Use of Biological Materials and Biologically Inspired Materials for H2 Catalysis

2008 DOE Hydrogen Program

DOE Project ID#: PD34

John W. Peters (PI),Trevor Douglas,and Mark Young.

Department of Chemistry and Biochemistryand

Center for Bioinspired Nanomaterials

Montana Palladium Research Initiative:

This presentation does not contain any proprietary or confidential information

Overview

• Start - Aug. 2006• End - Dec. 2008

Barriers addressed– Stability/Durability– Oxygen Sensitivity– Electron Donors – Coupling

• Total project funding$1,303,041

– DOE $1,031,433 • Montana State UniversityPartners

Timeline

Budget

DOE Project ID#: PD34

Approaches

Biological catalysts (Hydrogenases)

Nanoparticle biomimetic catalysts

Couple Different Catalyst Systems for Light Driven Hydrogen Generation

Objectives1. Optimize the hydrogenase stability and electron transfer2. Optimize the semiconductor nano-particle photocatalysis,

oxygen scavenging, and electron transfer properties of protein nano-cages

3. Gel/Matrix immobilization and composite formulation of nano-materials and hydrogenase

4. Device fabrication for H2 production

Approach:Biological and Biomimetic Catalysts

for H2 production

Hydrogenase Enzymes(protein architecture protectingMetal sulfide active site)

Protein encapsulatednano-catalyst

Coupled Reactions to Generate Hydrogen

catalyst for hydrogen

production

GOAL: use biological catalysts and develop biomimetic catalysts with a variety of sacrificial electron donors or electrochemical source of e– to produce H2

2 H+

H2e–

Issues and Barriers: Catalyst Stability

• Durability – shelf life• Reusability• Product Based Inhibition• Oxygen tolerance / resistance• Susceptibility to proteolytic inactivation• Optimization – electron transfer, pH, ionic strength,

mediators

H2 2H+ + 2 e-

C. pasteurianum Desulfovibrio gigas

←→

Hydrogenases: Highly evolved finely tuned catalysts for hydrogen oxidation and proton reduction (hydrogen production)

“H Cluster” NiFe ClusterCellular location

Membrane AssociatedSolublePeriplasmicCytoplasmic

Microorganisms:

hydrogen, acetate-grown, methanogenic, green, purple, cyanobacteria; algae; fungus.

Electron microphotograph of hydrogenase complexes from T. roseopersicina negatively stained with 2% uranyl acetate

Cryo reconstruction of hydrogenase from T. roseopersicina at ~33 Å.

Stable NiFe hydrogenase from purple sulfur bacteria form supermolecular structures

Properties Thiocapsaroseopersicina

Large subunit 64kDaSmall subunit 34kDaTemperature optimum , °С 80ºCStability to Oxygen stable

45° 45°

Encapsulation of purified active hydrogenasesin tetramethyl ortho silicate gels

- Nanoscopic encapsulation;- Immobilization of unaltered enzyme- “Heterogeneous material”

Hydrogenase Solution Gel Solution/Gel (%)

C. pasterianum (extract) 12550 7581 60.4±16

L. modestogalophilus 9150 6175 67.5±9

T. roseopersicina 12600 8834 70.1±3

Recovery of hydrogenase activity* encapsulated in Sol-Gel

•Activity measure at 25º C indicated in nmol/min/mg protein. Values represent average rate over a four-hour period.

020406080

100120

0 1 2 3 4

times, weeks

% a

ctiv

ity

CpILm

Sol-gel encapsulated hydrogenases from C. pasterianum (CpI) and L. modestogalophilus(Lm) retain activity for a month.

Hydrogenase stability can be enhanced by gel encapsulation Increased half-life and increased temperature stability

0

20

40

60

80

100

120

25 39 58 79 87 95

temperature, 0C

% a

ctiv

ity

CpI-gelLm-gelCpI-solLm-sol

Stability of hydrogen production activity of CpI and Lm hydrogenases enhanced when encapsulated

02000400060008000

100001200014000

Solution Sol-Gel

n m

ol H

2/m

in p

er m

g pr

otei

n

- protease+ protease

Encapsulated hydrogenases are insensitive to proteases.

Hydrogenase can be reused and recycled in gels

Reduced methyl viologen iscaptured by the gel presumably due to electrostatic interactions between the positively charged methyl viologen and the negatively charged Sol-Gel. We are examining using high ionic strength solutions and doped Sol Gel preparations to maximize electron flux.

Multiple additions of reductionMaximum yields obtained when hydrogen is removed from the system presumably relieving product based inhibition

Activity of hydrogenase encapsulated in silica-gel in presence MV as a mediator in solution at pH 8.0

-200

20406080

100120140160

0 50 100 150 200 250

Time, min

nmol

H2 /

mg

prot

ein

+ h2ase-h2ase

+ DT

change gas phase

+ DT

Biomimetic Catalysts - Synthesis of Pt0

Encapsulated Within a Protein Cage Architecture

100 nm 100 nm

+ K2PtCl4

Reducing agent (DMAB/ BH4

–

)pH 6.5, 65oC

30252015105Volume (mL)

Abs

orba

nce

280 nm 350 nm

Hsp

250Pt Hsp

1000Pt Hsp

A

B

C

30252015105Volume (mL)

Abs

orba

nce

280 nm 350 nm

Hsp

250Pt Hsp

1000Pt Hsp

A

B

C

Small heat shock proteinfrom Methanococcus jannaschii

Size exclusionchromatography

Transmission electron microscopy

Coupled Catalysis for H2 Production

4x10 6

3

2

1

0

H2/ c

age

150010005000Time ( sec )

