Porous perovskite CaMnO3/rGO hybrid as an efficient electrocatalyst in lithium-oxygen batteries.

In this work, we demonstrate a facile route for synthesizing a novel CaMnO3/reduced graphene oxide (CaMnO3/rGO) nanohybrid as a cathode catalyst in Li-O2 batteries. The experimental results show that the CaMnO3/rGO hybrid exhibits superior electrochemical properties compared to bare CaMnO3 perovskite oxide. Li-O2 batteries assembled with a CaMnO3/rGO cathode catalyst show a remarkable initial discharge capacity of 19 000 mA h g-1 at a high current density of 1000 mA g-1. Excellent cycling stability is achieved within 200 cycles at a restricted charge/discharge capacity of 2000 mA h g-1. The enhanced catalytic performance proposes the hybrid of mesoporous CaMnO3 perovskite oxide and rGO nanosheets as a potential electrocatalyst for next-generation Li-O2 batteries.

The sweetness response and thermophysical properties of glucose and fructose in the aqueous solution of some deep eutectic solvents at T= (288.15-318.15) K.

Thermophysical properties elucidate the sweetness response, taste quality and hydration characteristics of saccharides in the aqueous solutions and offer significant information for pharmaceutical and food industries. In this current work, the effect of some neoteric green solvents as named deep eutectic solvents (DESs) on the sweetness response, taste quality and hydration behavior of the glucose and fructose solutions have been investigated from apparent specific volumes ASV, apparent specific isentropic compressibility ASIC parameters. The standard partial molar volumes Vφ0, transfer apparent molar volumes ΔtrVφ0, partial molar isentropic compressibilities Kφ0, viscosity B-coefficients and molar refractions RD the aqueous solutions of saccharides in choline chloride (ChCl)-urea, ChCl-ethylene glycol (EG), dimethyl ammonium chloride (DMAC)-ethylene glycol as DESs have been calculated from measured density, speed of sound, viscosity and refractive index data at T= (288.15-318.15) K. The results indicated that glucose in the aqueous solutions of ChCl-urea has the strongest interactions and get stronger with increasing the concentration of DES and temperature. Interaction volume Vint and cavity volume Vcav have been computed from scaled particle theory (SPT).

Low-cost nanowired α-MnO2/C as an ORR catalyst in air-cathode microbial fuel cell.

In this work, low cost α-MnO2 nanowires and α-MnO2 nanowires supported on carbon Vulcan (α-MnO2/C) have been synthesized via a simple and facile hydrothermal method for application in microbial fuel cells. The prepared samples have been characterized by X-ray diffraction (XRD), Raman spectroscopy and field emission scanning electron microscopy (FE-SEM). Electrocatalytic activities of the samples have been evaluated by means of cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in a neutral phosphate buffer solution. EIS was performed at different potentials to gain further insight into the kinetic properties of α-MnO2/C. Both catalysts were used in air cathode microbial fuel cells to achieve power densities of 180 and 111 mWm-2 for α-MnO2/C and pristine α-MnO2 nanowires, respectively. α-MnO2/C functions as a good and economical alternative for Pt free catalysts in practical MFC applications, as shown by the findings of stability test and voltage generation cycles in long-term operation of MFC.

High-performance asymmetric supercapacitor based on hierarchical nanocomposites of polyaniline nanoarrays on graphene oxide and its derived N-doped carbon nanoarrays grown on graphene sheets.

Activated carbon (AC), as a material for asymmetric supercapacitor (ASC), is the most widely used as negative electrode. However, AC has some electrode kinetic problems which are corresponded to inner-pore ion transport that restrict the maximum specific energy and power that can be attained in an energy storage system. Therefore, it is an important topic for researchers to extend the carbonaceous material with qualified structure for negative electrode supercapacitor. In this work, novel promoted ASC have been fabricated using nanoarrays of polyaniline grown on graphene oxide sheets (PANI-GO) as positive electrode and also, carbonized nitrogen-doped carbon nanoarrays grown on the surface of graphene (CPANI-G) as negative electrode. The porous structure of the as-synthesized CPANI-G can enlarge the specific surface area and progress ion transport into the interior of the electrode materials. From the other point of view, nitrogen doping can impressively improve the wettability of the carbon surface in the electrolyte and upgrade the specific capacitance by a pseudocapacitive effect. Because of the high specific capacitance and distinguished rate performance of PANI-GO and CPANI-G and moreover, the synergistic effects of the two electrodes with the optimum potential window, the ASC display excellent electrochemical performances. In comparison with the symmetric cell based on PANI-GO (40 Wh kg-1), the fabricated PANI-GO//CPANI-G ASC exhibits a remarkably enhanced maximum energy density of 52 Wh kg-1. Furthermore, ASC electrode exhibits excellent cycling durability, with 90.3% specific capacitance preserving even after 5000 cycles. These admirable results show great possibilities in developing energy storage devices with high energy and power densities for practical applications.