The Effect Of Metal Loading On The Performance Of Tri-Metallic Supported Catalyst For Carbon Nanotubes Synthesis From Liquefied Petroleum Gas

Carbon nanotubes (CNT) were synthesized from liquefied petroleum gas by a chemical vapor deposition method using a Fe-Co-Mo/MgO supported catalyst. Metal loading was varied from 2.5 to 20 wt%. The catalyst with metal loading of 10 wt% produced the highest CNT yield, at 4.55 g CNT/g catalyst. This high CNT yield was attributed to the high pore volume of the catalyst. The diameter of the CNT was quite variable: the outer diameter ranged from about 4 to 12 nm, while the inner diameter ranged from about 2 to 5 nm. The catalyst with 10 wt% metal loading produced CNT with the highest surface area and the largest total pore volume. XRD analysis detected the existence of highly oriented pyrolytic graphite, C(002), at 2 theta ≈ 26o, which was attributed to the CNT

On the mechanism of carbon nanotube formation by means of catalytic chemical vapour deposition

Despite enormous strides in the synthesis of carbon nanotubes (CNTs), the mechanism for growth is still a highly debated issue. It is generally accepted that the model for carbon filament growth [1, 2], derived from concepts of vapour-liquid-solid theory, also applies to CNT growth. However, this model fails to account for the growth of CNTs from noble metal [3{7], ceramic [8, 9] and semiconducting nanoparticles [10{13], all of which are regarded as unable to catalyse the dissociation of hydrocarbons. In addition, in their bulk form, these materials do not have a catalytic function to produce graphite. This work examines non-traditional catalyst assisted chemical vapour deposition of CNTs with a view to determine the essential role of the catalyst in nanotube growth. CNT synthesis based upon noble metal and two approaches using germanium nanoparticles are presented. Extensive characterisation has been undertaken of each step of the growth process, and the synthesized carbon nanotubes are analysed by atomic force microscopy, electron microscopy and Raman spectroscopy. The results indicate that good densities of high quality single-walled carbon nanotubes are produced by these techniques. Additionally, the effects of different catalyst support interactions were explored by testing combinations of metal catalysts and support media. This study showed that the support has a strong effect on the chemical activity and morphology of the catalyst. The results presented show that the commonly utilised model of carbon filament growth is inadequate to describe CNT growth from non-traditional catalysts. A model for CNT growth consistent with the experimental results is proposed, in which the structural reorganisation of carbon to form CNTs is paramoun

Progress and Recent Trends in the Application of Nanoparticles as Low Carbon Fuel Additives—A State of the Art Review

The first part of the current review highlights the evolutionary nuances and research hotspots in the field of nanoparticles in low carbon fuels. Our findings reveal that contribution to the field is largely driven by researchers from Asia, mainly India. Of the three biofuels under review, biodiesel seems to be well studied and developed, whereas studies regarding vegetable oils and alcohols remain relatively scarce. The second part also reviews the application of nanoparticles in biodiesel/vegetable oil/alcohol-based fuels holistically, emphasizing fuel properties and engine characteristics. The current review reveals that the overall characteristics of the low carbon fuel–diesel blends improve under the influence of nanoparticles during combustion in diesel engines. The most important aspect of nanoparticles is that they act as an oxygen buffer that provides additional oxygen molecules in the combustion chamber, promoting complete combustion and lowering unburnt emissions. Moreover, the nanoparticles used for these purposes exhibit excellent catalytic behaviour as a result of their high surface area-to-volume ratio—this leads to a reduction in exhaust pollutants and ensures an efficient and complete combustion. Beyond energy-based indicators, the exergy, economic, environmental, and sustainability aspects of the blends in diesel engines are discussed. It is observed that the performance of the diesel engine fuelled with low carbon fuels according to the second law of efficiency improves under the influence of the nano-additives. Our final part shows that despite the benefits of nanoparticles, humans and animals are under serious threats from the highly toxic nature of nanoparticles. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.20JCJQJC00160; Cardiff University; Universiti Tenaga Nasional: IC6-BOLDREFRESH2025This research was funded by Tianjin Science Fund for Distinguished Young Scholars, grant number 20JCJQJC00160, and the Universiti Tenaga Nasional grant no. IC6-BOLDREFRESH2025 (HCR) under the BOLD2025 Program. The APC was funded by Cardiff University