Initial rates (Pt): 4.47x103 H2/sec/Hsp 1.5 x 104 H2/sec/ferritin

(Hydrogenase => 6 x103H2/sec/hydrogenase)

EDTA+

EDTA

1/2H2MV2+

MV+ H+

Pt Colloid

[Ru(bpy)3]2+*[Ru(bpy)3]2+

[Ru(bpy)3]3+

hv

Thermally stable 80-90ºCOxygen insensitive

Control of Pt cluster size(monitored by NCMS) correlation between activity and

cluster size

23+

23+

23+

23+

23+

23+23+

23+

23+

Rel

ativ

e ab

unda

nce

(%)

m/z

Mass spectra Pt2+ bound (black) and Pt0

(red) cages - loading of Pt2+ (0, 12, 24, 48, 100, and 200 Pt/cage). Charge state 23+ are shown

0 Pt2+

12 Pt2+

24 Pt2+

48 Pt2+

100 Pt2+

200 Pt2+

Pt2+ bound

Pt0

0 30 60

0.00

0.05

0.10

0.15

0.20

H2 p

rodu

ced

(um

oles

)Time (min)

H2 production

Moving beyond Pt…Pd and Metal Sulfide Nanoparticles as H2 Catalysts

3.0x105

2.0

1.0

0.0

H2/M

etal

20151050Time (min)

Pt Pd

Pd particles show significantly lower activity than Pt

Pd

MoxOy MoSx

200 nm200 nm

2.0x10-4

1.5

1.0

0.5

0.0

i (A

)

-1200-1000-800-600-400-2000E (mV) vs Ag/Ag 2S

H+H+

GCE

flow

of e

lect

rons

H2

Thermally stable 80-90ºCOxygen insensitive

Polymer gels – control midpoint potential

**

n

N N

γ-butyrolactone, 20 hours @ 80o C

**

n

**

N

N

n

N N CH3,

**

n

N

N

CH3

Cl

and

poly(vinyl benzyl chloride)

N

N

N

N

CH3

N

N

CH3

N

N

Poly(vinylbenzyl chloride)

Poly(vinylbenzyl chloride)

N

N

CH3

Non-Crosslinked Viologen Unit

Crosslinked Viologen Unit

NH

N3OBr

Hepes, pH 6.5

SH

SHHS

HSS

SS

SNH

N3

HNN3

O

ONHN3

HN

N3

O

O

N N

S

SS

SNH

HN

O

ONH

HNO

O

NNN N

N

N NN

N

N

NN N

N

N

NNN

N

N

Chemical incorporation of protein catalysts

Long-Term Goal – Device for hydrogen production – composite materials (nanoparticles

and hydrogenase enzymes)

Design and Fabrication of prototype devices

Transparent window

backing window

hν

Poly(viologen) Gelmatrix

N N

* *

n

n

Imobilized Catalyst

NN

N NN

N

Ru

2+

Ru(pby)32+ photosensitizor

+

EDTA+

EDTA

1/2H2MV2+

MV+ H+

Pt Colloid

[Ru(bpy)3]2+*[Ru(bpy)3]2+

[Ru(bpy)3]3+

hv

Based initially on the solution assay

-1.5x10-3

-1.0

-0.5

0.0

0.5

1.0

Cur

rent

(A)

-1200-1000-800-600-400-2000 E (mV)

2M Acetate pH 4.0HFn controlHFn-1000PtPt colloid Pt Wire

Protein shell requires an overpotential of ~200mV compared to naked Pt colloid

2.0x10-4

1.5

1.0

0.5

0.0

i (A

)

-1200-1000-800-600-400-2000E (mV) vs Ag/Ag 2S

H+H+

GCE

flow

of e

lect

rons

H2

Attachment of MoSx - protein cage to GCE - H2 production

Cyclic Voltammetry to probe e– transfer to catalysts

working electrode: InSnO or carbon

H2ase:nanotube:sol-gel

H2 (g)

buffered solution

Potentiostat

r e f e r e n c e e l e c t r o d e

c o u n t e r e l e c t r o d e

Carbon nanotubes incorporated into Sol Gels

Enhance electron transferFacilitate electron transfer between immobilized mediators

and hydrogenaseFacilitate electron transfer between electrodes and

hydrogenase in devices

Activity of H2ase encapsulated in silics-gel at pH 5.6

0

200

400

600

800

1000

1200

0 10 20 30 40 50 60

Time, min

n m

ol H

2 / m

g pr

otei

n

+ h2ase- h2ase

+ DT

+ DT

Biomimetics HydrogenasesContinuous hydrogen production > 60 min

O2 tolerance Insensitive to O2

InsensitiveReversibly oxidized in the presence ofO2 and retains activity

Efficiency of photon-to-H2

Current properties in the context of technical targets

Currently assessing*

•Reported quantum efficiency of Ru(bpy)32+ photoreduction of MV2+ to MV+

using EDTA as sacrificial reductant is 25%. (Johansen, O. et al Chem. Phys. Letters,1983, 94, 113-117)

•We are currently assessing the efficiency of the MV+ to H2 with both the hydrogenases and synthetic systems using devices described.

Currently assessing*

> 60 min

SummaryUse of biological and biomimetic catalysts for

H2 productionIncorporation of hydrogenase and mimetics

into stabilizing matricesIncorporation of hydrogenase and mimetics

into electroactive poly(viologen matrices)Initial incorporation of catalyst systems into

devices

Future Work

Establish Benchmarks for Hydrogen production efficiency

Incorporate catayst(s) into poly(viologen)matrices(electrostatic/covalent)

Evaluate Hydrogen production efficiency (electrochemical, photochemical, chemical reducing equivalents)

Incorporate solution chemistry into deviceEvaluate device for durability and sustained H2

production