MOF-Derived AlCuSe2 Embedded in a Carbon Matrix for an Economical Anode of Lithium-Ion Battery.

Binary metal chalcogenides (TMCs) have emerged as a potential candidate for lithium-ion batteries due to their availability, abundance, chemical properties, and high theoretical capacities. Despite these characteristics, they suffer from significant volume change, limited life cycle, and inferior rate capabilities which hinder their practical applications. These issues can be addressed by selecting low-cost nanostructure metal combinations coupled with a carbon matrix, which tackles significant volume change to give prolonged cycle life and high-rate capabilities. Herein, novel MOF-derived aluminum copper selenide (ACSe@C) nanospheres embedded in a carbon matrix are synthesized via a facile solvothermal route. Owing to their uniform porous structure, ACSe@C nanospheres exhibit excellent electrochemical performance as an anode material for Li-ion batteries. ACSe@C delivers a high specific capacity of 633.6 mAh g-1 at 0.1 A g-1 and a good rate capability of 532 mAh g-1 at 0.1 A g-1 and 400 mAh g-1 at 8 A g-1. This study demonstrates that ACSe@C is a good candidate for next-generation energy-storage devices.

Nanoengineering of NiO/MnO2/GO Ternary Composite for Use in High-Energy Storage Asymmetric Supercapacitor and Oxygen Evolution Reaction (OER).

Designing multifunctional nanomaterials for high performing electrochemical energy conversion and storage devices has been very challenging. A number of strategies have been reported to introduce multifunctionality in electrode/catalyst materials including alloying, doping, nanostructuring, compositing, etc. Here, we report the fabrication of a reduced graphene oxide (rGO)-based ternary composite NiO/MnO2/rGO (NMGO) having a range of active sites for enhanced electrochemical activity. The resultant sandwich structure consisted of a mesoporous backbone with NiO and MnO2 nanoparticles encapsulated between successive rGO layers, having different active sites in the form of Ni-, Mn-, and C-based species. The modified structure exhibited high conductivity owing to the presence of rGO, excellent charge storage capacity of 402 F·g-1 at a current density of 1 A·g-1, and stability with a capacitance retention of ~93% after 14,000 cycles. Moreover, the NMGO//MWCNT asymmetric device, assembled with NMGO and multi-wall carbon nanotubes (MWCNTs) as positive and negative electrodes, respectively, exhibited good energy density (28 Wh·kg-1), excellent power density (750 W·kg-1), and capacitance retention (88%) after 6000 cycles. To evaluate the multifunctionality of the modified nanostructure, the NMGO was also tested for its oxygen evolution reaction (OER) activity. The NMGO delivered a current density of 10 mA·cm-2 at the potential of 1.59 V versus RHE. These results clearly demonstrate high activity of the modified electrode with strong future potential.

In Situ Synthesis of a Polyaniline/ Fe-Ni Codoped Co3O4 Composite for the Electrode Material of Supercapacitors with Improved Cyclic Stability.

Conductive polymers have become a remarkable candidate for electrode materials of supercapacitors. Polyaniline (PANI) is the most promising contender for supercapacitors because of its easy method of synthesis, low cost, and higher choice in the improvement of energy storage applications. The main issue in the use of PANI in supercapacitors is its lower stability. In this work, PANI@Fe-Ni codoped Co3O4 (PANI@FNCO) nanocomposite has been prepared by in situ addition of 10 wt % FNCO as fillers in the PANI matrix. The nanocomposites were then characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry to observe the morphology, crystal structure, functional groups, and thermal stability of samples, respectively. SEM results showed that FNCO was fairly dispersed in the PANI matrix, while XRD results showed a broad peak for nanocomposites because of the semicrystalline nature of polymers. The electrochemical properties of the samples were analyzed via cyclic voltammetry, galvanostatic charge and discharge, and electrochemical impedance spectroscopy. PANI@FNCO nanowires are found to overcome the shortcomings in electrochemical energy storage devices by exhibiting a higher value of specific capacitance of 1171 F g-1 and energy density of 144 W h kg-1 at a current density of 1 A g-1. Moreover, the FNCO nanowires also showed a cyclic charge/discharge stability of 84% for 2000 cycles.

