| 1. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Backes, Claudia, et al.
(författare)
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Production and processing of graphene and related materials
- 2020
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Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a 'hands-on' approach, providing practical details and procedures as derived from literature as well as from the authors' experience, in order to enable the reader to reproduce the results. Section I is devoted to 'bottom up' approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section II covers 'top down' techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers' and modified Hummers' methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by employing a theoretical data-mining approach. The exfoliation of LMs usually results in a heterogeneous dispersion of flakes with different lateral size and thickness. This is a critical bottleneck for applications, and hinders the full exploitation of GRMs produced by solution processing. The establishment of procedures to control the morphological properties of exfoliated GRMs, which also need to be industrially scalable, is one of the key needs. Section III deals with the processing of flakes. (Ultra)centrifugation techniques have thus far been the most investigated to sort GRMs following ultrasonication, shear mixing, ball milling, microfluidization, and wet-jet milling. It allows sorting by size and thickness. Inks formulated from GRM dispersions can be printed using a number of processes, from inkjet to screen printing. Each technique has specific rheological requirements, as well as geometrical constraints. The solvent choice is critical, not only for the GRM stability, but also in terms of optimizing printing on different substrates, such as glass, Si, plastic, paper, etc, all with different surface energies. Chemical modifications of such substrates is also a key step. Sections IV-VII are devoted to the growth of GRMs on various substrates and their processing after growth to place them on the surface of choice for specific applications. The substrate for graphene growth is a key determinant of the nature and quality of the resultant film. The lattice mismatch between graphene and substrate influences the resulting crystallinity. Growth on insulators, such as SiO2, typically results in films with small crystallites, whereas growth on the close-packed surfaces of metals yields highly crystalline films. Section IV outlines the growth of graphene on SiC substrates. This satisfies the requirements for electronic applications, with well-defined graphene-substrate interface, low trapped impurities and no need for transfer. It also allows graphene structures and devices to be measured directly on the growth substrate. The flatness of the substrate results in graphene with minimal strain and ripples on large areas, allowing spectroscopies and surface science to be performed. We also discuss the surface engineering by intercalation of the resulting graphene, its integration with Si-wafers and the production of nanostructures with the desired shape, with no need for patterning. Section V deals with chemical vapour deposition (CVD) onto various transition metals and on insulators. Growth on Ni results in graphitized polycrystalline films. While the thickness of these films can be optimized by controlling the deposition parameters, such as the type of hydrocarbon precursor and temperature, it is difficult to attain single layer graphene (SLG) across large areas, owing to the simultaneous nucleation/growth and solution/precipitation mechanisms. The differing characteristics of polycrystalline Ni films facilitate the growth of graphitic layers at different rates, resulting in regions with differing numbers of graphitic layers. High-quality films can be grown on Cu. Cu is available in a variety of shapes and forms, such as foils, bulks, foams, thin films on other materials and powders, making it attractive for industrial production of large area graphene films. The push to use CVD graphene in applications has also triggered a research line for the direct growth on insulators. The quality of the resulting films is lower than possible to date on metals, but enough, in terms of transmittance and resistivity, for many applications as described in section V. Transfer technologies are the focus of section VI. CVD synthesis of graphene on metals and bottom up molecular approaches require SLG to be transferred to the final target substrates. To have technological impact, the advances in production of high-quality large-area CVD graphene must be commensurate with those on transfer and placement on the final substrates. This is a prerequisite for most applications, such as touch panels, anticorrosion coatings, transparent electrodes and gas sensors etc. New strategies have improved the transferred graphene quality, making CVD graphene a feasible option for CMOS foundries. Methods based on complete etching of the metal substrate in suitable etchants, typically iron chloride, ammonium persulfate, or hydrogen chloride although reliable, are time- and resource-consuming, with damage to graphene and production of metal and etchant residues. Electrochemical delamination in a low-concentration aqueous solution is an alternative. In this case metallic substrates can be reused. Dry transfer is less detrimental for the SLG quality, enabling a deterministic transfer. There is a large range of layered materials (LMs) beyond graphite. Only few of them have been already exfoliated and fully characterized. Section VII deals with the growth of some of these materials. Amongst them, h-BN, transition