Binary mixed molybdenum cobalt sulfide nanosheets decorated on rGO as a high-performance supercapacitor electrode.

This work represents the production of MoS2/CoS2 hybridized with rGO as a material for high-performance supercapacitors. The hydrothermal method is used for the synthesis. The as-prepared material is characterized by x-ray diffraction spectroscopy, x-ray photoelectron spectroscopy, and electron microscopy. The size of the nanoparticles is estimated at 80 nm, and their uniform dispersion on rGO is observed from electron microscopy images. A high-specific capacitance of 190 mF cm-2 obtains for MoS2/CoS2/rGO at the current density of 0.5 mA cm-2 in 2 M KOH. The cyclic stability over 5000 cycles at a scan rate of 100 mV s-1 shows that the MoS2/CoS2/rGO electrode is stable, and 88.6% of its initial capacitance sustains at the end of 5000 cycles. This excellent performance is assigned to the synergistic effect of rGO and MoS2/CoS2. This electrode with excellent stability and capacitance could be a potential candidate for supercapacitor electrode materials.

Fe3O4@MoS2/RGO as an effective nano-electrocatalyst toward electrochemical hydrogen evolution reaction and methanol oxidation in two settings for fuel cell application.

A three-component nano-electrocatalyst, magnetite coated molybdenum disulfide hybridized with reduced graphene oxide (Fe3O4@MoS2/RGO), is synthesized by a two-step hydrothermal method. This catalyst is applied as an effective substitution for the platinum catalyst in methanol oxidation and hydrogen evolution reactions. Cyclic voltammetry, chronoamperometry, and linear sweep voltammetry are used to evaluate the performance of the electrocatalyst in acidic and basic media. The results of methanol oxidation reaction on the hybridized nano-electrocatalyst showed good electrocatalytic properties with considerable diffusion currents. This fact is confirmed by the Tafel plots and the calculated kinetic parameters of electron transfer. Fe3O4@MoS2/RGO showed an anodic transfer coefficient and exchange current of 0.464 and 4.80 × 10-8, respectively that are higher than Fe3O4/RGO. The presence of the porous MoS2 in catalyst has a key effect on supplying electroactive sites for electron transfer. Also, the high actual surface area obtained for the hybridized nano-electrocatalyst (A = 0.0295 cm2). The maximum power density of 35.03 mW cm-2 obtained for a single cell containing the prepared hybridized catalyst as the anode which shows a competitive feature of the synthetic catalyst compared to other reports. Furthermore, the synthetic catalyst shows the low-value overpotential of 108 mV and Tafel slope of 48 mV dec-1 during the hydrogen evolution process in acidic media. This is attributed to the synergistic effect between Fe3O4 and MoS2 and also increase the electron transfer rate due to adding conductive RGO to the catalyst. The results show that the synthetic nanocatalyst can have promising applications for hydrogen evolution and methanol oxidation reactions.

A sensitive biosensing method for detecting of ultra-trace amounts of AFB1 based on "Aptamer/reduced graphene oxide" nano-bio interaction.

A simple, low-cost and sensitive label-free aptasensor assembled with assisting reduced graphene oxide nanosheets as the signal amplifier was fabricated and applied for detecting ultra-low levels of Aflatoxin B1(AFB1) through a nano-bio interaction system. The conditions of different modified glassy carbon electrodes as the base of aptasensor were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The performance of the fabricated aptasensor was evaluated by FESEM, HRTEM and AFM images. The proposed biosensor detected AFB1sensitively in a wide linear range (0.5 nM-4µM) by DPV with a considerable low limit of detection (LOD = 0.07 nM) and good repeatability (RSD = 2.9) and stability. Finally, the present aptasensor was applied successfully for monitoring AFB1 with appropriate recoveries in pasteurized cow milk and human blood plasma as real samples.