From PET Bottles Waste to N-Doped Graphene as Sustainable Electrocatalyst Support for Direct Liquid Fuel Cells

Direct liquid fuel cells represent one of the most rapidly emerging energy conversion devices. The main challenge in developing fuel cell devices is finding low-cost and highly active catalysts. In this work, PET bottle waste was transformed into nitrogen-doped graphene (NG) as valuable catalyst support. NG was prepared by a one-pot thermal decomposition process of mineral water waste bottles with urea at 800 °C. Then, NG/Pt electrocatalysts with Pt loadings as low as 0.9 wt.% and 1.8 wt.% were prepared via a simple reduction method in aqueous solution at room temperature. The physical and electrochemical properties of the NG/Pt electrocatalysts are characterized and evaluated for application in direct borohydride peroxide fuel cells (DBPFCs). The results show that NG/Pt catalysts display catalytic activity for borohydride oxidation reaction, particularly the NG/Pt_1, with a number of exchanged electrons of 2.7. Using NG/Pt composite in fuel cells is anticipated to lower prices and boost the usage of electrochemical energy devices. A DBPFC fuel cell using NG/Pt_1 catalyst (1.8 wt.% Pt) in the anode achieved a power density of 75 mW cm−2 at 45 °C. The exceptional performance and economic viability become even more evident when expressed as mass-specific power density, reaching a value as high as 15.8 W mgPt−1

Identification of the surface species in electrochemical promotion: ethylene oxidation over a Pt/YSZ catalyst

The electrochemical promotion of the C2H4 + O2 total oxidation reaction over a Pt catalyst, interfaced to yttrium stabilized zirconia (YSZ), has been studied at 0.25 mbar and T = 650 K using near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) as an in situ method. The electrochemical promoter effect is linked to the presence of a several layers thick graphitic overlayer that forms on the Pt surface in the presence of C2H4. Our NAP-XPS investigation reveals that electrochemical pumping of the Pt/YSZ catalyst, using a positive potential, leads to the spillover of oxygen surface species from the YSZ support onto the surface of the Pt electrode. Based on the XP spectra, the spillover species on Pt is identical to oxygen chemisorbed from the gas-phase

Ambient pressure X ray photoelectron spectroscopy during electrochemical promotion of ethylene oxidation over a bimetallic Pt Ag YSZ catalyst

The electrochemical promotion of the C2H4 + O2 reaction over a bimetallic Pt/Ag catalyst (Pt:Ag ratio ≈ 1.5) interfaced to yttrium stabilized zirconia (YSZ) has been studied at 0.25 mbar and T = 650 K using X-ray photoelectron spectroscopy as in situ method. Applying a positive potential of 2 V causes a relative rate increase in the CO2 production up to 120%; the electrocatalytic promotion effect is non-Faradaic (Λ ≈ 2). An electrochemical promotion is found to occur only at high enough p(C2H4) when a carbonaceous CHx layers builds up inhibiting O2 adsorption. The CHx film is estimated to be about 5–6 layers thick. Only at low p(C2H4), the application of an electric potential causes a decrease in the carbon signal associated with a growth of the O1s signal at 529.3 eV. The latter species can be assigned to an electrochemically generated oxygen spillover species at Ag sites

Identification of the surface species in electrochemical promotion ethylene oxidation over a Pt YSZ catalyst

The electrochemical promotion of the C2H4 O2 total oxidation reaction over a Pt catalyst, interfaced to yttrium stabilized zirconia YSZ , has been studied at 0.25 mbar and T 650 K using near ambient pressure X ray photoelectron spectroscopy NAP XPS as an in situ method. The electrochemical promoter effect is linked to the presence of a several layers thick graphitic overlayer that forms on the Pt surface in the presence of C2H4. Our NAP XPS investigation reveals that electrochemical pumping of the Pt YSZ catalyst, using a positive potential, leads to the spillover of oxygen surface species from the YSZ support onto the surface of the Pt electrode. Based on the XP spectra, the spillover species on Pt is identical to oxygen chemisorbed from the gas phas

