C02 Conversion

Electrobiosynthesis for CO2 Conversion

Introduction

Fixing of CO2 through Formic Acid Synthetic Metabolic Pathways CO2 Reducing Carbon Nanotube Electrode Materials Concentration acheived (mM)

Conversation efficiency (%) Carbon paper

<0.0173

0

CF

0.112

6.07

CF-CNTs (Fe)

0.0953

3.05

CF-CNTs (Ni)

0.353

7.10

CF-CNT(Fe)

with Sn

9

10.02

CF-CNT(Ni)

with Sn

30

29.04

Our lab is developing a carbon fiber – carbon nanotube electrode for the

reduction of CO2 to formic acid: Nanotubes offers high surface area for

electrochemical reactions such as reducing

CO2 to formic acid as well as sites for enzymes or other nanoscopic catalyst to increase specificity

and reduce parasitic reactions.

Fig 2. Images of carbonized fiber and CNT coated carbon

fiber. (A) SEM of cellulose fibers, scale bar: 100m; (B)

SEM of reduced Fe particles on the surface of a cellulose

fiber, scale bar: 5m; (C) SEM of CNT-enabled carbonized

fibers with 5 min of hexane feed, scale bar: 10m; (D) SEM

of a CNT-enabled carbonized fiber with 20 min of hexane

feed, scale bar: 10m

Tab 1. Performance of different

electrodes in converting CO

2

to

formatee. (Conditions: 0.5 M

K

2

CO

3

, 1.8 V, bubbling CO

2

, cold

trap and buffer sampling.)

A single carbon fiber microelectrode with branching carbon nanotubes for

bioelectrochemical processes

Biosensors and Bioelectronics

zhao el

Research Objectives

Acknowledge

Due to climate change, extensive research world wide has been made in developing better ways of sequestering carbon dioxide. Compared

with normal photosynthesis pathway,

I

n Vito

enzyme or microbial based CO

2

fixing via electrosynthesis can provide many advantages:



Greater potential efficiency



Production of specific chemical products with minimize co-products



Operation on a variety of energy sources



Faster reaction rates than possible

In Situ

systems

In Vito

Cofactor Regeneration

and Enzyme Catalysis

Formic acid as an energy carrier provides advantage over other means

of providing electrical energy to organisms:



Formic acid and CO

2

co-factor is fully recyclable



Less volatile and more soluble then hydrogen gas



More candidate organism then direct electrode or hydrogen feeding

organism

Fig 1. Simplified schematic of electoreduction of CO2 to formic acid incorperated into a bioreactor.



The production of formic acid reducing electrodes and

incorporation into bioreactors for electrosynthetic growth of

organism for

in situ

production of chemical products



Combination of formic acid electrosynthesis, co-factor

regeneration with consortium of enzymes in multistep

in vitro

synthesis of high value chemical products

ddd

Fig 3.

Chemical route of enzymatic synthesis of methanol from CO2 with in situ

regeneration of NADH. (Abbreviations of enzymes: FDH—formate dehydrogenase;

FaldDH—formaldehyde dehydrogenase; ADH—alcohol dehydrogenase; GDH—

glutamate dehydrogenase.).

Notes: the FDH reaction could be supplied by electrosynthesis

Fig 4.Chemical route for the attachment of

enzymes and cofactor onto polystyrene

particles.

Fig 5. collision-driven

regeneration cycle of particle-

attached cofactor

In order to attain high stability and

reaction rate of multiplied enzyme

reaction, cofactor and different

enzyme can be co-immobilized on

nano-particles.

The authors thank the support of the Biotechnology Institute(BTI) grant and an

international research grand from Korean institute of Energy Technology Evaluation

and Planning.