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Herein, we report a facile hydrothermal synthesis of MnO₂ nanoparticles anchored multi walled carbon nanotubes (MnO₂@MWCNTs) as potential anode materials for lithium-ion (Li-ion) batteries. The prepared MnO₂@MWCNTs were characterized by several techniques which confirmed the formation of MnO₂ nanoparticles anchored MWCNTs. The X-ray diffraction and Raman-scattering analyses of the prepared material further revealed the effective synthesis of MnO₂@MWCNTs. The fabricated Li-ion battery based on MnO₂@MWCNTs exhibited a reversible capacity of ~823 mAhg -1 at a current density of 100 mAg -1 for the first cycle, and delivered a capacity of ~421 mAhg -1 for the 60 cycles. The coulombic efficiency was found to be ~100% which showed excellent reversible charge-discharge behavior. The outstanding performance of the MnO₂@MWCNTs anode for the Li-ion battery can be attributed to the distinctive morphology of the MnO₂ nanoparticles anchored MWCNTs that facilitated the fast transport of lithium ions and electrons and accommodated a broad volume change during the cycles of charge/discharge.

Nanotechnology has received much attention in treating contaminated waters. In the present study, a facile co-precipitation method was employed to synthesize a novel iron and magnesium based binary metal oxide using a stoichiometrically fixed amount of FeNO 3 ·9H 2 O and MgNO 3 ·6H 2 O in a proportion of molar concentration 1:1 and was later evaluated in removing As (III) from contaminated waters. Characterization of the prepared nanomaterial was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX) and ultraviolet-visible spectrophotometry (UV-VIS). Experimental studies on batch scale were carried out, examining the effect of varying initial concentrations of metal, adsorbent dosage, application time and initial pH on removal efficiency. Arsenic removal increased on increasing adsorbent dosage (0.1-1 g/L) but trend reversed on increasing initial arsenic concentration attaining q max of 263.20 mg/g. Adsorption was quite efficient in pH range 4-8. Freundlich fitted better for adsorption isotherm along with following Pseudo-2nd order kinetics. The reusability and effect of co-existing ions on arsenic adsorption, namely SO 4 2- , CO 3 2- and PO 4 3- were also explored with reusability in 1st and 2nd cycles attained adsorptive removal up to 77% and 64% respectively. The prepared nano-adsorbent showed promising results in terms of high arsenic uptake (q max of 263.20 mg/g) along with facile and cost-effective synthesis. Thus, the co-precipitation technique used in this work is a simple one step procedure without any use of any precursor as compared to most of the other procedures used for synthesis.

In this work, a simple and cost-effective electrochemical anodization technique was adopted to rapidly grow TiO 2 nanotube arrays on a Ti current collector and to utilize the synthesized materials as potential electrodes for supercapacitors. To accelerate the growth of the TiO 2 nanotube arrays, lactic acid was used as an electrolyte additive. The as-prepared TiO 2 nanotube arrays with a high aspect ratio were strongly adhered to the Ti substrate. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results confirmed that the TiO 2 nanotube arrays were crystallized in the anatase phase. TEM images confirmed the nanotublar-like morphology of the TiO 2 nanotubes, which had a tube length and a diameter of ~16 and ~80 nm, respectively. The electrochemical performance of the TiO 2 nanotube array electrodes was evaluated using the cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge (GCD) measurements. Excellent electrochemical response was observed for the electrodes based on the TiO 2 nanotube arrays, as the cells delivered a high specific capacitance of 5.12 mF/cm 2 at a scan rate of 100 mV/s and a current density of 100 µA/cm 2 . The initial capacity was maintained for more than 250 cycles. Further, a remarkable rate capability response was observed, as the cell retained 88% of the initial areal capacitance when the scan rate was increased from 10 to 500 mV/s. The results suggest the suitability of TiO 2 nanotube arrays as electrode materials for commercial supercapacitor applications.

We report a microwave irradiation method for the preparation of reduced graphene oxide (RGO) based Co 3 O 4 nanocomposites as anodes for lithium-ion (li-ion) batteries. The Co 3 O 4 /RGO nanocomposites displayed good electrochemical behavior as anodic materials for li-ion batteries when compared to pure Co 3 O 4 . The Co 3 O 4 /RGO nanocomposites with low RGO content resulted in stable electrochemical performance with 100% coulombic efficiency at a high current density of 500 mA/g for 50 cycles. The enhanced capacity of the Co 3 O 4 /RGO nanocomposites is due to the incorporation of RGO, which resulted in a four times larger surface area than that of Co 3 O 4 . This increased surface area could facilitate the absorption of more lithium ions, resulting in excellent electrochemical performance. Interestingly, the novelty of this work is that the designed li-ion batteries showed stable electrochemical performance even at a high temperature of 100 °C, which might be useful for rechargeable battery applications in a wide temperature range.

In this work, holey reduced graphene oxide (HRGO) was synthesized by the deposition of silver (Ag) nanoparticles onto the reduced graphene oxide (RGO) sheets followed by nitric acid treatment to remove Ag nanoparticles by microwave irradiation to form a porous structure. The HRGO were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultra violet-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), and Raman spectroscopy. These novel HRGO exhibited high rate capability with excellent cycling stability as an anode material for lithium-ion batteries. The results have shown an excellent electrochemical response in terms of charge/discharge capacity (423 mAh/g at 100 mA/g). The cyclic performance was also exceptional as a high reversible capacity (400 mAh/g at 100 mA/g) was retained for 100 charge/discharge cycles. This fascinating electrochemical performance can be ascribed to their specific porous structure (2-5 nm pores) and high surface area (457 m(2)/g), providing numerous active sites for Li(+) insertion, high electrical conductivity, low charge-transfer resistance across the electrolyte-electrode interface, and improved structural stability against the local volume change during Li(+) insertion-extraction. Such electrodes are envisioned to be mass scalable with relatively simple and low-cost fabrication procedures, thereby providing a clear pathway toward commercialization.