metal tri- and di-chalcogenides are of paramount importance. The growth of h-BN is at present considered essential for the development of graphene in (opto) electronic applications, as h-BN is ideal as capping layer or substrate. The interesting optical and electronic properties of TMDs also require the development of scalable methods for their production. Large scale growth using chemical/physical vapour deposition or thermal assisted conversion has been thus far limited to a small set, such as h-BN or some TMDs. Heterostructures could also be directly grown. Section VIII discusses advances in GRM functionalization. A broad range of organic molecules can be anchored to the sp(2) basal plane by reductive functionalization. Negatively charged graphene can be prepared in liquid phase (e.g. via intercalation chemistry or electrochemically) and can react with electrophiles. This can be achieved both in dispersion or on substrate. The functional groups of GO can be further derivatized. Graphene can also be noncovalently functionalized, in particular with polycyclic aromatic hydrocarbons that assemble on the sp(2) carbon network by pi-pi stacking. In the liquid phase, this can enhance the colloidal stability of SLG/FLG. Approaches to achieve noncovalent on-substrate functionalization are also discussed, which can chemically dope graphene. Research efforts to derivatize CNMs are also summarized, as well as novel routes to selectively address defect sites. In dispersion, edges are the most dominant defects and can be covalently modified. This enhances colloidal stability without modifying the graphene basal plane. Basal plane point defects can also be modified, passivated and healed in ultra-high vacuum. The decoration of graphene with metal nanoparticles (NPs) has also received considerable attention, as it allows to exploit synergistic effects between NPs and graphene. Decoration can be either achieved chemically or in the gas phase. All LMs,
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| 3. |
- Carlsson, Fredrik, 1968, et al.
(författare)
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Conformity and the demand for environmental goods
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We test the hypothesis that people conform to certain social norms, i.e. that some individuals may be willing to pay a higher price premium for green products the more widespread green consumerism is in society. To investigate consumer preferences for environmentally friendly products, we conducted a choice experiment where the respondents were asked to choose among coffee products varying with respect to their share of ecological beans, share of fair trade beans, and price. Three treatments were used, differing only in the information given about the choices made by other consumers. More specifically, the respondents in the three subgroups were told that 10%, 50%, and 90% of all other consumers chose the alternative with 100% ecological beans. We find different responses to the treatments across individuals. In particular, we can only confirm our hypothesis of conformity for women, although men appear to have stronger preferences for ecological coffee than women.
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| 4. |
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| 5. |
- García, Jorge H., 1972, et al.
(författare)
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Carbon Taxes
- 2021
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Ingår i: Oxford Research Encyclopedia of Environmental Science. - : Oxford University Press.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Economists argue that carbon taxation (and more generally carbon pricing) is the single most powerful way to combat climate change. Since this is so controversial, we need to explain it better, and to be precise, the efficiency gains are largest when the costs of abatement are strongly heterogeneous. This is often—but not always—the case. When it is not, standards can fill much the same role. To internalize the climate externality, economic efficiency calls for a global carbon tax (or price) that is equal to the global damage or the so-called social cost of carbon. However, equity considerations as well as existing geographical and sectoral differences in the effectiveness of carbon taxation at reducing emissions, suggest earlier implementation of relatively high taxation levels in some sectors or countries—for instance, among richer economies followed by a more gradual phase-in among low-income countries. The number of national and subnational carbon pricing policies that have been implemented around the world during the first years following the Paris Agreement of 2015 is significant. By 2020, these programs covered 22% of global emissions with an average carbon price (weighted by the share of emissions covered) of USD15/tCO and a maximum price of USD120/tCO The share of emissions covered by carbon pricing as well as carbon prices themselves are expected to consistently rise throughout the decade 2021–2030 and beyond. Many experts agree that the social cost of carbon is in the range USD40–100/tCO . Anti-climate lobbying, public opposition, and lack of understanding of the instrument are among the key challenges faced by carbon taxation. Opportunities for further expansion of carbon taxation lie in increased climate awareness, the communicative resources governments have to help citizens understand the logic behind carbon taxation, and earmarking of carbon tax revenues to address issues that are important to the public such as fairness.
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| 6. |
- García, Jorge H., 1972, et al.
