5 research outputs found
Exploring the Enhanced Catalytic Activity of Pt Nanoparticles Generated on the Red Phosphorus/Graphitic Carbon Nitride Binary Heterojunctions in the Photo-assisted Hydrolysis of Ammonia Borane
No full textAmmonia borane (AB) holds great promise for chemical
hydrogen storage,
but its slow dehydrogenation kinetics under ambient conditions requires
a suitable catalyst to facilitate hydrogen production from AB. Here,
we fabricated binary red phosphorus/graphitic carbon nitride (RP/g-CN)
heterojunctions decorated with Pt nanoparticles (NPs, denoted Pt/RP/g-CN)
with a facile ultrasound-assisted two-step protocol as a photo-assisted
catalyst for the hydrolysis of AB (HAB). The heterojunction established
through intimate P–O–N bonds was proven to have improved
photophysical properties such as a lower electron–hole recombination
and enhanced visible light utilization compared to the pristine components.
With the incorporation of Pt NPs, the optical properties of RP/g-CN
heterojunctions were further improved through Schottky junction formation
between semiconductors and Pt NPs, enabling a superb hydrogen gas
(H2) generation rate of 142 mol H2·mol
Pt–1·min–1 under visible
light irradiation. Even though g-CN is a well-known host material
for many metal NPs, here we discovered that the interaction of Pt
NPs with RP in the ternary heterojunction structure is more favorable
than that of g-CN, stressing the key role of RP as a support material
in the designed ternary heterostructure. The band alignment of the
ternary heterojunction catalyst along with the flow of charge carriers
was also studied and shown to be a type-II heterojunction structure
without hole migration, namely, a complex type-II heterojunction.
Several scavenger experiments were also conducted to explain the mechanism
of the photo-assisted HAB. To the best of our knowledge, this is the
first example of a dual mechanism proposed for the visible light-assisted
HAB. While the majority of the H2 was believed to be produced
on the Pt NPs surface with the traditional B–N bond dissociation
mechanism, the strong oxidizing action of OH• radicals
formed by the heterojunction photocatalyst was also speculated to
account for the 33% increase in the activity upon visible light irradiation
through another mechanism
Facile synthesis of Co/rGO, Au/rGO, and CoAu/rGO nanocomposites for precise determination of Arsenic(III) in water systems
No full textCobalt (Co), gold (Au), and cobalt-gold (CoAu) nanoparticles were deposited on reduced graphene oxide (rGO) by a facile and scalable procedure. The synthesised nanocomposites (Co/rGO, Au/rGO, and CoAu/rGO) were used as electrode materials for detecting trace amounts of arsenic (As(III)) ions in water samples. All three electrodes responded to the presence of As(III) in an acidic medium (different acids of the same concentration, then chosen acid at different concentrations). A detailed optimization of the conditions was continued with the CoAu/rGO electrode which showed the best response in terms of the best defined peak indicating the oxidation of As(0) to As(III) and the highest current. The electrode was tested in a wide range of concentrations (30–1000 µM), where two areas of linearity and limits of detection were obtained (for low- and high- concentrations). Moreover, this electrode showed the ability to detect As(III) ions in the presence of Cu(II), as an interference model as well as a satisfactory electrochemical response, in terms of a clear peak corresponding to the oxidation of As(0) to As(III) in a real sample
Analytical performance and stability studies of CoAu/rGO-based electrochemical sensor for arsenic(III) detection in aqueous solutions
No full textCobalt-gold nanoparticles (CoAu) were grafted on reduced graphene oxide (rGO) using a simple and scalable procedure. As-prepared CoAu/rGO nanocomposites were employed as electrode materials to detect trace amounts of arsenic(III) ions (As3+) in aqueous solutions using anodic stripping voltammetry. CoAu/rGO was thoroughly tested in the presence of As3+ in a neutral medium (bicarbonate buffer, pH = 7), and the limit of detection was found to be as low as 1.51 ppb, significantly lower than the maximum permissible value set by the World Health Organization at 10 ppb. Its possible sensor application was confirmed by the preserved response to As3+ ions in samples simultaneously containing interferents such as Cu2+ ions. The real-life application of this material was validated by the determination of As3+ ions in real samples from the city water supply system (the city of Zrenjanin in Vojvodina) and rivers (the Begej River, the Drina River and the Danube River). Besides the high sensitivity of CoAu/rGO towards As3+ ions, its stability was also monitored over a certain time, demonstrating that it can be used with great precision in sensors for routine water analysis over extended periods. Overall, this study offers a green, highly stable, accurate and precise electrochemical platform for arsenic detection that requires reagent-free sample preparation
