Novel strategy for the preparation of graphene-encapsulated mesoporous metal oxides with enhanced lithium storage

A facile solvothermal syntheses of NiFe layered double hydroxide-Bi2MoO6 heterostructure/reduced graphene oxide with efficient photodegradation for tetracycline

A heterojunction of NiFe layered double hydroxide (NiFe LDH)-Bi₂MoO₆ (BMO) loaded on reduced graphene oxide (RGO) sheets was synthesized via an eco-friendly solvothermal reaction. The structural characterization shows that NiFe LDH-BMO heterojunctions are well-distributed on the surface of silk-like transparent RGO sheets. The modification of BMO by NiFe LDH and RGO greatly enhances the photocatalytic performance of BMO for degradation of tetracycline (TC) under visible light. The photocatalyst prepared with 3 wt% RGO shows the highest activity and cycle stability. TC can be completely removed in 80 min, which is about 8.7 times that pure BMO, and showing excellent reusability even after five cycles. The excellent enhancement of photocatalytic performance of NiFe LDH-BMO/RGO composite is attributed to the unique sheet-on-sheet hierarchical heterostructure combined with RGO sheets, facilitating the visible light absorption and photogenerated charge carriers separation.

Rational design of 3D net-like carbon based Mn3O4 anode materials with enhanced lithium storage performance

A three-dimensional net-like Mn3O4/carbon paper composite was realized, which delivers a remarkably enhanced rate performance and excellent cycling stability for lithium-ion storage.

Polypyrrole functionalized Cobalt oxide Graphene (COPYGO) nanocomposite for the efficient removal of dyes and heavy metal pollutants from aqueous effluents

A cobalt oxide graphene nanocomposite functionalized with polypyrrole (COPYGO) having a heterogenous porous structure was synthesized using hydrothermal method. Microscopic imaging of the COPYGO surface revealed its highly porous and ordered features. The adsorption performance of the COPYGO composite was systemically investigated for Methylene Blue (MB), Congo red (CR) dyes and toxic lead (Pb(II)) and Cadmium (Cd(II)) metals. These were selected as they are the common pollutants in industrial wastewater. The COPYGO was found to be thermally stable up to 195 ^oC with a specific surface area of 133 m² g^-1. Experimental data indicates that the COPYGO follows Langmuir and Temkin adsorption isotherm. The COPYGO was efficient in removing MB (92.8%), CR (92.2%), Pb(II) (93.08%) and Cd(II) (95.28%) pollutants at pH 7.2, 5.0, 5.5 and 6.1 respectively from the simulated effluents. The maximum adsorption capacity (Q_max) observed for MB 663.018 mg g^-1, CR 659.056 mg g^-1, Pb(II) 780.363 mg g^-1 and Cd(II) 794.188 mg g^-1 pollutants. The thermodynamic analysis of the COPYGO indicates that the adsorption is endothermic and spontaneous in nature. COPYGO showed very high efficient removal rate for the pollutants in simulated effluents which guaranteed its benefits and efficacy in industrial wastewater treatment.

3D hierarchical graphene oxide-NiFe LDH composite with enhanced adsorption affinity to Congo red, methyl orange and Cr(VI) ions

Three-dimensional (3D) hierarchical graphene oxide-NiFe layered double hydroxide (GO-NiFe LDH) composite with sandwich-like structure is fabricated using a facile one-pot hydrothermal reaction. Electron microscopy images demonstrate that the GO-NiFe LDH composite possesses a highly porous and well-ordered structure. Both sides of the GO are fully covered by the LDH nanosheets, resulting in the sandwich-like architecture. The adsorption performance of the GO-NiFe LDH composite and pure NiFe LDH for three anionic pollutants, namely, Congo red (CR), methyl orange (MO) and hexavalent chromium ion [Cr(VI)] is systematically investigated. The presence of GO in the GO-NiFe LDH composite leads to the better adsorption capability and faster adsorption kinetics of this composite compared with the NiFe LDH microspheres. The pseudo-second-order kinetic model can well represent the adsorption kinetics, and the Langmuir isotherm model provides a better description for the adsorption isotherms. The GO-NiFe LDH composite demonstrates appreciable potential in alleviating anionic pollutants from the aquatic environment as shown by its excellent adsorption capability towards CR, MO and Cr(VI).

In Situ Synthesis of Mn3 O4 Nanoparticles on Hollow Carbon Nanofiber as High-Performance Lithium-Ion Battery Anode

The practical applications of Mn₃ O₄ in lithium-ion batteries are greatly hindered by fast capacity decay and poor rate performance as a result of significant volume changes and low electrical conductivity. It is believed that the synthesis of nanoscale Mn₃ O₄ combined with carbonaceous matrix will lead to a better electrochemical performance. Herein, a convenient route for the synthesis of Mn₃ O₄ nanoparticles grown in situ on hollow carbon nanofiber (denoted as HCF/Mn₃ O₄ ) is reported. The small size of Mn₃ O₄ particles combined with HCF can significantly alleviate volume changes and electrical conductivity; the strong chemical interactions between HCF and Mn₃ O₄ would improve the reversibility of the conversion reaction for MnO into Mn₃ O₄ and accelerate charge transfer. These features endow the HCF/Mn₃ O₄ composite with superior cycling stability and rate performance if used as the anode for lithium-ion batteries. The composite delivers a high discharge capacity of 835 mA h g^-1 after 100 cycles at 200 mA g^-1 , and 652 mA h g^-1 after 240 cycles at 1000 mA g^-1 . Even at 2000 mA g^-1 , it still shows a high capacity of 528 mA h g^-1 . The facile synthetic method and outstanding electrochemical performance of the as-prepared HCF/Mn₃ O₄ composite make it a promising candidate for a potential anode material for lithium-ion batteries.

High Performance Metal Oxide-Graphene Hybrid Nanomaterials Synthesized via Opposite-Polarity Electrosprays

An opposite-polarity electrospray technique is developed to synthesize Mn₃ O₄ -graphene hybrid nanomaterial that shows high specific capacity, fast charging/discharging capability, and long cycle life for lithium storage. The approach offers nanoparticle size control and tunability, morphology control, versatility for the synthesis of different materials and hybrid structures from different precursors, and continuous-flow nanomanufacturing with the potential for full automation.