Design of Promising Green Cation-Exchange-Membranes-Based Sulfonated PVA and Doped with Nano Sulfated Zirconia for Direct Borohydride Fuel Cells

The direct borohydride fuel cell (DBFC) is a low-temperature fuel cell that requires the development of affordable price and efficient proton exchange membranes for commercial purposes. In this context, super-acidic sulfated zirconia (SO4ZrO2) was embedded into a cheap and environmentally friendly binary polymer blend, developed from poly(vinyl alcohol) (PVA) and iota carrageenan (IC). The percentage of SO4ZrO2 ranged between 1 and 7.5 wt.% in the polymeric matrix. The study findings revealed that the composite membranes’ physicochemical features improved by adding increasing amounts of SO4ZrO2. In addition, there was a decrease in the permeability and swelling ratio of the borohydride membranes as the SO4ZrO2 weight% increased. Interestingly, the power density increased to 76 mW cm−2 at 150 mA cm−2, with 7.5 wt.% SO4ZrO2, which is very close to that of Nafion117 (91 mW cm−2). This apparent selectivity, combined with the low cost of the eco-friendly fabricated membranes, points out that DBFC has promising future applications

Design, Synthesis and Evaluation of Novel Antimicrobial Polymers Based on the Inclusion of Polyethylene Glycol/TiO₂ Nanocomposites in Cyclodextrin as Drug Carriers for Sulfaguanidine

Polymers and their composites have recently attracted attention in both pharmaceutical and biomedical applications. Polyethylene glycol (PEG) is a versatile polymer extensively used in medicine. Herein, three novel PEG-based polymers that are pseudopolyrotaxane (PEG/α-CD) (1), titania–nanocomposite (PEG/TiO2NPs) (2), and pseudopolyrotaxane–titania–nanocomposite (PEG/α-CD/TiO2NPs) (3), were synthesized and characterized. The chemical structure, surface morphology, and optical properties of the newly materials were examined by FT-IR, 1H-NMR, SEM, and UV–Vis., respectively. The prepared polymers were used as drug carriers of sulfaguanidine as PEG/α-CD/Drug (4), PEG/TiO2NPs/Drug (5), and PEG/α-CD/TiO2NPs/Drug (6). The influence of these drug-carrying formulations on the physical and chemical characteristics of sulfaguanidine including pharmacokinetic response, solubility, and tissue penetration was explored. Evaluation of the antibacterial and antibiofilm effect of sulfaguanidine was tested before and after loading onto the prepared polymers against some Gram-negative and positive bacteria (E. coli, Pseudomonas aeruginosa, and Staphylococcus aureus (MRSA)), as well. The results of this work turned out to be very promising as they confirmed that loading sulfaguanidine to the newly designed polymers not only showed superior antibacterial and antibiofilm efficacy compared to the pure drug, but also modified the properties of the sulfaguanidine drug itself

Synthesis of Ag Nanoparticles-Decorated CNTs via Laser Ablation Method for the Enhancement the Photocatalytic Removal of Naphthalene from Water

Silver nanoparticles (Ag NPs) were decorated with different amounts on the exterior walls of carbon nanotubes (CNTs) by a laser ablation assisted method, especially in liquid media to be applied as a good adsorption material against naphthalene. The laser ablation time was controlled the amount of decoration Ag NPs on CNTs. The prepared nanocomposite was analyzed via different analytical techniques. Ag NPs with a small size distribution of 29 nm are uniformly decorated with spherical shape on CNTs walls. The disorder degree of tubular structure and shifting of the vibrational characteristic peaks increase with the increase in the decoration of Ag NPs. After that, the prepared samples were investigated for the removal of naphthalene. These studies of loading Ag NPs with different amounts on the surface of CNTs act as a promising material for water treatment

Thermal evolution of cobalt deposits on Co3O4(111): atomically dispersed cobalt, two-dimensional CoO islands, and metallic Co nanoparticles

