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Research Article Issue
Moiré-superlattice MXenes enabled ultra-stable K-ion storage in neutral electrolyte
Nano Research 2023, 16 (4): 5006-5017
Published: 21 January 2023
Downloads:80

Ti3C2 MXene is an auspicious energy storage material due to its metallic conductivity and layered assembly. However, in the real working condition of electrochemical energy storage with long cycle charging–discharging, a structural collapse is usually caused by the stacking of its layers creating a large attenuation of specific capacitance. Inspired by the superlattice effect of magic angle graphene, we conducted microscopical regulation of rotation mismatch on the Ti3C2 lattice; consequently, a hexagonal few-layered Ti3C2 free-standing film constructed with Moiré-superlattices. Such finding not only solves the problem of Ti3C2 structural collapse but also dramatically improves the specific capacitance of Ti3C2 as a supercapacitor electrode under long cycle charging and discharging. The ultra-stable energy storage of this electrode material in a neutral aqueous electrolyte was realized. Moreover, the formation mechanism of rotating Moiré pattern is revealed through microscopy and microanalysis of the produced Moiré pattern, assisted with modeling and analyzing the underlying mechanism between the Moiré pattern and the rotation angle. Our work provides experimental and theoretical support for future construction of Moiré-superlattice structure for a wide range of MXene phases and is undoubtedly promoting the development of MXene materials in the field of energy storage.

Research Article Issue
Individually-atomic governing d–π* orbital interactions via Cu-promoted optimization of Fe-d band centers for high-efficiency zinc-air battery
Nano Research 2023, 16 (4): 4634-4642
Published: 05 November 2022
Downloads:88

It is challenging for precise governing of electronic configuration of the individually-atomic catalysts toward optimal electrocatalysis, as d-band configuration of a metal center determines the adsorption behavior of reactive species to the center in oxygen reduction reaction (ORR). The addition of Cu atom modifies the d-band center position of Fe central atom, thus strengthening the d–π* orbital interactions. Herein, FeCu-NC catalyst in the nitrogen-doped carbon (NC) support containing individual dual-metal CuN4/FeN4 sites was prepared by the surface confinement strategy of zeolitic imidazolate framework (ZIF), treated as a model catalyst. Experimentally and theoretically co-verified dual-metal CuN4/FeN4 sites highly dispersed in the NC support, enable transferring more electrons from FeN4 sites to *OH intermediates, thereby accelerating the desorption process of *OH species. Superior to those commercial Pt/C, Our FeCu-NC catalyst exhibited extraordinary ORR activity (with a E1/2 as high as 0.87 V) and cycling stability in 0.1 M KOH electrolyte, and thereof demonstrated excellent discharge performance in zinc-air batteries. Our construction of dual-atom catalysts (DACs) provides a strategy for atom-by-atom designing high-efficiency catalysts via orbital regulation.

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