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.
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