Photocatalysis Laboratory

Photocatalysis Laboratory

​The main project supported by the Photocatalysis Lab aims at producing hydrogen from water using sunlight through a photocatalytic process. To this end, several key steps have been identified:

  • Establish guidelines and photocatalyst activity descriptors to select a set of potentially active photocatalysts

  • Proof of concept

  • Identify the best hit

  • Catalyst scale-up

  • Build a pilot unit for photocatalysts field test

The photocatalytic water splitting has been pioneered 30 years ago and has advanced since then through the work of various groups, including the group of Prof. Domen (the University of Tokyo). Using UV light as an irradiation source, some photocatalysts have been reported to achieve overall water splitting with a quantum efficiency much higher than 10%. However, solar light contains only 4% of its energy in the UV region while over 40% of the energy is in the visible region. In an attempt to utilize more solar energy, the research program aims at developing photocatalysts responsive in the visible region of the solar spectrum. The ultimate goal is to engineer photocatalysts with twice the current state of the art efficiency in the visible region to reach an overall 10% solar to hydrogen energy conversion efficiency. The research team (PI: Kazuhiro Takanabe) is specifically focused on improving absorption in a wide range of the visible region and to enhance quantum efficiency through:

  • The synthesis of semiconductor materials (e.g: new (oxy)nitrides) with high crystallinity and large absorption band

  • The introduction of active electrocatalysts and/or semiconductor layers

Material synthesis is achieved using a variety of types of furnaces (flow in various gas atmospheres, batch in air, rapid temperature ramping). Photocatalytic tests are conducted using recirculating and flow reactors, equipped with various light sources (high pressure Hg, Xe, solar simulator etc.) and gas chromatographies. Wavelengths are selected by using various cutoff and band pass filters. Photon numbers at each wavelength are accurately measured using various photodiodes. Liquid reactants and products are measured by HPLC for organic and inorganic compound analysis and ionic HPLC for ion analysis. Photocatalyst materials are characterized using XRD, XPS, FTIR, photoluminescence and UV-VIS spectroscopy. A series of (photo)electrochemistry equipment is available for understanding of band positions and semiconductor properties using potentiostats with various electrodes.

Facilities

  • Gas Flow reactors Brand: PID Eng & Tech,
    Model: Microactivity Catalytic Reactor
    Gas Flow reactors Isothermal Fixed bed flow reactors are used as laboratory scale reactors for catalytic screening and kinetic studies of different solid catalysts for gas phase reactions. These are generally operated under dynamic conditions, whereby the reactants are continuously fed to the reactor and products are continuously collected for analysis.
  • Potentiostat Brand: Bio-Logic SA,
    Model: VMP3
    Potentiostat The potentiostat is used for liquid phase electrochemical performance evaluation of various materials and kinetics/mass-transport studies. These are usually operated under ambient pressure conditions with controlling temperature when needed, and current-potential relationships are recorded by the instrument for the analysis.
  • pH meter Brand: Mettler Toledo,
    Model: SevenGo Duo
    pH meter The pH of aqueous solutions is measured by the pH meter. The pH meter is equipped with an electrode, potential of which is monitored for determination of pH. All the pH measurements are usually carried out at room temperature (298 K) and ambient pressure (1 atm).
  • Spectrophotometer Brand: Perkin Elmer,
    Model: Lambda 45
    Spectrophotometer This spectrophotometer is used for transmittance and absorbance measurements on liquids samples, regulatory tests requiring variable resolution, and highly light-scattering samples. The additional pre-monochromator reduces stray light by a factor of 2, providing optimum performance for turbid and light-scattering samples, such as some biological solutions and suspensions.
  • Spectrofluorometer Brand: Horiba scientific,
    Model: Fluoro-max-4
    Spectrofluorometer The Horiba FluoroMax® 4 spectrometer is a powerful tool for measuring fluorescence of solids, liquids, powders and thin films. The instrument is easy to use and is controlled by FluorEssenceTMsoftware.
    The sample is illuminated by a 150 W xenon, continuous output, and ozone-free lamp. The excitation monochrometer has an optical range of 220 – 600 nm blazed at 330 nm. The emission monochromator has an optical range of 290 – 850 nm blazed at 500 nm. The slit widths may be continuously adjusted though the software. The FluoroMax 4 has two detectors.