Cobalt oxide nanomaterials show high activity in several catalytic reactions thereby offering the potential to replace noble metals in some applications. We have developed a well-defined model system for partially reduced cobalt oxide materials aiming at a molecular level understanding of cobalt-oxide-based catalysis. Starting from a well-ordered Co3O4(111) film on Ir(100), we modified the surface by deposition of metallic cobalt. Growth, structure, and adsorption properties of the cobalt-modified surface were investigated by scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and infrared reflection absorption spectroscopy (IRAS) using CO as a probe molecule. The deposition of a submonolayer of cobalt at 300 K leads to the formation of atomically dispersed cobalt ions distorting the surface layer of the Co3O4 film. Upon annealing to 500 K the Co ions are incorporated into the surface layer forming ordered two-dimensional CoO islands on the Co3O4 grains. At 700 K, Co ions diffuse from the CoO islands into the bulk and the ordered Co3O4(111) surface is restored. Deposition of larger amounts of Co at 300 K leads to formation of metallic Co aggregates on the dispersed cobalt phase. The metallic particles sinter at 500 K and diffuse into the bulk at 700 K. Depending on the degree of bulk reduction, extended Co3O4 grains switch to the CoO(111) structure. All above structures show characteristic CO adsorption behavior and can therefore be identified by IR spectroscopy of adsorbed CO

Development of an efficient, low-operating-pressure graphene oxide / polyethersulfone nanofiltration membrane for removing various water contaminants

Conventional wastewater treatment technologies tend to be high-capex, energy-intensive solutions that lack specificity for different pollution classes, and do not lend themselves to wide-scale deployment, particularly in areas of the world where industrial wastewater discharge is a significant environmental problem. In tandem, solid waste pollution arising, particularly plastic containing waste, is a persistent and serious pollution issue. This work focuses on the concept of "waste treating waste" and a multidisciplinary effort ranging from materials science and environmental management to sustainable water treatment, in addition to production of graphene oxide from mineral water waste bottles using a simple synthetic procedure that can be economically scaled up for use as a cost-effective adsorbent. Prepared graphene oxide was supported on a polyethersulfone (PES) membrane, and batch filtration studies were performed to examine its performance in the removal of methylene blue (MB) dye, Gentimicin sulphate (GMS) antibiotic, and Na2SO4 and MgSO4 salts from an aqueous solution. Operating parameters such as initial pollutant concentration, time, and solution pH were investigated and optimized using a response surface methodology (RSM) model. The results confirm the significant efficiency of the filtration process, with a maximum rejection of about 91% for MB, 93% for GMS, 67% for Na2SO4, and 64% for MgSO4, with maximum water flux of 1322, 1367, 1225, and 1059 LMH, respectively. Density functional theory calculations were considered for the GO, PES membrane, and GO/PES membrane with a GGA/PBE optimization level. Adsorption annealing locator analysis was performed for the GO/PES membrane, and the process was recalculated for MB as adsorbate. In conclusion, the adsorption effect employing produced GO/PES membrane is the most important removal, followed by Donnan exclusion and steric hindrance effect. Therefore, it is possible to build new eco-friendly membranes for nanofiltration that are affordable, stable, and effective in removing various pollutants from water systems

Experimental and Computational Exploration of Chitin, Pectin, and Amylopectin Polymers as Efficient Eco-Friendly Corrosion Inhibitors for Mild Steel in an Acidic Environment: Kinetic, Thermodynamic, and Mechanistic Aspects

Herein, the inhibition impacts of chitin, pectin, and amylopectin as carbohydrate polymers on the corrosion of mild steel in 0.5 M HCl were researched utilizing various experimental and theoretical tools. The acquired outcomes showed that the inhibition efficiencies (% IEs) of the tested carbohydrate polymers were increased by raising their concentrations and these biopolymers acting as mixed-kind inhibitors with major anodic ones. The acquired % IEs values were reduced with rising temperature. The higher % IEs of the tested polymers were inferred via powerful adsorption of the polymeric molecules on the steel surface and such adsorption obeyed the Langmuir isotherm. The computed thermodynamic and kinetic quantities confirmed the mechanism of physical adsorption. The kinetics and mechanisms of corrosion and its protection by polymeric compounds were illuminated. The results obtained from all the techniques used confirmed that there was good agreement with each other, and that the % of IEs followed the sequence: chitin > amylopectin > pectin