Preparation of a Reduced Graphene Oxide Wrapped Lithium-Rich Cathode Material by Self-Assembly

Facile synthesis of a novel BaSnO3/MXene nanocomposite by electrostatic self-assembly for efficient photodegradation of 4-nitrophenol

Photocatalysis is regarded as one of the most effective strategies for the removal of the toxic organic pollutants from aqueous solutions. However, a lack of the efficient photocatalysts prevents the widespread practical application. Herein, the electrostatic self-assembly method has been designed for facile synthesis of a novel BaSnO₃/PDDA/MXene (BSO/P/MX) nanocomposite as high efficient photocatalyst. In this nanocomposite, the BaSnO₃ (BSO), poly (dimethyl-diallylammonium chloride) (PDDA) and MXene (Ti₃C₂T_x) act as the active species, structure stabilizer and efficient electron transfer medium, respectively. Due to the strong synergy of the nanocomposite, the electron-transferring ability as well as the charge separation efficiency is boosted and thus high catalytic activity achieves towards the photodegradation of 4-nitrophenol. The superior degradation rate of 98.8% and a rate constant K of 0.09113 min^-1 have been realized within 75 min of ultraviolet (UV) light irradiation over the BSO/P/MX-8% catalyst. This as-prepared nanocomposite with the excellent catalytic activity can be employed as a promising photocatalyst for treating the organic pollutants from aqueous solutions.

High Lithium Ion Transport Through rGO-Wrapped LiNi0.6Co0.2Mn0.2O2 Cathode Material for High-Rate Capable Lithium Ion Batteries

In this work, we show an effective ultrasonication-assisted self-assembly method under surfactant solution for a high-rate capable rGO-wrapped LiNi_0.6Co_0.2Mn_0.2O₂ (Ni-rich cathode material) composite. Ultrasonication indicates the pulverization of the aggregated bulk material into primary nanoparticles, which is effectively beneficial for synthesizing a homogeneous wrapped composite with rGO. The cathode composite demonstrates a high initial capacity of 196.5 mAh/g and a stable capacity retention of 83% after 100 cycles at a current density of 20 mA/g. The high-rate capability shows 195 and 140 mAh/g at a current density of 50 and 500 mA/g, respectively. The high-rate capable performance is attributed to the rapid lithium ion diffusivity, which is confirmed by calculating the transformation kinetics of the lithium ion by galvanostatic intermittent titration technique (GITT) measurement. The lithium ion diffusion rate (D _Li) of the rGO-wrapped LiNi_0.6Co_0.2Mn_0.2O₂ composite is ca. 20 times higher than that of lithium metal plating on anode during the charge procedure, and this is demonstrated by the high interconnection of LiNi_0.6Co_0.2Mn_0.2O₂ and conductive rGO sheets in the composite. The unique transformation kinetics of the cathode composite presented in this study is an unprecedented verification example of a high-rate capable Ni-rich cathode material wrapped by highly conductive rGO sheets.

Advances in nanostructures fabricated via spray pyrolysis and their applications in energy storage and conversion

This review provides insight into various nanostructures designed by spray pyrolysis and their applications in energy storage and conversion.

A cationic azobenzene-surfactant-modified graphene hybrid: unique photoresponse and electrochemical behavior

Surfactant-modified graphene hybrids containing azobenzene groups were for the first time prepared, and the electrochemical performance was investigated. The hybrids were obtained by electrostatic interactions between cationic azobenzene-surfactants and negatively charged graphene oxide in water. The electrostatic interactions, chemical structure and photoresponse of the hybrids were measured by using zeta potential values, fluorescence spectra, FTIR, XPS, XRD, SEM, UV-Vis absorption, AFM and Raman spectra. The electrochemical performance was estimated using cyclic voltammetry. The results show that strong electrostatic interactions exist between the azobenzene surfactants and graphene oxide. Notably, this azobenzene-graphene hybrid can self-assemble into aggregation structures in aqueous solution. Besides, the self-assembly can be reversibly controlled by ultraviolet light (365 nm) and blue light (455 nm) irradiation. This process is driven by the photoinduced polarity change of the cationic azobenzene surfactant and is responsible for the graphene hybrids' electrochemical performance. It is the first example of the reversible self-assembly of graphene driven by light irradiation.

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.