28 research outputs found
Low temperature synthesis of multiwalled carbon nanotubes and incorporation into an organic solar cell
Abstract: Metal nanoparticle (MNP) catalysts used for the synthesis of multiwalled carbon nanotubes (MWCNTs) consisted of single metals (Fe, Ni or Co) and bimetallic mixture (CoFe, NiFe or NiCo). MWCNTs were successfully synthesised at 200 _C in 10 min using liquefied petroleum gas as carbon source with non-equilibrium plasma enhanced chemical vapour deposition (PECVD) method. The nanostructures and the morphology of the MNPs and the MWCNTs film were characterised using relevant microscopic and spectroscopic methods. The synthesised MWCNTs were used as part of the electrode material in organic solar cell (OSC) set-up. Poly (3,4- ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS) was used as an electron transporter and poly-3-hexyl thiophene (P3HT) as an electron donor. The performance of OSC devices was tested using standard electrical measurements and solar simulator operating at 100 mW/cm2. The measured power conversion efficiencies was found to be dependent on the metal catalyst used during synthesis. Among all the catalysts employed in this investigation, the best device performance was found from the synthesis of MWCNTs using Fe as a catalyst followed by Co and then Ni, respectively
Design of multi-layer graphene membrane with descending pore size for 100% water desalination by simulation using ReaxFF
DATA AVAILABILITY STATMENT : Data are available upon request from the corresponding author and
based on university rules.The performance of a desalination membrane depends on a specific pore size suitable for
both water permeability and salt rejection. To increase membrane permeability, the applied pressure
should be increased, which creates the need to improve membrane stability. In this research article,
a molecular dynamics (MD) simulation was performed using ReaxFF module from Amsterdam
Modeling suite (AMS) software to simulate water desalination efficiency using a single and multi-layer
graphene membrane. The graphene membrane with different pore sizes and a multi-layer graphene
membrane with descending pore size in each layer were designed and studied under different
pressures. The stability of the membrane was checked using Material Studio 2019 by studying the
dynamics summary. The single-layer graphene membrane was evaluated under pressures ranging
from 100 to 500 MPa, with the salt rejection ranging from 95% to 82% with a water permeability of
0.347 109 to 2.94 109 (mm.g.cm2s1.bar1), respectively. Almost 100% salt rejection was
achieved for the multi-layer graphene membrane. This study successfully demonstrated the design
and optimization of graphene membrane performance without functionalization.The Faculty of Sciences at the University of Johannesburg, South Africa,https://www.mdpi.com/journal/membranesam2023Chemistr
Guiding water into carbon nanopipes with the aid of bipolar electrochemistry
Microfluidics and Nanofluidics, 1(3): pp. 284-288. Retrieved September 19, 2006 from http://nano.materials.drexel.edu/publications.html.The targeted bipolar electrodeposition of
polypyrrole was carried out onto the tips of hydrophilic
carbon nanopipes. By aligning an external electric field
relative to the nanopipes, the deposition of polypyrrole
onto selected ends could be achieved without physically
contacting the nanopipes. After deposition, carbon
nanopipes with both partially open and fully blocked tips
were found. Experiments conducted in an environmental
scanning electron microscope showed that water enters
the nanopipes through the tip with polypyrrole due to the
higher hydrophilicity of the polymer compared to the
tube walls. As a result, it was possible to guide the entry
of water from a specific end of the tube and fill the tube
from the selected side. Condensation experiments conducted
on nanopipes with polypyrrole on both tips shows
the difference in hydrophilicity of the nanopipes compared
to the polypyrrole. The ability to selectively control
the site of condensation and uptake of fluid by
carbon nanotubes or nanopipes is very important for the
development of nanotube-based nanofluidic devices
Effect of inclusion of MOF-polymer composite onto a carbon foam material for hydrogen storage application
Despite the extensive studies done on the remarkable characteristics of metal–organic frameworks (MOFs) for gas storage applications, several issues still preclude their widespread commercial lightweight applications. In most cases, MOF materials are produced in powdery form and often require shaping to attain application-specific properties. Fabrication of MOF-polymer composites is considered an attractive approach for shaping MOF powders. In most cases, the final hybrid material retains the intrinsic adsorbing properties of the pristine MOF coupled with other interesting synergistic features which are sometimes superior to their pristine counterparts. In this regard, the use of porous polymers of intrinsic microporosity (such as PIM-1) has proved to be of interest. However, most of these polymers lack some other important properties such as conductivity, which is of paramount importance in a hydrogen storage system. It is on this basis that our study aimed at direct anchoring of a PIM-1/MOF viscous solution onto a carbon foam (CF) substrate. The effects of PIM-1/UiO-66(Zr) inclusion into CF to the resulting thermal properties (thermal conductivity, thermal diffusivity and volumetric heat capacity) as well as hydrogen uptake capacity was investigated. Contrary to our expectations, the incorporation of PIM-1/UiO-66(Zr) into CF only offered better handling but did not lead to the enhancement of thermal conductivity.The Department of Science and Innovation (DSI) of South Africa towards HySA Infrastructure, National Research Foundation (NRF) for SA/France collaboration funding and the Royal Society—DFID Africa Capacity Building Initiative Programme Grant.http://link.springer.com/journal/109042021-08-09hj2020Chemistr