3D Hierarchically Mesoporous Zinc-Nickel-Cobalt Ternary Oxide (Zn0.6Ni0.8Co1.6O4) Nanowires for High-Performance Asymmetric Supercapacitors.

Increased efforts have been devoted recently to develop high-energy-density supercapacitors (SC) without renouncing their power efficiency. Herein, a hierarchically mesoporous nanostructure of zinc-nickel-cobalt oxide (ZNCO) nanowires (NWs) is constructed by hierarchical aggregation of ZNCO nanoparticles. It is worth noting that cobalt and nickel rich lattice imparts higher charge storage capability by enhanced reversible Faradaic reaction while zinc provides structural stability and higher conductivity. Moreover, particulate nature of ZNCO NWs allows deep diffusion of electrolyte thus enabling reversible charge storage under higher current densities. The as-prepared ZNCO NWs exhibited excellent specific capacitance of 2082.21 F g-1 at the current density of 1 A g-1 with high stability up to 5,000 charge-discharge cycles. Further, the asymmetric SC device was assembled using ZNCO NWs (ZNCO NWs//MWCNTs) which exhibited high energy density of 37.89 Wh kg-1 and excellent capacitance retention up to 88.5% over 1,000 cycles. This work presents ways to construct multi-component high-energy-density materials for next-generation energy storage devices.

Effective plant-endophyte interplay can improve the cadmium hyperaccumulation in Brachiaria mutica.

Soil contamination due to cadmium (Cd) is a ubiquitous environmental problem for which inexpensive remediation alternatives are required. Phytoaccumulation, the use of plants to extract and accumulate heavy metals from the contaminated environment, is such an alternative. In this study, we aimed at establishing effective plant-bacteria interplay between Brachiaria mutica and Cd-resistant endophytic bacteria eventually leading to improved phytoremediation. B. mutica was grown in a Cd-contaminated soil and inoculated with three Cd-tolerant endophytic bacteria individually as well as in combination. Plant physiological parameters, biomass production, bacterial colonization, and Cd-accumulation were observed at four different Cd exposures, i.e., 100, 200, 400 and 1000 mg kg-1 of soil. The combined application of endophytic bacteria was more effective as compared to their individual applications at all concentrations. Nevertheless, highest performance of consortium was seen at 100 mg Cd kg-1 of soil, i.e., root length was enhanced by 46%, shoot length by 62%, chlorophyll content by 40%, and dry biomass by 64%; which was reduced with the increase in Cd concentration. The bacterial population was highest in the root interior followed by rhizosphere and shoot interior. Concomitantly, plants inoculated with bacterial consortium displayed more Cd-accumulation in the roots (95%), shoots (55%), and leaves (44%). Higher values of BCFroot (> 1), and lower values for BCFshoot and TF (< 1) indicates capability of B. mutica to accumulate high amounts of Cd in the roots as compared to the aerial parts. The present study concludes that plant-endophyte interplay could be a sustainable and effective strategy for Cd removal from the contaminated soils.

Bacterial endophytes enhance phytostabilization in soils contaminated with uranium and lead.

The combined use of plants and bacteria is a promising approach for the remediation of polluted soil. In the current study, the potential of bacterial endophytes in partnership with Leptochloa fusca (L.) Kunth was evaluated for the remediation of uranium (U)- and lead (Pb)-contaminated soil. L. fusca was vegetated in contaminated soil and inoculated with three different endophytic bacterial strains, Pantoea stewartii ASI11, Enterobacter sp. HU38, and Microbacterium arborescens HU33, individually as well as in combination. The results showed that the L. fusca can grow in the contaminated soil. Bacterial inoculation improved plant growth and phytoremediation capacity: this manifested in the form of a 22-51% increase in root length, 25-62% increase in shoot height, 10-21% increase in chlorophyll content, and 17-59% more plant biomass in U- and Pb-contaminated soils as compared to plants without bacterial inoculation. Although L. fusca plants showed potential to accumulate U and Pb in their root and shoot on their own, bacterial consortia further enhanced metal uptake capacity by 53-88% for U and 58-97% for Pb. Our results indicate that the combination of L. fusca and endophytic bacterial consortia can effectively be used for the phytostabilization of both U- and Pb-contaminated soils.