Microwave-assisted synthesis of Mn3O4-Fe2O3/Fe3O4@rGO ternary hybrids and electrochemical performance for supercapacitor electrode

In the present work, the mechanism behind the functioning of the eco-friendly dye-sensitized solar cell was explored. Dye-sensitized solar cells were fabricated using natural dyes extracted from common pear (Opuntia dillenii) and red tamarind (Tamarindus indica), and 1:1 mixture. Betalain and anthocyanin were identified as the main pigments that sensitize the semiconductor TiO2 film. The best conversion efficiency of 0.47 % was achieved from betalain dyes and 0.14 % from anthocyanin dye-sensitized solar cell [under standard Air Mass 1.5 illumination (85 mW cm−2)]. The mixture of dye (1:1 mixture) adsorbed onto TiO2 exhibited an efficiency of 0.20 %. The light absorption behavior of extracted dyes was studied using ultraviolet–visible analysis. The influence of the binding nature of the dyes with TiO2 surface on the efficiency of the solar cells was analyzed through Fourier transform infra-red analysis. The electrochemical impedance spectroscopy was used to find out the internal charge transfer resistance of the cells. The device incident photon-to-current efficiency was obtained from 5 to 25 % for different natural dyes and found to coincide with the photocurrent–voltage characteristics and electrochemical impedance spectroscopy analysis.

Betalain and anthocyanin dye-sensitized solar cells

A review on carbon and non-precious metal based cathode catalysts in microbial fuel cells

Natural dyes, extracted from cherry, blackberry, blueberry, raspberry and strawberry fruits, were used as sensitizers to fabricate dye-sensitized solar cells (DSSCs). The conversion efficiency (η%) ranged from 0.14 to 0.69. Specifically, the highest η% was obtained from the dye extracted with ethanol 70% from blueberry fruit and epicarp (1.13 and 0.75, respectively), without other chemicals, pH adjustments and thermal or purification processes. The absorbance spectra of the dyes and their photoelectrochemical performances demonstrated that anthocyanins (ANCs) were the most effectual component of the sensitizer for DSSC. To check the affinity of the dyes for the TiO2 a new adsorption/desorption procedure was established. The comparison of the percentage distribution of each anthocyanin class in blueberry epicarp dye, before its adsorption and after its recovery from TiO2 powder, showed a better sensitizing performance of delphinidine derivatives compared to the other ANCs.

Role of pH and pigment concentration for natural dye-sensitized solar cells treated with anthocyanin extracts of common fruits

MXenes are the class of two-dimensional transition metal carbides and nitrides that exhibit unique properties and are used in a multitude of applications such as biosensors, water purification, electromagnetic interference shielding, electrocatalysis, supercapacitors, and so forth. Carbide-based MXenes are being widely explored, whereas investigations on nitride-based ones are seldom. Among the nitride-based MXenes obtained from their MAX phases, only Ti4N3 and Ti2N are reported so far. Herein, we report a novel synthesis of V2NT x (T x is the surface termination) obtained by the selective removal of "Al" from V2AlN by immersing powders of V2AlN in the LiF-HCl mixture (salt-acid etching) followed by sonication to obtain V2NT x (T x = -F, -O) MXene which is then delaminated using the dimethyl sulfoxide solvent. The V2NT x MXene is characterized by X-ray diffraction studies, field emission scanning electron microscope imaging, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscope imaging. Supercapacitor electrodes are prepared using V2NT x MXenes and their electrochemical performances are examined by cyclic voltammetry, galvanostatic charge/discharge measurement, and electrochemical impedance spectroscopy. The V2NT x MXene electrode exhibits a specific capacitance of 112.8 F/g at a current density of 1.85 mA/cm2 with an energy and power density of 15.66 W h/kg and 3748.4 W/kg, respectively, in 3.5 M KOH aqueous electrolyte. The electrode exhibits an excellent capacitance retention of 96% even after 10,000 charge/discharge cycles. An asymmetric supercapacitor fabricated with V2NT x as a negative electrode and Mn3O4 nanowalls as a positive electrode helps obtain a cell voltage of 1.8 V in aqueous KOH electrolyte.

New Method for the Synthesis of 2D Vanadium Nitride (MXene) and Its Application as a Supercapacitor Electrode.

Recent developments in manganese oxide based nanomaterials with oxygen reduction reaction functionalities for energy conversion and storage applications: A review

Review on manganese oxide based biocatalyst in microbial fuel cell: Nanocomposite approach

Physicochemical parameter influences and their optimization on the biosynthesis of MnO2 nanoparticles using Vernonia amygdalina leaf extract

Green synthesis of α -MnO2/NiO bimetallic nanocatalyst was achieved in the presence of Vernonia amygdalina leaf extract. The biosynthesized material was optimized by I-optimal Coordinate Exchange Design model by setting 3-operational factors under 9 experimental run. The optimum conditions were 51% nickel ion concentration, 25.3 min reaction time, and 75.3% (v/v) extract ratio to obtain a maximal absorption edge of 376.8 nm ( E g = 3 . 29 eV ) for a stable particle size estimation. The regression (R 2 = 0 .9873) and adjusted (R 2 = 0 .9494) coefficients as well as adequacy of precision (16.8772) proved the good correlation between actual and predicted values. Optical spectroscopies (UV–Vis and FTIR), XRD, DSC, SEM, surface roughness, CV, and EIS were performed to characterize the biosynthesized bimetallic nanocatalyst. Oxidation peak current response using bimetallic nanoparticles (NPs) modified electrode was 2.522 mA, which was higher than α -MnO2 (2.442 mA), NiO (1.897 mA), and bare pencil graphite (0.735 mA) electrodes. The corresponding conductivity of α -MnO2/NiO was higher with low solution resistance (10.84 Ω ) than other catalysts. As a result, the biosynthesized bimetallic modified pencil graphite electrode produces 412.24 ± 5.98 mW m − 2 maximum power density than bare pencil graphite (65.74 ± 0.96 mW m−2), α -MnO2 (315.62 ± 4.87 mW m−2), and NiO (140.35 ± 1.68 mW m−2) in the doubled chambered MFC. The results showed that the fabricated bimetallic NPs have an effective and value add role to modify conventional carbon anode electrodes in the MFCs energy conversion device system.

Bimetallic Mn–Ni oxide nanoparticles: Green synthesis, optimization and its low-cost anode modifier catalyst in microbial fuel cell

Microbial fuel cell (MFC) has novel technological advances in simultaneous power generation and wastewater treatment applications. In this study, low-cost biosynthesized α-MnO2 nanoparticles integr...

https://www.tandfonline.com/doi/pdf/10.1080/26895293.2021.1934123

Sisay Tadesse

Papers

Recent developments in manganese oxide based nanomaterials with oxygen reduction reaction functionalities for energy conversion and storage applications: A review

Review on manganese oxide based biocatalyst in microbial fuel cell: Nanocomposite approach

Physicochemical parameter influences and their optimization on the biosynthesis of MnO2 nanoparticles using Vernonia amygdalina leaf extract

Bimetallic Mn–Ni oxide nanoparticles: Green synthesis, optimization and its low-cost anode modifier catalyst in microbial fuel cell

Biosynthesized α-MnO2-based polyaniline binary composite as efficient bioanode catalyst for high-performance microbial fuel cell