Reprocessable squeezing electrode fabrication of olive-like Fe/Co/O nanoparticle@three dimensional nitrogen-doped reduced graphene oxides for high performance lithium batteries

A Universal Strategy for Constructing Seamless Graphdiyne on Metal Oxides to Stabilize the Electrochemical Structure and Interface

The structural and interfacial stabilities of metal oxides (MOs) are key issues while facing the volumetric variation and intensive interfacial polarization in electrochemical applications, including lithium-ion batteries (LIBs), supercapacitors, and catalysts. The growth of a seamless all-carbon interfacial layer on MOs with complex dimensions is not only a scientific problem, but also a practical challenge in these fields. Here, the growth of graphdiyne under ultramild condition is successfully implemented in situ for coating MOs of complex dimensions. The seamless all-carbon interface and conductive network are formed at the same time. This method cleverly avoids the structural degradation of MOs at a high temperature in the presence of traditional carbon materials. Under the protection of the high-quality graphdiyne layer, the samples as LIB anodes deliver high performances in terms of Coulomb efficiency, capacity, long-term retention, and structural and interfacial stabilities. Both experimental achievements and theoretical calculations demonstrate that the graphdiyne is a particular protection layer for MOs and plays a crucial role for preventing the structural and interfacial degradation of the electrode. Furthermore, the universality of this method will promote the potential applications of many promising MOs in other electrochemical fields.

Facile Synthesis of Highly Dispersed Co3O4 Nanoparticles on Expanded, Thin Black Phosphorus for a ppb-Level NO x Gas Sensor

Expanded few-layer black phosphorus nanosheets (FL-BP NSs) were functionalized by branched polyethylenimine (PEI) using a simple noncovalent assembly to form air-stable overlayers (BP-PEI), and a Co₃O₄@BP-PEI composite was designed and synthesized using a hydrothermal method. The size of the highly dispersed Co₃O₄ nanoparticles (NPs) on the FL-BP NSs can be controlled. The BP-C5 (190 °C for 5 h) sensor, with 4-6 nm Co₃O₄ NPs on the FL-BP NSs, exhibited an ultrahigh sensitivity of 8.38 and a fast response of 0.67 s to 100 ppm of NO _x at room temperature in air, which is 4 times faster than the response of the FL-BP NS sensor, and the lower detection limit reached 10 ppb. This study points to a promising method for tuning properties of BP-based composites by forming air-stable overlayers and highly dispersed metal oxide NPs for use in high-performance gas sensors.

Grape-Like Fe3O4 Agglomerates Grown on Graphene Nanosheets for Ultrafast and Stable Lithium Storage

An in situ simple and effective synthesis method is effectively exploited to construct MOF-derived grape-like architecture anchoring on nitrogen-doped graphene, in which ultrafine Fe3O4 nanoparticles are uniformly dispersed (Fe3O4@C/NG). In this hybrid hierarchical structure, new synergistic features are accessed. The graphene oxide plane with functional groups is expected to alleviate the aggregation problem in the MOFs' growth. Moreover, the morphology and size of iron-based MOFs and carbon content are conveniently controlled by controlling the solution concentration of precursor. Through making use of in situ carbonization of the organic ligands in MOFs, Fe3O4 subunits are effectively protected by 3D interconnected conductive carbon at microscale. Consequently, when applied as anode materials, even as high as 10 A g(-1) after 1000 cycles, Fe3O4@C/NG still maintains as high as 458 mA h g(-1).

Organic solvent-assisted free-standing Li2MnO3·LiNi1/3Co1/3Mn1/3O2 on 3D graphene as a high energy density cathode

A novel organic solvent-assisted freeze-drying pathway, which can effectively protect and uniformly distribute active particles, is developed to fabricate a free-standing Li₂MnO₃·LiNi_1/3Co_1/3Mn_1/3O₂ (LR)/rGO electrode on a large scale.