Electro-activated Persulfate Oxidation of Biodiesel Wastewater Following Acidification Phase: Optimization of Process Parameters Using Box–Behnken Design
No full text© 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG part of Springer Nature.High volumes of wastewater with high pollutant concentration form in the transesterification stage of the process applied for biodiesel production from waste vegetable oils. In this study, application of the advanced electrocoagulation process following acidification was investigated in the biodiesel wastewater treatment. Through the acidification step of the sequential process, respectively, 25.4%, 68.7%, and 50.0% removal efficiencies for COD, oil-grease, and volatile fatty acids (VFAs) were obtained. Electro-activated persulfate (EAP) oxidation was modeled and optimized by using the response surface methodology and Box–Behnken design. The effect of independent variables (current, persulfate/COD ratio, time) on COD, oil-grease, VFAs removal, and total cost and the interaction of the variables of the process were determined. The maximum oil-grease removal efficiency predicted by using the model was 98.3% under the optimum conditions (current: 4 A, persulfate/COD: 4.4, and time: 15 min), whereas oil-grease removal efficiency obtained by the verification experiments performed at optimum conditions was found to be 97.2%. Sequential acidification–EAP process is an appropriate treatment method for biodiesel wastewater with high oil-grease concentration, and response surface methodology is a powerful tool for optimizing the operational conditions of EAP oxidation for COD, oil-grease, VFAs removal, and total cost. Graphical abstract: [Figure not available: see fulltext.]
Production Sericin/Poly(Vinyl Alcohol) Blend Membranes Containing One-Step Synthesized Silver Nanoparticles by UV Radiation for Obtaining Versatile Antibacterial Materials
No full textIn this study, silver nanoparticles (AgNPs) were in-situ synthesized in silk sericin/poly(vinyl alcohol) (SS/PVA) mixtures by an easy one-step synthesis method with the presence of ultraviolet (UV) radiation. Then, the SS/PVA composite membranes containing AgNPs were obtained by solvent casting method. The chemical structures of the membranes were investigated by fourier-transform infrared spectroscopy (FTIR) and results showed that the membranes were a mixture of silk sericin and PVA. The morphological features of the membranes were investigated by field emission scanning electron microscopy (FE-SEM) and it was seen that AgNPs containing membranes have heterogeneous structures. Energy dispersive spectroscopy (EDS) analysis revealed that the membranes contain carbon, oxygen, nitrogen, sulfur and silver. X-ray diffractometer (XRD) and thermogravimetric (TGA) analyses also proved the presence of AgNPs in the structure of membranes. The antibacterial activities of membranes containing AgNPs were investigated on Staphylococcus aureus and Escherichia coli bacteria with disk diffusion test and liquid culture medium incubation. It was found that SS/PVA membranes containing 5 and 10 mM AgNPs have quite high antibacterial activity on both types of bacteria. The functional SS/PVA membranes have capacity to be used in biomedical applications such as wound care materials. In this work, silver nanoparticles (AgNPs) are synthesized in-situ with UV light within silk sericin/poly(vinyl alcohol) (SS/PVA) polymer mixture and SS/PVA membranes containing AgNPs are obtained with solvent casting method. Various physical, chemical and morphological properties of membranes are examined. The antibacterial activity of the membranes is investigated on bacteria, and the membranes show high antibacterial activity. imageScientific and Technological Research Council of Turkiye (TUBITAK) [1919B012202436, 2209-A]The author would like to thank Scientific and Technological Research Council of Turkiye (TUBITAK) for their financial support to this work under the project 1919B012202436 (2209-A) number
