다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.

TiO2 nanotubes: synthesis and applications.

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

Photoelectrochemical (PEC) cells offer the ability to convert electromagnetic energy from our largest renewable source, the Sun, to stored chemical energy through the splitting of water into molecular oxygen and hydrogen. Hematite (α-Fe(2)O(3)) has emerged as a promising photo-electrode material due to its significant light absorption, chemical stability in aqueous environments, and ample abundance. However, its performance as a water-oxidizing photoanode has been crucially limited by poor optoelectronic properties that lead to both low light harvesting efficiencies and a large requisite overpotential for photoassisted water oxidation. Recently, the application of nanostructuring techniques and advanced interfacial engineering has afforded landmark improvements in the performance of hematite photoanodes. In this review, new insights into the basic material properties, the attractive aspects, and the challenges in using hematite for photoelectrochemical (PEC) water splitting are first examined. Next, recent progress enhancing the photocurrent by precise morphology control and reducing the overpotential with surface treatments are critically detailed and compared. The latest efforts using advanced characterization techniques, particularly electrochemical impedance spectroscopy, are finally presented. These methods help to define the obstacles that remain to be surmounted in order to fully exploit the potential of this promising material for solar energy conversion.

Solar Water Splitting: Progress Using Hematite (α‐Fe2O3) Photoelectrodes

Lignocellulosic biomass: a sustainable platform for the production of bio-based chemicals and polymers

One-dimensional nanostructures exhibit quantum confinement that leads to unique electronic properties, making them attractive as the active elements for various applications. Iron oxide (α-Fe2O3 or hematite) nanotubes are of particular interest in catalysis, sensor devices, Li-ion battery, environmental remediation and photocatalysis. Here, we report a simple sonoelectrochemical anodization method to grow smooth and ultrathin (5−7 nm thick) Fe2O3 nanotube arrays (3−4 μm long) on Fe foil in as little as 13 min. The prepared catalyst has shown tremendous potential to split water to generate hydrogen under solar light illumination. A photocurrent density of 1.41 mA/cm2 is observed for hematite nanotube arrays with more than 50% being contributed by the visible light components of the solar spectrum.

Water Photooxidation by Smooth and Ultrathin α-Fe2O3 Nanotube Arrays

The production of energy from renewable and waste materials is an attractive alternative to the conventional agricultural feed stocks such as corn and soybean. This paper describes an approach to extract oil from spent coffee grounds and to further transesterify the processed oil to convert it into biodiesel. This process yields 10-15% oil depending on the coffee species (Arabica or Robusta). The biodiesel derived from the coffee grounds (100% conversion of oil to biodiesel) was found to be stable for more than 1 month under ambient conditions. It is projected that 340 million gallons of biodiesel can be produced from the waste coffee grounds around the world. The coffee grounds after oil extraction are ideal materials for garden fertilizer, feedstock for ethanol, and as fuel pellets.

Spent Coffee Grounds as a Versatile Source of Green Energy

A coupled semiconductor material is prepared by filling one-dimensional (1D) titania (TiO2) nanotubes (NTs) with cadmium sulfide (CdS) nanoparticles (NPs). Self-assembled TiO2 NTs (length = 550 nm, diameter = 80 nm) are prepared by the sonoelectrochemical anodization method. These NTs are functionalized with CdS NPs by a single-step electrodeposition method. This material harvests solar light in UV as well as visible light (up to 510 nm) region. An eight to 9-fold enhancement in photoactivity is observed using CdS functionalized TiO2 NTs compared to pure TiO2 NTs and commercial P25 NPs. This methodology will be useful in designing multijunction semiconductor materials confined inside 1D nanochannels.

Synthesis of Coupled Semiconductor by Filling 1D TiO2 Nanotubes with CdS

This paper describes the design of a photoelectrochemical (PEC) cell using carbon-doped titanium dioxide (TiO2-xCx) nanotube arrays as the photoanode and platinum, Pt nanoparticles incorporated in TiO2 (titania) nanotube arrays, as the cathode. The PEC cell is found to be highly efficient (i.e., gives good photocurrent at a low external bias, jp = 2.5−2.8 mA/cm2 at −0.4 VAg/AgCl), inexpensive (only 0.4 wt % Pt on TiO2), and robust (continuously run for 80 h without affecting the photocurrent) for hydrogen generation by water splitting under the illumination of simulated one sun intensity. The synthesis of the photoanode is carried out by the sonoelectrochemical anodization technique using aqueous ethylene glycol and ammonium fluoride solution. This anodization process gives self-organized hexagonally ordered TiO2 nanotube arrays with a wide range of nanotube structure, which possess good uniformity and conformability. As-synthesized titania nanotubes are annealed under reducing atmosphere (H2), which conv...

Design of a Highly Efficient Photoelectrolytic Cell for Hydrogen Generation by Water Splitting: Application of TiO2-xCx Nanotubes as a Photoanode and Pt/TiO2 Nanotubes as a Cathode

Mano Misra

Papers

Water Photooxidation by Smooth and Ultrathin α-Fe2O3 Nanotube Arrays

Spent Coffee Grounds as a Versatile Source of Green Energy

Synthesis of Coupled Semiconductor by Filling 1D TiO2 Nanotubes with CdS

Design of a Highly Efficient Photoelectrolytic Cell for Hydrogen Generation by Water Splitting: Application of TiO2-xCx Nanotubes as a Photoanode and Pt/TiO2 Nanotubes as a Cathode

A novel method for the synthesis of titania nanotubes using sonoelectrochemical method and its application for photoelectrochemical splitting of water