(215g) Nickel Nanoparticles Embedded N-Doped Carbon Nanotubes As Biocompatible Electrocatalysis for CO2 Conversion

Nickel Nanoparticles
Embedded N-Doped Carbon Nanotubes as biocompatible electrocatalysis for CO₂
conversion

Siyuan Xiu, Gang Li, Yang Hou, Zhongjian Li*

College
of Chemical and Biological Engineering

Zhejiang
University

Hangzhou,
China

Email:
zdlizj@zju.edu.cn

Electricity generated
from renewable energy, mainly solar and wind power, has drawbacks of
discontinuity and fluctuation limited by natural conditions. It is an
attractive strategy to store electrical energy in the form of chemical energy. Moreover,
the capture and utilization of CO₂ contributes to eliminate the
greenhouse effect. Water splitting-biosynthetic hybrid system for CO₂
conversion has been proved to be a promising technology for converting CO₂
into various chemical commodities and storing sustainable electricity into
chemical energy simultaneously. The hybrid bio-inorganic system combines
hydrogen evolution reaction (HER) catalysts with H₂-oxidizing autotrophic
microorganisms. H₂ is produced at the cathodes with abiotic HER
catalysts, then functions as an energy carrier and electron donor for
hydrogen-oxidizing microorganisms. Intimate coupling of electrocatalysts and
biosynthesis requires the catalysts possess both high catalytic performance and
excellent biocompatibility, which is a bottleneck of the hybrid system. In this
study, a complex of Ni nanoparticles embedded in N-doped carbon nanotubes
(Ni@N-C) is synthesized as a HER electrocatalyst and is coupled with a hydrogen
oxidizing autotroph, Cupriavidus necator
H16, to convert CO₂ to poly-b-hydroxybutyrate(PHB). In Ni@N-C, the
Ni nanoparticles are encapsulated in N-C nanotubes, which prevents bacteria
from direct contact with Ni and inhibits Ni²⁺ leaching. As a result,
Ni@N-C exhibits excellent biocompatibility and stability. The maximal PHB
production of 384.30¡À6.53 mgL^-1 with a maximum PHB production rate
of 207.86¡À4.03 g^-1m^-2L^-1day^-1 were obtained,
which is comparable to that of Pt/C. Our work demonstrates that this type of
nanoconfined HER electrocatalysts reaches an excellent balance between
electrocatalysis and biocompatibility through rational catalyst design.

Figure
1 TEM of the Ni@N-C catalyst.

Figure
2 PHB c) PHB concentration, d) PHB content of dry cell weight