4,097,079 research outputs found
Solar spectrum photocatalytic conversion of CO2 to CH4 utilizing TiO2 nanotube arrays embedded with graphene quantum dots
No full textTiO2 nanotube arrays (TNT) offer an exciting prospect as a photocatalytic material architecture due to the combined properties of high surface area, 1-D vectorial charge transfer, and reduced photogenerated charge recombination. However the TiO2 band gap (≈3.2eV) limits light absorption to the UV region, which comprises but a small fraction of the solar spectrum energy. Graphene is known to effectively absorb visible light, and due to its high conductivity promote efficient charge transfer. Herein, we present a novel photocatalyst composed of TNTs sensitized with electrodeposited graphene quantum dots (GQDs). GQDs electrodeposition-duration is varied to optimize photocatalytic performance of the resulting nanostructured graphene-TNT (G-TNT) films. Under solar spectrum illumination we find optimal G-TNT samples promote a CO2 to CH4 photocatalytic conversion rate of 1.98ppmcm-2 h-1, with carbon origin confirmed by 13CO2 isotopic test. © 2018 Elsevier Ltd. All rights reserved.1
Recent Advances in Quantum Dots for Photocatalytic CO2 Reduction: A Mini-Review
No full textSolar energy–driven carbon dioxide (CO2) reduction to valuable solar fuels/chemicals (e.g., methane, ethanol, and carbon monoxide) using particulate photocatalysts is regarded as one of the promising and effective approaches to deal with energy scarcity and global warming. The growth of nanotechnology plays an eminent role in improving CO2 reduction (CO2R) efficiencies by means of offering opportunities to tailor the morphology of photocatalysts at a nanoscale regime to achieve enhanced surface reactivity, solar light absorption, and charge separation, which are decisive factors for high CO2R efficiency. Notably, quantum dots (QDs), tiny pieces of semiconductors with sizes below 20 nm, offering a myriad of advantages including maximum surface atoms, very short charge migration lengths, size-dependent energy band positions, multiple exciton generation effect, and unique optical properties, have recently become a rising star in the CO2R application. In this review, we briefly summarized the progress so far achieved in QD-assisted CO2 photoreduction, highlighting the advantages of QDs prepared with diverse chemical compositions such as metal oxides, metal chalcogenides, carbon, metal halide perovskites, and MXenes. © Copyright © 2021 Park, Murali, Modigunta, In and In.1
Measuring the Effects of the Uniform Settlement Rate Requirement in the International Telephone Industry
No full textAs a case study of an ex-post evaluation of regulations, in this paper I evaluate the uniform settlement rate requirement, a regulation that was introduced in 1986 and that was applied to the international telephone market in the U.S. for more than 20 years. In a bilateral market between the U.S. and a foreign country, each U.S. firm and its foreign partner jointly provide international telephone service in both directions, compensating each other for terminating incoming calls to their respective countries. The per-minute compensation amount for providing the termination service, referred to as the settlement rate, is determined by a bargaining process involving the two firms. In principle, each U.S. firm could have a different settlement rate for the same foreign country. In 1986, however, the Federal Communications Commission introduced the Uniform Settlement Rate Requirement (USRR), which required all U.S. firms to pay the same settlement rate to a given foreign country. The USRR significantly affected the relative bargaining positions of the U.S. and foreign firms, thereby changing negotiated settlement rates. This paper identifies two main routes through which the settlement rates are changed by the implementation of the USRR: the Competition-Induced-Incentive Effect and the Most-Favored-Nation Effect. I then empirically evaluate the USRR by estimating a bargaining model and conducting counterfactual experiments aimed at measuring the size of the two effects of the USRR. The experiments show remarkably large impacts due to the USRR. Requiring a uniform settlement rate, for instance, results in an average 32.2 percent increase in the negotiated settlement rates and an overall 13.7 percent ($3.43 billion) decrease in the total surplus in the U.S. These results provide very strong evidence against the implementation of the USRR in the 1990s and early 2000s
A Welfare Analysis on Introducing Multi-Mode Service in Korea
No full textTo conduct a welfare analysis on the introduction of Multi-Mode Service (MMS) in Korea, the article estimates demand equations for pay TV services and calculates the conversion rates of pay TV subscribers to terrestrial TV due to the MMS. Then a welfare analysis is performed. The analysis shows that the net present value of the MMS is less than 0 regardless of various models and scenarios, indicating that the introduction of MMS is economically infeasible in Korea. However, it should be noted that these results critically depend on the assumption on the degree of screen quality degradation of HD free terrestrial channels which will be caused by the introduction of MMS.1
Il ruolo del “Partenariato Pubblico Privato” in Italia e in Francia dopo il NextGenerationEU- Riflessioni comparatistiche
No full textThe economic and social damage caused by the pandemic by COVID-19 has pushed the European Union to adopt a temporary and exceptional economic instrument, called NextGenerationEU. As stated in the institutional website "NextGenerationEU is more than a recovery plan, it is a unique opportunity to emerge stronger from the pandemic, transform our economies and societies and achieve a Europe that works for all". Given this, the study, adopting a comparative approach, aims to focus on some of the aspects considered of greatest interest in the Plans drawn up by France and Italy, having particular regard to the institution of the Public Private Partnership
The Development of Venture Capital Industry and Role of Government in Korea: Venture Boom vs. Post-Boom
No full textCHAPTER 5 / Suil Lee
The Development of Venture Capital Industry and Role of Government in Korea: Venture Boom vs. Post-Boom
1. Introduction
2. Venture Capital Industry in Korea
3. Data
4. Fund-raising and the Role of Government
5. Investment and the Role of Government
6. Conclusion
- Appendix
Surface Modification of Electrocatalyst for Optimal Adsorption of Reactants in Oxygen Evolution Reaction
No full textTechnological development after the industrial revolution has improved the quality of human life, but global energy consumption continues to increase due to population growth and the development of fossil fuels. Therefore, numerous studies have been conducted to develop sustainable long-term and renewable alternative energy sources. The anodic electrode, which is one of the two-electrode system components, is an essential element for effective energy production. In general, precious metal-based electrocatalysts show high OER reactions from the anodic electrode, but it is difficult to scale up due to their low abundance and high cost. To overcome these problems, transition metal-based anodic electrodes, which exhibit advantages with respect to their low cost and high catalytic activities, are in the spotlight nowadays. Among them, stainless steel is a material with a high ratio of transition metal components, i.e., Fe, Ni, and Cr, and has excellent corrosion resistance and low cost. However, stainless steel shows low electrochemical performance due to its slow sluggish kinetics and lack of active sites. In this study, we fabricated surface modified electrodes by two methods: (i) anodization and (ii) hydrogen peroxide (H2O2) immersion treatments. As a result of comparing the two methods, the change of the electrode surface and the electrochemical properties were not confirmed in the H2O2 immersion method. On the other hand, the porous electrode (PE) fabricated through electrochemical anodization shows a low charge transfer resistance (Rct) and high OER activity due to its large surface area compared to the conventional electrode (CE). These results confirm that the synthesis process of H2O2 immersion is an unsuitable method for surface modification. In contrast, the PE fabricated by anodization can increase the OER activity by providing high adsorption of reactants through surface modification
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