  • Micro-Ultracentrifuge Brand: Thermo Scientific,
    Model: SORVALL MTX 150
    Micro-Ultracentrifuge Micro-ultracentrifuge offers powerful separation technology in a quiet, compact, easy-to-use benchtop design that combines advanced functionality, rotor management and controlled access in a footprint that is 20% smaller than other benchtop models. It can reach maximize of 150,000 rpm in just 80 seconds with self-locking rotor system and automatically secures the rotor to the drive shaft.
  • FTIR Spectrometer Brand: Perkin Elmer,
    Model: Spectrum 100
    FTIR Spectrometer The FTIR spectrometer is used to analyze solid catalyst samples during reaction conditions for gas phase reactions. It provides vibrational information about chemically bonded surface reaction intermediates which can give insight into the catalytic reaction mechanism. It can also be used to study liquid samples using an ATR-IR attachment.
  • Gas chromatograph (GC) Brand: Shimadzu,
    Model: GC-8A
    Gas chromatograph (GC) Gas chromatograph is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture (the relative amounts of such components can also be determined). In some situations, GC may help in identifying a compound.
  • Photocatalytic glass reactor system Brand: Custom made from Makuhari Rikagaku Glass Inc.,
    Model: Homemade design
    Photocatalytic glass reactor system The custom designed photocatalytic reactor uses a top-down irradiation system where the photocatalytic reaction is performed in a recirculating batch reactor connected to a gas chromatography (GC) unit equipped with a vacuum line. The reactor allows for control of pressure and temperature while accurately measuring the products formed from the photocatalytic reaction.
  • Electron Paramagnetic Resonance Spectrometer Brand: ADANI,
    Model: CMS 8400
    Electron Paramagnetic Resonance Spectrometer Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a technique for studying materials with unpaired electrons. EPR is a sensitive, specific method for studying both radicals formed in chemical reactions and the reactions themselves.
  • X-Ray Powder Diffractometer (XRD) Brand: BRUKER,
    Model: D8 Advance
    X-Ray Powder Diffractometer (XRD) X-ray powder diffraction (XRD) is a rapid analytical technique primarily used for phase identification of a crystalline material and can provide information on unit cell dimensions. The analyzed material is finely ground, homogenized, and average bulk composition is determined.
  • Atomic Layer deposition system (ALD) Brand: SUGA,
    Model: SAL 3000
    Atomic Layer deposition system (ALD) Atomic layer deposition (ALD) is a thin film deposition technique that is based on the sequential use of a gas phase chemical process. ALD is considered a subclass of chemical vapour deposition. The majority of ALD reactions use two chemicals, typically called precursors. These precursors react with the surface of a material one at a time in a sequential, self-limiting, manner. Through the repeated exposure to separate precursors, a thin film is slowly deposited. ALD is a key process in the fabrication of semiconductor devices, and part of the set of tools available for the synthesis of nanomaterials.
  • Thermal evaporator Brand: Normvac,
    Model: VCM 600 V2
    Thermal evaporator Thermal evaporation is a common method of thin-film deposition. The source material is evaporated in a vacuum. The vacuum allows vapor particles to travel directly to the target object (substrate), where they condense back to a solid state. Evaporation is used in microfabrication, and to make macro-scale products such as metallized plastic film.
  • Langmuir-Blodgett system Brand: Biolin Scientific,
    Model: KSV NIMA
    Langmuir-Blodgett system A Langmuir–Blodgett system is a laboratory apparatus that is used to compress monolayers of molecules on the surface of a given subphase (usually water) and measures surface phenomena due to this compression. It can also be used to deposit single or multiple monolayers on a solid substrate.
  • Balance Brand: Mettler Toledo,
    Model: Excellence Plus
    Balance Balances are used to take the weight of a given sample of materials, from starting reagents to final products. Apart from the typical balance apparatus, these scales are surrounded by a clear box to help make accurate measurements of all types of samples. The doors of the box are equipped with motion sensors to allow for easy opening and closing.