(författare)
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Corporate environmental management in transition economies: The case of Central and Eastern Europe
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We use firm-level data to study the adoption of Environmental Management Practices (EMPs) in the most polluting industrial sectors in Bulgaria, Hungary, Lithuania, Poland, Romania, and Slovakia during the 1990 – 1998 period when these countries were in a transition away from a centrally planned economy. Despite the stickiness of a long established managerial regime and the declines in industrial output during this period, around 42% of the firms in our sample adopted Environmental Plans (EPs) and/or established Environmental Departments (EDs). The analysis reveals that enforcement and public disclosure of the environmental performance of firms are the most important forces behind the implementation of both of these EMPs. Also, but to a lesser extent, export oriented firms and larger firms are prone to adoption. Finally, we use a methodology that clarifies some of the links between different EMPs not addressed in earlier studies. Notably, once a firm has decided to adopt (or not adopt) an ED, additional increases in enforcement do not to lead to EP implementation.
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| 7. |
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| 8. |
- García, Jorge H., 1972
(författare)
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Essays on Asymmetric Information and Environmental Regulation through Disclosure
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation delves into different aspects of a relatively new policy approach for industrial pollution control: the public dissemination of information by regulators regarding the environmental performance of firms. These schemes are sometimes referred to as regulation through disclosure or informational regulation. It is presumed that disclosure as an environmental regulation triggers and intensifies interactions between polluting firms and workers, community groups, consumers, and owners. It thus increases the costs of non-compliance with environmental law through channels that do not directly involve the regulator. The understanding that information is important for market emergence together with evidence suggesting that disclosure schemes can influence firms environmental performance at a relatively low regulatory cost, have resulted in a certain enthusiasm for these approaches. There are however still voids in the theoretical foundations of disclosure as regulation, as well as in the empirical evidence supporting its alleged effectiveness (in particular in developing and emerging economies). This dissertation aims at contributing to the growing literature on disclosure in both these regards. The discussion consists of four self-contained chapters. Chapter 1 looks into some theoretical issues of environmental compliance under asymmetric information. Chapters 2 and 3 constitute an empirical evaluation of a well-structured disclosure program, Indonesias PROPER, while Chapter 4 studies the more informal type of provision of information in Central and Eastern Europe. Informal mechanisms such as public disgrace faced by managers and owners of polluting firms and moral suasion have been suggested as possible explanatory factors of firm environmental behavior. The first contribution of this dissertation is in this area. Building on earlier work, Chapter 1 develops a model of social interactions where managers and owners of highly polluting firms face stigmatization and losses in reputation in society. I argue that symmetric information is a silent assumption of earlier papers on social interactions that is not necessarily met in the industrial pollution case. I study situations where firms environmental performance is perfectly observable and imperfectly observable. The findings show that relaxing the perfect observability assumption, even by a small a margin, could have profound effects on the reputation functions in such a way that high levels of compliance cannot be sustained in equilibrium. Chapters 2 and 3 evaluate the effectiveness of Indonesias public disclosure program PROPER. The main result is that the policy was responsible for a rapid and significant reduction in emissions intensity as measured by biochemical oxygen demand, BOD, and chemical oxygen demand, COD (the characteristics of those firms that were most responsive to the program are also unveiled). Chapter 4 is also an empirical study of more informal type of provision of information in Central and Eastern Europe during the first years of transition. The analysis reveals that enforcement and public disclosure of the environmental performance of firms are the most important forces behind the implementation of Environmental Management Practices. The findings of Chapters 2, 3 and 4 strengthen the belief that thin markets and other sluggish mechanisms are the results of imperfect information and also indicate that informational regulation is a promising strategy to tackle industrial pollution in the presence of weak institutions.
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| 9. |
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| 10. |
- García, Jorge H., 1972, et al.
(författare)
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Public Disclosure of Industrial Pollution: The PROPER Approach for Indonesia?
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper evaluates the effectiveness of the Program for Pollution Control Evaluation and Rating (PROPER) in Indonesia. PROPER, the first major public disclosure program in the developing world, was launched in June 1995; though it collapsed in 1998 with the Asian financial crisis, it is currently being revived. There have been claims of success for this pioneering scheme, yet little formal analysis has been undertaken. We analyze changes in emissions concentrations (mg/L) using panel data techniques with plant-level data for participating firms and a control group. The results show that there was indeed a positive response to PROPER, especially among firms with poor environmental compliance records. The response was immediate, and firms pursued further emissions reductions in the following months. The total estimated reductions in biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were approximately 32%.
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