New materials, regimes and applications of fibre laser technology

Nonlinear optics enables the manipulation of spectral and temporal characteristics of optical pulses interacting with a dielectric medium. Optical fibres, as a uniquely practical medium, provide an environment for effectively exploiting the nonlinear effects. This has facilitated the rapid growing interest in this field focused on the investigation of fibrebased sources incorporated with various novel saturable absorber devices for ultrashort pulse generation. This thesis reports a series of experiments exploring the ongoing research in the field of nonlinear optics, including the development of ultrafast mode-locked fibre sources and their applications in supercontinumm generation and third order parametric interactions in new carbon materials. Firstly, the integration of carbon-based materials with rare-earth doped media allows the demonstration of ultrafast mode-locked laser sources operating at wavelengths across the near-infrared region in a compact, low cost and environmentally robust scheme. Power scaling of such sources can be achieved by operating in the all-normal dispersion regime making use of a glass-substrate saturable absorber device that exhibits a higher damage threshold. Supercontinuum generation has been used as an effective method for spectral broadening. Pumping with a conceptually simple and reliable fibre-based system, a continuum covering from 2 to 3 μm is generated in a highly nonlinear GeO2 fibre. This experiment demonstrates a robust and long-term stable source of radiation in an important band, coincident with a portion of the atmospheric transmission window. Finally, the demonstration of a simple and compact nano-material based dual-wavelength system shows the performance of such devices as a simultaneous saturable absorber and passive synchroniser. An experimental study of coherent frequency mixing at large frequency shifts in a graphene sample, pumped by a two-colour fibre-integrated source, proves the strong nonlinear response of this new carbon material.Open Acces

Enhancement of transition metal-based supercapacitor materials for improved performance

In this research work, metal-doped MoS2 of Cobalt and Manganese (Co-MoS2 and Mn-MoS2) nanocomposites of different ratios of dopant concentrations were synthesized with a facile hydrothermal technique. The samples were characterized using various instruments to elucidate the properties and novelties of the prepared nanomaterials and likewise to establish their supercapacitive suitability for energy storage devices. The bibliometric evaluation of the development of literary works involving supercapacitor devices since the use of MoS2 as the active materials in energy storage (Supercapacitor) was performed. The bibliometric analysis of the studied materials gives us perspectives on the strengths and weaknesses of the materials, which enable us to identify the area of focus and the targeted publication outlets. The Co-MoS2 electrode materials (CMS1 and CMS3) were electrochemically evaluated for their energy storage performance, the materials exhibit specific capacitances of 164 and 146 Fg-1 at 1 Ag-1 for the working electrodes, respectively. Also, the energy densities of 3.67 and 2.05 Wh/kg with power densities of 3279.97 and 2960.26 W/kg were calculated for both electrode materials, respectively. While the electrochemical performance of the Mn-doped MoS2 electrode material showed a pseudo-capacitive behavior, with a specific capacitance of 70.37 Fg−1, and with a corresponding energy density of 3.14 Whkg−1 and a power density of 4346.35 Wkg−1. The general obtained results show that the electrode materials were well prepared and the enhancement of MoS2 properties is achievable with the transition metal composites. These improved properties of MoS2 composites showing the suitability of the nanomaterials for the energy storage applications have been explained in this work with possible future works recommended in the report.PhysicsD. Phil. (Physics

Capabilities and governance of nanotechnology in the developing world : insights from India

Based on half a decade of interdisciplinary research and informed by multi-stakeholder insights, this book proposes options for effective and inclusive governance for nanotechnology in India. It covers a range of issues such as potential research and development (R&D) prospects, science and technology (S&T) capacities and innovation systems, issues of environment, health and safety, risk and regulatory preparedness, and prospective socio-economic and ethical repercussions. With a focus on Indian developments, as well as the accompanying regulatory challenges, the book provides insights for policy and effective multi-level governance of nanotechnology

A review of monitoring methods for triclosan and its occurrence in aquatic environments

Triclosan is a phenyl ether with broad spectrum antimicrobial action which is employed in a great number of everyday household and personal care products including plastics, fabrics, soaps, deodorants, toothpaste, and cosmetics. There is serious concern, however, regarding this widespread use in terms of the potential environmental impacts of triclosan. Triclosan may enter the aquatic environment via numerous pathways including discharge of effluents from industries and wastewater treatment plants. To date, however, a comprehensive review of the determination of triclosan in aquatic environments has been not reported. Herein, we review the environmental concentration of triclosan in aquatic systems globally, as well as its stability and toxicity. The wide variety of monitoring methods utilized for the determination of triclosan are discussed, including those based on chromatography-mass spectrometry, electrochemistry, capillary zone electrophoresis and spectrophotometry over the last 10 years.The University of Pretoria, the Water Research Commission (grant K5-2438), the Photonics Initiative of South Africa (grant PISA-15-DIR-06) and the National Research Foundation of South Africa (grants 90720 and 93394).http://www.journals.elsevier.com/trends-in-analytical-chemistry2017-12-31hb2017Chemistr

