Shigenori Fujikawa

Abstract Direct CO 2 capture from the air, so-called direct air capture (DAC), has become inevitable to reduce the concentration of CO 2 in the atmosphere. Current DAC technologies consider only sorbent-based systems. Recently, there have been reports that show ultrahigh CO 2 permeances in gas separation membranes and thus membrane separation could be a potential new technology for DAC in addition to sorbent-based CO 2 capture. The simulation of chemical processes has been well established and i

A novel procedure for fabricating nanoarchitectures of ultrathin titania layers was developed by using assembled latex particles and tobacco mosaic viruses (TMV) as templates. Latex particles and TMVs were assembled on the surface and then covered with ultrathin titania films by the surface sol−gel process. When the surface-covered latex template was subjected to an oxygen plasma treatment, hollow titania spheres connected with each other via nanotubes were formed at the original deposition of t

Fabrication and gas permselective behavior of free-standing polydimethylsiloxane (PDMS) nanomembranes are discussed. The largest CO2 permeance is close to 40,000 GPU (the highest one ever reported) at 34-nm membrane thickness without losing the CO2/N2 selectivity of 10–12, indicating the formation of pin-hole free nanomembranes. Fabrication and gas permeselective behavior of free-standing polydimethylsiloxane (PDMS) nanomembranes are discussed. The largest CO2 permeance is close to 40,000 GPU (t

Abstract Reducing CO 2 emissions alone will not suppress global warming, and it is necessary to capture the CO 2 that has been cumulatively emitted into the atmosphere as well. For this reason, negative CO 2 emission technology, a technology to capture CO 2 from the atmosphere, is considered essential. Especially, direct capture of CO 2 from the air, so-called direct air capture (DAC) has attracted much attention as one of promising technologies, because of the high potential capacity of CO 2 ca

We report herein fabrication of arrays of sub-20-nm silica walls via photolithography and the surface sol-gel process. A photolithographically fabricated line template on a silicon wafer was coated with a silica nanolayer using the surface sol-gel process, and then the topmost portion of the silica layer and the template were successively removed using CHF(3) and oxygen plasma, respectively, leaving the sidewalls of the silica layers remaining on the substrate. These walls were fully self-suppor

Long-term stability of the surface hydrophilicity of poly(dimethylsiloxane) (PDMS) remains a critical issue for a wide range of applications including, e.g., biomedical materials, biochip devices, and microfluidics. Although several mechanisms for recovering hydrophobicity have been proposed, none has been proven unequivocally. We discovered that the hydrophobic recovery of surface-oxidized PDMS films was accelerated when the films were stored in a closed chamber under an atmosphere containing d

Titania nanotube was prepared by nanocopying of the individual DNA double strand as template. DNA was first spread on a solid substrate, and its molecular surface was coated with an ultrathin titania layer by 3 cycles of the surface sol-gel process. Fluorescence microscopic images before and after titania coating of the DNA/YOYO-1 complex were essentially identical, showing that the titania coating did not change the chemical properties of the complex. Titania coating effectively prohibited chem

A free-standing ultrathin film of a poly(vinyl alcohol) (PVA)/titania (TiO2) composite was prepared by spin coating. The thickness of the film was adjusted to 30-50 nm by changing the spin-coating speed and the concentrations of PVA and the TiO2 precursor. A template molecule, (4-phenylazo)benzoic acid (4PABA), was introduced into the film as a mixture in the TiO2 precursor and was removed after film formation by dipping the film in aq NH3 (1%). Aqueous solutions of tetraphenylporphyrin tetrasul