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What Nanoporous Supports Do We Need for Solar Light-Driven Fuel Synthesis . Direct Solar to Fuel by Solid Photocatalysts Principle:. Direct Solar to Fuel by Solid Photocatalysts. Where we are: UV light-driven Water Splitting: mixed metal oxide nanoparticles.

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what nanoporous supports do we need for solar light driven fuel synthesis
What Nanoporous Supports Do We Need for Solar Light-Driven Fuel Synthesis

Direct Solar to Fuel by Solid Photocatalysts

Principle:

direct solar to fuel by solid photocatalysts
Direct Solar to Fuel by Solid Photocatalysts

Where we are:

UV light-driven Water Splitting: mixed metal oxide nanoparticles

Kudo, J. Am. Chem. Soc.2003, 125, 3082.

Q.Y. = 56%, > 400 hours

● Direct solar to fuel works with UV light

direct solar to fuel by solid photocatalysts1
Direct Solar to Fuel by Solid Photocatalysts

Where we are: UV light-driven CO2 reduction by H2O: Isolated Ti

centers in nanoporous silicate

● Direct Solar to Fuel Works with UV Light

Anpo, Catal. Today1998, 44, 327

Frei, J. Phys. Chem. B2004, 108, 18269

direct solar to fuel by solid photocatalysts where we are visible light driven h 2 o h 2 o 2
Direct Solar to Fuel by Solid PhotocatalystsWhere we are: Visible light-driven H2O → H2 + O2

Single Component mixed metal oxide

NiInTaO3

Two-component mixed metal oxide

with shuttle (Z-scheme)

  • Water splitting with visible light observed, but very low efficiency.

Q.Y.= 0.3% at 420 nm

Arakawa, Science2001, 414, 625

Q.Y.= 0.3% at 500 nm

Kudo, Chem. Commun. 2001, 2416

direct solar to fuel by solid photocatalysts2
Direct Solar to Fuel by Solid Photocatalysts

Where we are: Visible light-driven CO2 Splitting

Binuclear photocatalytic sites on inert mesoporous oxide support

Frei, J. Am. Chem. Soc. 2005, 127, 1610

what we need
What we need

Fact:

Numerous small bandgap semiconductor photocatalysts work efficiently under visible light (λ>600 nm, q.y.>50%), but require sacrificial reagents

Lesson: no defects or ill-defined structures can be involved in energy transduction, charge migration, or catalytic transformation because they will invariably lead to loss of stored energy, charge, or chemical selectivity

How can we avoid sacrificial reagents:

  • Active moieties (light harvesting, charge separation, catalytic sites) of molecular makeup
  • Need 3-D high surface area ‘spectator’ support for the molecular functionalities with precisely arranged (Angstrom) anchoring sites and structural elements for physical separation on the nanometer scale.
  • Need to remove promptly the redox products from the reactive surface

 exploit gas-solid interface

what active molecular components are available some examples
What Active Molecular Components are Available:Some Examples

Organometallic:

Ru(bpy)32+ sensitizer/ Ni(cyclam) catalyst (CO2 to CO, H2O reduction)

Inorganic:

IrOx Clusters (H2O oxidation)

MMCT units (CO2 splitting)

slide8

Organic/Metal Oxide Hybrid Functionalities on Mesoporous Supports

side view

top view

Challenge: Incorporation of organic and polynuclear transition metal units at preselected sites and defined orientation inside silica wall

slide9

Mixed Oxide Functionalities on Mesoporous Silica Supports

Challenge: Ir oxide patches of defined composition and structure covalently linked to Co-O-Ti units inside mesoporous silica wall

solar to fuel by solid photocatalysts what needs to be done
Solar to Fuel by Solid Photocatalysts:What needs to be done

Develop methods that afford imprinting of molecular components and well-defined metal oxide clusters into walls of mesoporous nonreducible oxide supports at predetermined locations and with defined orientation

New types of templates

Methods for creating channel patterns with oxidizing/reducing sites

Mesoporous membranes

Defect-free active component/silica interface

Design new catalytic components for coupled H2O oxidation/CO2 reduction