Polymer-based shaping strategy for zeolite templated carbons (ZTC) and their metal organic framework (MOF) composites for improved hydrogen storage properties
Porous materials such as metal organic frameworks (MOFs), zeolite templated carbons
(ZTC), and some porous polymers have endeared the research community for their
attractiveness for hydrogen (H2) storage applications. This is due to their remarkable
properties, which among others include high surface areas, high porosity, tunability,
high thermal, and chemical stability. However, despite their extraordinary properties,
their lack of processability due to their inherent powdery nature presents a constraining
factor for their full potential for applications in hydrogen storage systems. Additionally,
the poor thermal conductivity in some of these materials also contributes to the
limitations for their use in this type of application. Therefore, there is a need to develop
strategies for producing functional porous composites that are easy-to-handle and with
enhanced heat transfer properties while still retaining their high hydrogen adsorption
capacities. Herein, we present a simple shaping approach for ZTCs and their MOFs
composite using a polymer of intrinsic microporosity (PIM-1). The intrinsic characteristics
of the individual porous materials are transferred to the resulting composites leading
to improved processability without adversely altering their porous nature. The surface
area and hydrogen uptake capacity for the obtained shaped composites were found
to be within the range of 1,054–2,433 m2g−1 and 1.22–1.87 H2 wt. %, respectively at
1 bar and 77 K. In summary, the synergistic performance of the obtained materials is
comparative to their powder counterparts with additional complementing properties.The Department
of Science and Technology (DST) of South Africa toward
HySA Infrastructure (Grant No. ENMH01X), National Research
Foundation (NRF) for SA/France collaboration funding (Grant
No. ENMH20X) and the Royal Society—DFID Africa Capacity
Building Initiative Programme Grant (Grant No. AQ150029).http://www.frontiersin.org/Chemistryam2020Chemistr
Hall Measurements on Carbon Nanotube Paper Modified With Electroless Deposited Platinum
Carbon nanotube paper, sometimes referred to as bucky paper, is a random arrangement of carbon nanotubes meshed into a single robust structure, which can be manipulated with relative ease. Multi-walled carbon nanotubes were used to make the nanotube paper, and were subsequently modified with platinum using an electroless deposition method based on substrate enhanced electroless deposition. This involves the use of a sacrificial metal substrate that undergoes electro-dissolution while the platinum metal deposits out of solution onto the nanotube paper via a galvanic displacement reaction. The samples were characterized using SEM/EDS, and Hall-effect measurements. The SEM/EDS analysis clearly revealed deposits of platinum (Pt) distributed over the nanotube paper surface, and the qualitative elemental analysis revealed co-deposition of other elements from the metal substrates used. When stainless steel was used as sacrificial metal a large degree of Pt contamination with various other metals was observed. Whereas when pure sacrificial metals were used bimetallic Pt clusters resulted. The co-deposition of a bimetallic system upon carbon nanotubes was a function of the metal type and the time of exposure. Hall-effect measurements revealed some interesting fluctuations in sheet carrier density and the dominant carrier switched from N- to P-type when Pt was deposited onto the nanotube paper. Perspectives on the use of the nanotube paper as a replacement to traditional carbon cloth in water electrolysis systems are also discussed
Comprehensive transcriptome of the maize stalk borer, Busseola fusca, from multiple tissue types, developmental stages, and parasitoid wasp exposures
International audienc
Synthesis of Carbon Nanomaterials from Biomass Utilizing Ionic Liquids for Potential Application in Solar Energy Conversion and Storage
Considering its availability, renewable character and abundance in nature, this review assesses the opportunity of the application of biomass as a precursor for the production of carbon-based nanostructured materials (CNMs). CNMs are exceptionally shaped nanomaterials that possess distinctive properties, with far-reaching applicability in a number of areas, including the fabrication of sustainable and efficient energy harnessing, conversion and storage devices. This review describes CNM synthesis, properties and modification, focusing on reports using biomass as starting material. Since biomass comprises 60–90% cellulose, the current review takes into account the properties of cellulose. Noting that highly crystalline cellulose poses a difficulty in dissolution, ionic liquids (ILs) are proposed as the solvent system to dissolve the cellulose-containing biomass in generating precursors for the synthesis of CNMs. Preliminary results with cellulose and sugarcane bagasse indicate that ILs can not only be used to make the biomass available in a liquefied form as required for the floating catalyst CVD technique but also to control the heteroatom content and composition in situ for the heteroatom doping of the materials