Laser Scribed Graphene from Oil Palm Lignin for Supercapacitor Applications

This paper reports a facile carbonization method of a biopolymer to synthesize reduced graphene oxide with excellent electrochemical properties for use as a supercapacitor electrode. Oil palm lignin is used as the biopolymer-based graphene precursor, and a carbon dioxide laser is used to carbonize the material via lithography. Using Raman Spectroscopy, the characterization of the resultant graphene (OP-LSG) revealed D, G, and 2D peaks corresponding to multilayer graphene. Scanning Electron Microscopy of OP-LSG revealed three-dimensional particle-like fibrous and porous nanostructures with an enhanced surface area. In a three-electrode setup in ferrocyanide electrolyte, cyclic voltammetry showed the electrode coated with OP-LSG achieving a specific capacitance as high as 108.044 mF/cm² at a scan rate of 0.01 V/s. The galvanostatic charge-discharge of OP-LSG revealed energy and power density values of 15 µWh/cm² and 597 µW/cm² at a scan rate of 0.01 V/s. The OP-LSG electrode retained 97.5% of its initial capacitance after 1000 charge-discharge cycles

Characterizations of synthesized laser scribed graphene/molybdenum disulfide (LSG/MoS2) hybrids for supercapacitor performance

A sustainable and organic energy storage system from oil palm lignin waste-derived laser-scribed graphene embedded with molybdenum disulfide (LSG/MoS2) is reported in this work. LSG/MoS2 hybrids were fabricated to overcome the zero-band gap of graphene, and molybdenum disulfide restacking issues, and to induce electrical conductivity. Various amounts of LSG (0.1,0.5,1.0 g) were added in a MoS2 precursor to produce a nanoscale LSG/MoS2 hybrid nanostructure via the hydrothermal method. The Raman D,G, and 2D bands of LSG confirmed the formation of graphene from lignin. The FESEM morphology of LSG/MoS2 hybrids showed a porous and large surface area anchored with 3D MoS2 nanoflower on LSG. TEM imaging revealed MoS2 decorated LSG with a lattice spacing of 0.62 and 0.27nm, corresponding to the (002) and (100) planes of MoS2. In terms of electrochemical performance, LSG with 0.1g of MoS2 has the lowest resistance, the highest specific capacitance of 6.7mF/cm2 at 0.05 mA/cm2, and excellent cyclic stability of 98.1% over 1000 cycles, based on Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV) and Galvanostatic Charge Discharge (GCD) tests

STUDIES ON THE INHIBITIVE EFFECT OF DATURA STRAMONIUM EXTRACT ON THE ACID CORROSION OF MILD STEEL

The extract of Datura stramonium has been studied as a possible source of green inhibitor for corrosion of mild steel (MS) in HCl and H2SO4 media at different temperatures. The anticorrosion effect was evaluated by conventional weight loss studies, electrochemical studies viz., Tafel polarization, ac impedance, and SEM studies. The studies reveal that the plant extract acts as a good inhibitor in both the acid media and better in H2SO4 medium. Tafel polarization method indicate that the plant extract behaves as a mixed mode inhibitor. Double layer capacitance and charge transfer resistance values derived from Nyquist plots obtained from ac impedance studies give supporting evidence for the anticorrosive effect. The inhibitive effect may be attributed to the adsorption of the inhibitor on the surface of MS, following Temkin adsorption isotherm. Increase of inhibition efficiency with increase of temperature along with Ea values serve as a proof for chemisorption. SEM studies provide the confirmatory evidence for the protection of MS by the green inhibitor. The study reveals the potential of D. stramonium for combating corrosion which may be due to the adsorption of alkaloids and other phytoconstituents.Datura stramonium, corrosion inhibitor, electrochemical studies, chemisorption

Properties of contaminated reinforced concrete added by Areca catechu leaf extract as an eco-friendly corrosion inhibitor

The main reason causing the degeneration of steel-reinforced concrete is supposed to be corrosion of reinforcement steel. In this study, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), and weight loss have been utilized to evaluate the corrosion of steel reinforcement in contaminated, chemical inhibitor (sodium nitrite) and green inhibitor (Areca catechu extract)-added concrete. Besides, ultrasonic pulse velocity, sulfate and acid attack resistance, heat of hydration, and specific heat capacity tests have been performed to investigate the effect of inhibitor addition on permeability and durability of corrosion inhibitor-added samples. The concrete contaminated with 5% of Magnesium Sulfate (MgSO4) and Sodium Chloride (NaCl) as corrosion stimulant. The results showed that Areca catechu was more corrosive than sodium nitrite. Further, there was no gypsum found visible in SEM observation for Areca catechu-added concrete. The green and chemical inhibitor-modified samples could improve the specific heat capacity behavior of contaminated concrete by 10.77% and 13.25%, respectively. Areca catechu could decrease the corrosion rate of contaminated concrete about 30%, even in an extreme harsh environment applied in the current study. Polarization analysis depicted that Areca catechu extract acted as a mixed-type inhibitor

Mechanical properties of contaminated concrete inhibited by Areca catechu leaf extract as a green corrosion inhibitor

