We are making nanostructured materials such as quantum dots, nanotubes, nanorods, and nanolamellae for detecting volatile organic compounds (VOCs) and pollutant gases in the atmospheric air.Controlling the size and morphology of nanomaterials leads to improved sensitivity and selectivity.
Synthesis of monodispersed SnO2 nanocrystals and WO3 nanolamellae for gas sensing
Application of ionic conductors for electrochemical devices
Na3Zr2SiPO12 is a sodium ion conducting material, which is known as NASICON (Na ion Super Ionic Conductor）developed by Prof. Goodenough at the University of Texas.We have developed a high performance NASICON-based CO2 sensor that can detect 1 to 10000 ppm CO2 in air without interference from other gases like water and hydrocarbons.Our current interest is to analyze the concentrations of standard organic gases by combining combustion catalysts with the CO2 sensor.The catalytic combustion of organic gases at the catalyst layer produces CO2, which is then detected by the CO2 sensor and the sensor signal is transduced as the concentration of organic molecules in the gas, as shown in the scheme.
Anal. Chem. 82, 3315-3319 (2010).
Anal. Methods 3, 1887-1892 (2011).
Analysis of a standard gas containing propofol using a CO2 sensor combined with combustion catalysts
Organic-inorganic hybrid for photocalysis at liquid-liquid interfaces
We have demonstrated that heteropolyacids combined with surfactants work as a photocatalyst at an interface between an organic solution and water containing noble metal ions.
This reaction system preferentially produces sheet-like noble metal particles (nanosheets), which is indicative of the occurrence of the reaction at the interface.
The develop method is applicable to photo-recovery of noble metals from waste solutions.This is a potentially green and cheap method in that catalysts can be recycled, few amounts of chemicals are used, and the reaction is driven by light.
We also found that the addition of thiol compounds significantly improved the recovery rate because of strong interaction between metals and thiols.
Langmuir 24, 7648-7650 (2008).
J. Phys. Chem. C 113, 19986-19993 (2009).
Langmuir 29, 2128?2135 (2013).
Photorecovery process using a heteropoyacid-surfactant hybrid as a photocatalyst
Printed solar cells based on sulfide nanocrystals
Cu2ZnSnS4 (CZTS) has been attracting much attention because of its good light absorption properties.Another advantage is that CZS is not composed of toxic or rare elements, which makes CZTS a promising absorber layer in compound semiconductor solar cells.We are currently synthesizing CZTS nanocrystals with good quality, which can be applied to thin film fabrication.Making thin films from nanocrystals using a simple coating process is expected to drastically decrease the fabrication cost of compound semiconductor solar cells.Major challenges are development of feasible, reproducible routes to get high quality heterojunction films.
J. Phys. Chem. C 118, 804-810 (2014).
Synthesis of Cu2ZnSnS4 nanocrystals and their application for printed solar cells
Tunable physical properties of supercritical fluids
Separation and reaction processes in supercritical fluid
One of our many research interests deal with the chemical engineering aspects of sub and supercritical fluid technologies and their applications to effective biomass utilization, bioresources recovery, chemical recycling and development of energy-saving processes. Specifically, supercritical fluids are applied to extraction of valuable compounds from natural products, fractionation of essential oils, biomass decomposition, bio-oil production, plastic recycling and bitumen upgrading to name a few.
Supercritical Fluid Technology for Energy and Environmental Applications, 235-247 (2014)
Sep. Pur. Tech., 125, 319-325 (2014)
J. Agric. Food Chem. 61 (24), 5792-5797 (2013)
J. Supercrit. Fluids, 66, 215-220 (2012)
Extraction of natural products using SCCO2 and subcritical water
Mechanism of solvent-free microwave extraction of essential oil
Microwave-mediated separation and reaction processes
Microwave irradiation, under ambient or high pressure conditions, is applied to extraction of functional natural products and to synthesis of biofuels such as biodiesel, bioETBE and GTBE.
Green Energy and Technology, 117-130 (2013)
Ind. Eng. Chem. Res., 52, 7940-7946 (2013)
Chemical Engineering and Science, 1(1), 122-16 (2013)
Biofuel Production-Recent Developments and Prospects, 415-436(2011)