Inorganic Nanostructured Materials

Gerasimos Armatas

Research activitiesResearch activities focused on design and synthesis of nanostructured mesoporous materials and their applications, including:•Nanoporous metal oxides using ‘soft’ or ‘hard’ templated (nanocasting) self-assembly approaches•Periodically ordered mesoporous polyoxometalate-containing frameworks•Nanostructured inorganic semiconductors• Structural and chemical modification of

nanocomposite structures• Applications in heterogeneous catalysis,

absorption, optoelectronics and gas separation

Hexagonal Mesoporous Zirconia-POM Nanocomposites

0.0 0.2 0.4 0.6 0.8 1.00

10

20

30

40

50

Nitr

ogen

ads

orbe

d (c

m3/g

ST

P)

Relative pressure (P/Po)

0 5 10 15 20 25 30 35 400.000

0.004

0.008

0.012

0.016

0.020

Por

e vo

lum

e (c

m3/g

-nm

)

Pore width (nm)

c103 m2/g

Dp=5 nm

Substrate Conversion(%)

TOF(h-1)

Selectivityepoxide:alcohol:ketone

cyclooctene 82 41.0 100:0:0

cyclohexene 30 7.5 47:43:10methyl-cyclohexene 26 6.5 81:8:11

Styrene 30 7.5 5:0:95methyl-styrene 28 7.0 39:61:0

Epoxidation of alkenes with H2O2 catalyzed by 37wt% PMo12/ZrO2

Other catalytic systems include mesoporous ZrO2/[SiW12O40]4-, ZrO2/[PW12O40]3-, Al2O3/[PW12O40]3-, TiO2/[W10O32]4- nanocomposites.

G.S Armatas et el., J. Mater. Chem. 2010, 20, 8631;G.S.Armatas et el., J. Mater. Chem. 2011, 21, 2997

SBA-15Cr(NO3)3

H3PMo12O40

SBA-15Cr2O3/HPMo

Cr2O3/HPMo

400oC HFb

Mesoporous Cr2O3-Phosphomolybdic acid Solid Solution Frameworks

1000 800 600 400 200 0

Photo

ele

ctron inte

nsity (a.u

.)

Binding energy (eV)

Mo 3d

O 1s

Cr 2p

Mo 3p

Cr 3pP 2p

240 236 232 228 224

Photo

ele

ctr

on inte

nsity (

a.u

.)

Binding energy (eV)

Mo 3d

592 584 576 568

Photo

ele

ctr

on inte

nsity (

a.u

.)

Binding energy (eV)

Cr 2p

OO H

63wt% HPMo/Cr2O3

H2O2, 50 oC

Catalytic oxidation of 1-phenylethanol*

*Conv. 87%, TOF=103 h-1, 5 min, CH3CN

Other materials are mesoporous Co3O4/[PW12O40]3-, CeO2/MoO3, CeO2/Bi2O3.

Armatas et el., Chem. Mater. 2010, 22, 5739.

c. XPS

Mesoporous Germanium Semiconducting Frameworks (collaboration with Northwestern University, USA)

bulk nano

WT~1.3 nmWT~1.5 nmWT~2 nm

Decreasing pore wall thickness, increasing energy band-gap

Eg=1.86 eV Eg=1.92 eV Eg=1.97 eV

CB

VB

Band gap Evolution with Wall Thickness in a Nanostructured Semiconductor

G.S. Armatas, M.G. Kanatzidis, Nano Lett. 2010, 10, 3330

Collaborators• Prof. M. Kanatzidis (NU)• Prof. M. Louloudi (UoI)• Prof. P. Pomonis (UoI)• Prof. K. Triantafyllidis (AUTH)• Prof. I. Lykakis (AUTH)• Prof. M. Stratakis (UoC)• Dr. P. Chupas (ANL)

Funding