Synergistic effect of MoS2 and Fe3O4 decorated reduced graphene oxide as a ternary hybrid for high-performance and stable asymmetric supercapacitors

Boron and nitrogen co-doped carbon nanospheres for supercapacitor electrode with excellent specific capacitance

At present, carbon materials derived from biomass precursors have many limitations in the field of energy storage. In this study, boron and nitrogen (B/N) co-doped carbon nanospheres are successfully prepared by emulsion crosslinking method using chitosan and boric acid as raw materials. After carbonization at high temperature, the carbon nanospheres can be facilely prepared with controllable particle size, showing excellent structural stability and sphericity. In addition, the heteroatoms co-doping endows the carbon nanospheres with large specific surface area, high graphitization degree and excellent electrochemical performance. Applying the carbon nanospheres for supercapacitors, the specific capacitance can reach up to 336.7 F g^-1at a current density of 1 A g^-1. Even after 10,000 cycles, the Coulomb efficiency and specific capacitance still remain at 98.61% and 96.8%, respectively, demonstrating the great promise of B/N co-doped carbon nanospheres for the state-of-the-art supercapacitor electrodes applications.

End of life analysis of solar photovoltaic panel: roadmap for developing economies

Purpose

The purpose of this paper is to propose a conceptual framework for handling end of life (henceforth EoL) scenarios of solar photovoltaic (solar PV) panels, which includes different options available to businesses and end-users, as well as promoting the collaboration between government and all relevant stakeholders.

Design/methodology/approach

This paper adopts purposeful sampling, secondary data and content analysis to develop an appropriate conceptual framework that helps to create awareness of the appropriate options for dealing with the EoL cases of solar PV panels.

Findings

From the data analysis, it is revealed that reuse, repair and recycling of solar PV panels can ensure value creation, public-private partnership and a solution for education in sustainability, and thus, prolonging the useful life cycle of the products.

Research limitations/implications

This paper limits the analysis on developing economies and the use of selected literature based on the recycling of solar PV panels.

Originality/value

This paper is an initial attempt to create an awareness by identifying, analyzing and educating the stakeholders to handle appropriately any EoL scenario of solar PV panels.

Enhanced electrochemical performance of MnNi2O4/rGO nanocomposite as pseudocapacitor electrode material and methanol electro-oxidation catalyst

Binary transition metal oxides with encouraging electrocatalyst properties have been suggested as electrode materials for supercapacitors and methanol oxidation. Hence, in this work, a binary mixed metal oxide based on nickel and manganese (MnNi₂O₄) and its hybrid with reduced graphene oxide were synthesized by a one-step hydrothermal method. After physical and morphological characterization, the potential of these nanostructures was investigated for use as supercapacitor electrodes and methanol electro-oxidation. The results of the electrochemical analysis showed a substantial effect of adding rGO to the MnNi₂O₄. The MnNi₂O₄/rGO hybrid electrode supercapacitor exhibited good stability of 93% after 2000 consecutive CV cycles and a specific capacitance of 575 F g^-1at the current density of 0.5 A g^-1. Furthermore, the application of this hybrid nanomaterial in the methanol electro-oxidation reaction (MOR) indicated its appropriate electrochemical efficiency and stability in methanol oxidation. Our results show that MnNi₂O₄/rGO can be considered as a promising electrode material for energy applications.

Electrochemical determination of rutin by using NiFe2O4 nanoparticles-loaded reduced graphene oxide

A binary transition metal oxide containing nickel and iron (NiFe2O4) and hybridization of this nanomaterial with reduced graphene oxide (rGO) are synthesized by the hydrothermal method. X-ray diffraction (XRD) and Raman spectroscopy confirm the successful synthesis of these materials. Also, scanning electron microscope (SEM) and transmission electron microscope (TEM) images illustrated the particle morphology with the particle size of 20 nm. The synthesized material is then examined as a sensor on the surface of the glassy carbon electrode to detect a very small amount of rutin. Some electrochemical tests such as cyclic voltammetry, differential pulse voltammetry (DPV), and impedance spectroscopy indicate the remarkable accuracy of this sensor and its operation in a relatively wide range of concentrations of rutin (100 nM-100 µM). The accuracy of the proposed electrochemical sensors is approximately 100 nM in 0.1 M PBS, (pH = 3) which is relatively impressive and can be reported. Also, the stability rate after 100 DPV was about 95 %, which is a considerable and relatively excellent value. Considering the very good results, it seems that the NiFe2O4-rGO can be considered as a new proposal in the development of accurate and inexpensive electrochemical sensors.