A new MXene/Ag composite was synthesized by direct reduction of a AgNO3 aqueous solution in the presence of MXene (Ti3C2(OH)0.8F1.2). The as-received MXene/Ag composite can be deemed as an excellent anode material for lithium-ion batteries, exhibiting an extraordinary long cycle lifetime with a large capacity at high charge-discharge rates. The results show that Ag self-reduction in MXene solution is related to the existence of low-valence Ti. Reversible capacities of 310 mAh·g(-1) at 1 C (theoretical value being ∼320 mAh·g(-1)), 260 mAh·g(-1) at 10 C, and 150 mAh·g(-1) at 50 C were achieved. Remarkably, the composite withstands more than 5000 cycles without capacity decay at 1-50 C. The main reasons for the long cycle life with high capacity are relevant to the reduced interface resistance and the occurrence of Ti(II) to Ti(III) during the cycle process.

Covalent organic frameworks (COFs) are potentially promising electrode materials for electrochemical charge storage applications thanks to their pre‐designable reticular chemistry with atomic precision, allowing precise control of pore size, redox‐active functional moieties, and stable covalent frameworks. However, studies on the mechanistic and practical aspects of their zinc‐ion storage behavior are still limited. In this study, a strategy to enhance the electrochemical performance of COF cathodes in zinc‐ion batteries (ZIBs) by introducing the quinone group into 1,4,5,8,9,12‐hexaazatriphenylene‐based COFs is reported. Electrochemical characterization demonstrates that the introduction of the quinone groups in the COF significantly pushes up the Zn2+ storage capability against H+ and elevates the average (dis‐)charge potential in aqueous ZIBs. Computational and experimental analysis further reveals the favorable redox‐active sites that host Zn2+/H+ in COF electrodes and the root cause for the enhanced electrochemical performance. This work demonstrates that molecular engineering of the COF structure is an effective approach to achieve practical charge storage performance.

Rationally tailored intercalation for two-dimensional (2D) layered MXene materials has aroused extraordinary enthusiasm for broadening their applications. Herein, a novel sandwiched structural 2D MXene-iron oxide (MXI) material, prepared by selectively exfoliating an Al layer followed by magnetic ferric oxide intercalation, exhibits remarkable applicability to trace phosphate sequestration in the environmental remediation realm. Compared with commercial adsorbents, the resultant MXI nanocomposite exhibits a fast separation in 120 s together with the superior treatment capacities of 2100 kg and 2400 kg per kg in simulated and real phosphate wastewater applications, respectively. Such efficient sequestration is ascribed to the formation of a unique nano-ferric oxide morphology. The ultrafine nano-Fe2O3 particles can intercalate into the interior layers of MXene, widening the layer distance, and stimulating the available overlapping activated layers; while the efficient phosphate removal can be achieved by the strong complexation onto the embedded magnetic nano-Fe3O4 with a unique sandwich-structure as well as the stimulated Ti-O terminal within MXene. Apart from the fact that this approach suggests a complementary means for environmental remediation, it opens a new trajectory to achieve the functionalization of MXene.

Differing from graphene, the activated groups on the surface of layered two-dimensional titanium carbide (MXene) materials bestow superiority to self-assemble some novel MXene derivatives with intriguing chemical/physical properties. Here we first report a series of new MXene-Ag composites by directly mixing AgNO3 and alkalization-intercalated MXene (alk-MXene, Ti3C2(OH/ONa)2) solution containing polyvinylpyrrolidone (PVP) at room temperature, in which an analogous urchin-shaped MXene-Ag0.9Ti0.1 bimetallic nanowire composite exhibits unexpected electrocatalytic activity for the oxygen reduction reaction. The addition of PVP solution induces the formation of 5-fold nanotwin Ag seeds, which then grow into Ag/Ti (Ag0.9Ti0.1) bimetallic nanowires. The unique bimetallic nanowires favor a four-electron transfer process, and exhibit high current density and good stability by offering numerous oxygen adsorption sites and shortening the diffusion path of adsorbed oxygen. The results represent a new step for the electrocatalytic applications of MXene materials, and also motivate enthusiasm in the quest for new MXene derivations.

An antimony-based photoluminescent ionic liquid, namely [Bmim]2SbCl5, has been synthesized and characterized. It exhibits bright yellow and white light emission, with quantum yield as high as 86.3% under UV irradiation.