[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

The emergence of semiconductor nanocrystals as the building blocks of nanotechnology has opened up new ways to utilize them in next generation solar cells. This paper focuses on the recent developments in the utilization of semiconductor quantum dots for light energy conversion. Three major ways to utilize semiconductor dots in solar cell include (i) metal−semiconductor or Schottky junction photovoltaic cell (ii) polymer−semiconductor hybrid solar cell, and (iii) quantum dot sensitized solar cell. Modulation of band energies through size control offers new ways to control photoresponse and photoconversion efficiency of the solar cell. Various strategies to maximize photoinduced charge separation and electron transfer processes for improving the overall efficiency of light energy conversion are discussed. Capture and transport of charge carriers within the semiconductor nanocrystal network to achieve efficient charge separation at the electrode surface remains a major challenge. Directing the future resear...

http://wiki.phy.queensu.ca/shughes/images/d/d1/Quantum_Dot_Solar_Cells._Semiconductor_Nanocrystals_as_Light_Harvesters.pdf

Quantum Dot Solar Cells. Semiconductor Nanocrystals as Light Harvesters

Transparent conductors as solar energy materials: A panoramic review

The electrolyte for QDSSCs is normally a polysulfide, S2−/Sx2−, redox couple. This couple plays an important role for the regeneration of quantum dots. This study examined the effects of the electrolyte for CdS/CdSe QDSSCs. Electrolytes consisting of 1M Na2S, 2M S in a methanol and water-mixed solution at a 7: 3 ratio with or without additives such as KCl, NaOH, KOH and NaCl were used for QDSSC. The electrolyte with NaOH showed the highest conversion efficiency, 3.18%. The reasons for the improved photovoltaic characteristics were analyzed using a range of techniques.

/pdf/the-effects-of-electrolyte-additives-on-the-cell-3disvbzoyy.pdf

The effects of electrolyte additives on the cell performances of CdS/CdSe quantum dot sensitized solar cells

Effect of Acetic Acid in TiCl4Post-Treatment on Nanoporous TiO2Electrode in Dye-Sensitized Solar Cell

Developing efficient and stable perovskite solar cells (PSCs) in open atmosphere desperately requires robust hole-transporting material (HTMs) with high hole conductivity and rich hydrophobicity. Here, we present two dopant-free, highly hydrophobic, donor−π–acceptor conducting polymeric HTMs by interconnecting three monomer units of 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene, pyrrolo[3,4-c]pyrrole-1,3-dione, and [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl] (TT) named as R1 and two monomer units of [4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl] and TT named as R2. These two R1 and R2 HTMs integrated in PSCs exhibit an excellent photovoltaic performance of ∼15.8 and ∼13.5% at open atmospheric conditions, respectively. This distinguished photovoltaic performance is strongly correlated with their hole mobility, solubility, and energetic alignment with perovskite valence band. Briefly, the excess thiophene rings with extended alkyl chains in R1 brought a significant impact on photovoltaic performance due to (i) S-based heterocyclic thiophene strengthening the interaction with the perovskite/HTM interface and increasing its conductivity, (ii) a retarded recombination rate, (iii) high solubility helping to obtain uniform film coverage over perovskite, (iv) the highest occupied molecular orbital level being well aligned with perovskite energy band and (v) increased hydrophobicity. Except the top gold metal contact, the complete PSC device was fabricated in an open atmosphere from a low-temperature solution process and these dopant-free HTMs pave the way for attaining stable and efficient PSCs toward potential applications.

Open Atmosphere-Processed Stable Perovskite Solar Cells Using Molecular Engineered, Dopant-Free, Highly Hydrophobic Polymeric Hole-Transporting Materials: Influence of Thiophene and Alkyl Chain on Power Conversion Efficiency

Nitrogen-doped porous carbon materials have excellent oxygen reduction reaction (ORR) activities due to their synergistic effects caused by the electron-accepting ability of the adjacent sp2 bonded carbon atoms leading to the redistribution of charge density. However, the nitrogen doping in the carbon matrix usually involves a tedious chemical synthesis process with toxic compounds. So, the synthesis of nitrogen-doped carbon from nitrogen-containing biomass with simpler carbonization methods would be advantageous. Herein, we report a facile synthesis of nitrogen-enriched porous activated carbon from mandarin peel biomass. The prepared carbon possesses uniform pore distribution, and a highly mesoporous and defective nature with enriched nitrogen and oxygen species over the carbon surface. The excellent ORR activity is confirmed by the rotating ring electrode (RDE) measurements. The onset potentials of ORR are 0.83, 0.81, and 0.87 V vs. RHE and the half-wave potentials are 0.7, 0.71, and 0.75 V vs. RHE for open-air-, KOH- and NaOH-treated samples, respectively. All the samples follow the conventional four-electron transfer process with good stability in an alkaline medium. We have observed a correlation between the onset potential and nitrogen content of carbon. Moreover, the kinetic current increases with an increase of specific surface area due to higher electrochemically active surface sites. The honeycomb-like morphology allows the electrolyte to penetrate through the porous network and enhance the ORR activity. This study reveals a trade-off between nitrogen content, porous texture, and surface-active sites.

Interplay between porous texture and surface-active sites for efficient oxygen reduction reactions in N-inherited carbon

Water has been an inevitable part of human life and its civilization, and water contamination is caused by pollution from industrial wastes such as effluents, dyes, and heavy metals and sewage water due to human activities. Therefore, cost-effective treatment of wastewater has to be carried out without giving any by-products. This chapter is aimed at explaining the different ways of electrochemically treating the wastewater and degrading the contaminants. Electrochemical treatment is advantageous over other methods as it is inexpensive and is a green technique. The mechanism of degradation through anodic oxidation has been explained in details. The incorporation of microorganisms toward water treatment and using them for different kinds of sensors to detect the contaminants opens a new window to address this issue. Along with microorganisms, nanomaterials and ionic liquids are also used in sensing the pollutants and in removing and converting them into energy as well.

Kandasamy Prabakar

Papers

The effects of electrolyte additives on the cell performances of CdS/CdSe quantum dot sensitized solar cells

Effect of Acetic Acid in TiCl4Post-Treatment on Nanoporous TiO2Electrode in Dye-Sensitized Solar Cell

Open Atmosphere-Processed Stable Perovskite Solar Cells Using Molecular Engineered, Dopant-Free, Highly Hydrophobic Polymeric Hole-Transporting Materials: Influence of Thiophene and Alkyl Chain on Power Conversion Efficiency

Interplay between porous texture and surface-active sites for efficient oxygen reduction reactions in N-inherited carbon

Electrochemical Aspects for Wastewater Treatment