The most significant characteristic of corrosion inhibitors is to create chemical stability, when considering the fact that it affects concrete properties simultaneously. mild steel corrosion in 1 M HCl was studied in the presence different concentrations of Acacia longifolia, Areca catechu, Melastoma malabathricum, Elaeis guineensis and Cocos nucifera as green inhibitors and sodium nitrite (SN) as chemical inhibitor. Effects of green inhibitor utilized in this research has been investigated through conducting various tests on ordinary concrete, contaminated concrete and contaminated concrete modified with SN inhibitor and Areca catechu was found as the most efficient green inhibitor which was concluded through corrosion of mild steel and nitrogen content tests. The ordinary concrete has been contaminated by adding 5% magnesium sulphate and 5% sodium chloride by mixing water while casting. Results showed that the optimum percentage of A. catechu over concrete was 2% achieved by compressive, tensile and flexural strength test has been conducted at 7 and 28 days. Both chemical and green inhibitor showed acceptable compressive, tensile and flexural strength in contaminated concrete, while A. catechu added concrete showed superior performance when compared to SN

Areca Catechu: An eco-friendly corrosion inhibitor for reinforced concrete structures in corrosive mediums

The main reason causing the degeneration of steel reinforced concrete supposed to be corrosion of reinforcement steel. In this study, compressive strength, weight loss and field emission scanning electron microscopy (FESEM) were performed in order to investigate about the changes due to addition of 2% bio-friendly and chemical inhibitors per cement weight on corrosion of reinforced concrete mixed with 5% of NaCl and MgSO4 as corrosive materials. The results showed that Areca Catechu added sample revealed a dense texture clustered formation of gypsum. The samples with corrosion inhibitors had relatively more homogeneous surfaces and exhibited a smoother structure

Benzimidazole-loaded Halloysite Nanotube as a Smart Coating Application

Smart coating has been developed for the corrosion control of surfaces exposed to corrosive environment. An important step in development of a smart coating is the successful impregnation of corrosion inhibitor into the nanocontainer as a coating pigment. In this study, halloysite was used as nanocontainer to encapsulate benzimidazole as corrosion inhibitor by vacuum method. FESEM, TEM, FTIR and TGA characterization techniques were used to confirm the loading of halloysite with benzimidazole. FESEM results indicated differences between the morphology of the unloaded-halloysite and benzimidazole loaded-halloysite. TEM results confirmed that benzimidazole molecules are loaded into halloysite. FTIR result revealed there are differences in the absorbance characteristic of peaks between peak number 1000-4000 cm-1 for loaded and unloaded samples. It is seen that the absorbance in the loaded-halloysite is higher than unloaded-halloysite, which confirms quantity/specific functional group of molecules. TGA result showed the temperature of degradation of benzimidazole-loaded HNT was higher than pure HNT. EIS was conducted to examine the protection characteristic of the developed smart coating. From EIS results, of 1, 3, and 6 days of experimental duration, it is seen that the value of coating impedance (Z’) after exposure to 3.5% NaCl environment is very height, 2.460E+07 Ω, which confirm a very good anti corrosion protection characteristic for the developed smart coating.

Enhanced corrosion resistance of reinforced concrete: role of emerging eco-friendly Elaeis guineensis/silver nanoparticles inhibitor

Silver nanoparticles (AgNPs) doped palm oil leaf (Elaeis guineensis/EG) extracts (EG/AgNPs) were prepared as novel, non-toxic, and eco-friendly corrosion inhibitor; which were incorporated in cement composite and examined against reinforcement steel corrosion in natural seawater. Standard corrosion monitoring techniques including linear polarization resistance (LPR), potentiodynamic polarisation, half-cell potential (HCP) and electrical resistivity were used to screen corrosion inhibition potential of EG/AgNPs enabled steel reinforced concrete after exposing them weekly to wet and dry cycles in seawater. Besides, the microstructural, morphological, thermal and elemental properties of such concrete at 365 days of exposure were determined. The microstructures of powder of EG/AgNPs inhibitor, pre- and post-treated concrete (powder and small pieces) as well as the steel reinforcement surface were analysed. Incorporation of 5% green EG/AgNPs inhibitor into the steel reinforced concrete revealed enhanced corrosion resistance, where a protective thin barrier was developed over the steel reinforced surface. This improvement was attributed to the formation of extra calcium silicate hydrate (C-S-H) gel in the concrete and thereby blocked the concrete pores. The maximum inhibition efficiency was recorded to be as much as 94.74%. It is established that these green EG/AgNPs has prospective for optimum corrosion inhibiting treatment to achieve durable concrete structures

Gum arabic nanoparticles as green corrosion inhibitor for reinforced concrete exposed to carbon dioxide environment

10.3390/ma14247867Materials1424786

A Comprehensive Review on Biopolymer Mediated Nanomaterial Composites and Their Applications in Electrochemical Sensors

Biopolymers are an attractive green alternative to conventional polymers, owing to their excellent biocompatibility and biodegradability. However, their amorphous and nonconductive nature limits their potential as active biosensor material/substrate. To enhance their bio-analytical performance, biopolymers are combined with conductive materials to improve their physical and chemical characteristics. We review the main advances in the field of electrochemical biosensors, specifically the structure, approach, and application of biopolymers, as well as their conjugation with conductive nanomaterials, polymers, and metal oxides in green-based non-invasive analytical biosensors. In addition, we reviewed signal measurement, substrate bio-functionality, biochemical reaction, sensitivity, and limit of detection (LOD) of different biopolymers on various transducers. To date, pectin biopolymer, when conjugated with either gold nanoparticles, polypyrrole, reduced graphene oxide, or multiwall carbon nanotubes forming nanocomposites on glass carbon electrode transducer, tends to give the best LOD, highest sensitivity, and can detect multiple analytes/targets. This review will spur new possibilities for the use of biosensors for medical diagnostic tests