Towards a sustainable PV waste policy: Exploring the management practices of end-of-life solar photovoltaic modules in Australia

Solar photovoltaic (PV) systems are effective measures to reduce the greenhouse gas emissions. However, the large exploitation of solar PV modules, leads to undesirable waste accumulation, affecting the environment. Solar PV waste management research is an emerging field that has received more attention recently, affected by the increase volume of solar PV disposals. However, only a few studies have examined the current practices in solar photovoltaic waste management. In Australia, because of social and economic factors (such as the replacement of small-scale PV systems come with new rebates), residential solar systems are decommissioned earlier than expected before reaching their end-of-life (EoL). 70% of the market share of PV systems are predominately dominated by the residential market in Australia as of 2020. The average practical lifetime of PV modules instead of 20-30 years is 15-20 years in Australia. Therefore, the volume of EoL PV from the residential sector entering the waste stream in the coming decade will be higher than previously predicted. This study aims to assess the environmental impacts of waste from rooftop solar photovoltaic panels in Australia to inform sustainable policies. To achieve the aim of the research, the following objectives are investigated: 1) exploring the current practices of managing end-oflife rooftop solar photovoltaic panels in Australia; 2) developing an optimised system approach in dealing with solar photovoltaic waste in Australia; and 3) assessing the environmental impacts of end-of-life rooftop solar photovoltaic panels in Australia within the developed assessment framework. To achieve the research objectives, several methods are adopted to analyse the primary and secondary data for this research. A modified Fuzzy Delphi Method (FDM) is adopted in gathering data through interviews and questionnaires from experts in the field. The results show that, crystalline silicon panels were the most common panels on the Australian market and the ones that are being installed frequently. On policies, although the Australian government has banned PV waste from going to landfill since 2014, there were no regulations or action plans to manage PV waste. The absence of policies and regulations results in unregulated movement and tracking of solar PV waste in and out of Australia as well as within and across the states. The extent of the PV recovery and recycling warrants further investigation. Moreover, infrastructure and logistics has been a significant problem because of the geographical spread of the country and how it affects transportation and the supply chain. Findings led to the establishment of a conceptual framework for the current treatment of solar PV waste in Australia. Furthermore, a Weibull distribution model is employed to forecast the PV waste in the next three decades in South Australia. The study further estimates the pollutant emission associated with the collection and transportation of the waste for recycling and recovery. Results indicate that, there will be 109,007 tons of PV waste generated in urban and suburban context in South Australia by 2050. Among the three routing scenarios generated, the third scenario with optimised transfer stations and an additional recycling facility showed more than 34% reduction in pollutant emission. This study evaluates the environmental impacts of three policy options for mono and multi crystalline silicon (c-Si) solar panel waste modules. The impact of transport distance from transfer stations to the recycling centre is also assessed. The life cycle assessment revealed that, -1E+06 kgCO2eq and -2E+06 kgCO2eq are associated with the mandatory product stewardship scenarios under global warming potential for mono and multi c-Si solar modules respectively. However, the non-existence of a product stewardship will produce a global warming impact of 1E+05 kgCO2eq for both modules. The global warming effects revealed that, collecting and recycling most of the multi c-Si panels were not effective (-365 kg CO2-eq, -698.4 kg CO2-eq, -1032 kg CO2-eq) compared to keeping them away from the landfills and fully recycling (- 2E+06 kg CO2-eq) them. It was also highlighted that, the highest environmental impact regarding the transport distances was the scenario of one recycling centre serving over 107 transfer stations with a global warming potential of 1E+06 kgCO2eq. In conclusion, this study contributes to the management of the supply market of solar PV technologies, using Australia as a case study. The recommendations derived from the study include: creating collection centres for EoL PV modules in South Australia, developing a logistic network to for the collection of EoL PV modules, creating and enhancing the PV recycling market for recovered materials, issuing a regulatory landfill ban for EoL solar PV module in South Australia, developing a mandatory product stewardship for PV waste in Australia, promoting and providing financial incentives to current and future infrastructure for PV recycling, minimising the exportation of PV waste overseas and interstate, encouraging industry led research on new innovations to improve the recovery of different PV technology families, developing sustainable measures to cut emissions for recycling through research and development in South Australia, and building the capacity and promoting awareness on the benefits of PV recycling in South Australia.Thesis (Ph.D.) -- University of Adelaide, School of Architecture and Civil Engineering, 202