the sensor based on MXene/ZIF-67/CNTs composite exhibits excellent performance with wide linear relationship ranging from 0.1–1000 nM and a low limit of detection (LOD) of 0.03 nM (S/N = 3). Besides, MXene/ZIF-67/CNTs electrode performs high selectivity, stability, and acceptable reproducibility. Furthermore, the constructed sensor was successfully utilized to detect LUT in real samples with satisfactory recovery.
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