Research team led by Prof. Jinhan Cho develops cotton fiber-based high performance biofuel cells, working with researchers from the Georgia Institute of Technology

The findings are published in Nature Communications.

▲ Prof. Jinhan Cho from Korea University, Prof. Seung Woo Lee from the Georgia Institute of Technology, and Researchers Yongmin Ko and Cheong Hoon Kwon from Korea University

The research team led by Prof. Jinhan Cho from the Department of Chemical and Biological Engineering, College of Engineering, Korea University has developed a high performance biofuel cell that uses insulating fibers and supports in vivo applications.

The research team, working with Prof. Seung Woo Lee from Georgia Institute of Technology in the US, succeeded in developing an implantable biofuel cell (BFC) after coating bare cotton fibers with metallic nanoparticles and depositing enzymes onto the fibers.

BFCs replace the catalysts often used in fuel cells with enzymes and, to generate power, the electrons created by the glucose oxidation reaction, are collected through electrodes. BFCs draw attention as potential next-generation biomedical power devices because they operate at room temperature. However, the conventional biofuel cell with its flat electrode is low in power output efficiency and biocompatibility due to its poor physical properties, including flexibility, and these shortcomings hinder the technology’s commercialization.

The research team evenly coated cotton fibers with gold nanoparticles to maintain their porous surface and succeeded in developing a high performance biofuel cell electrode. The coated metallic cotton fibers (MCFs) show extremely high conductivity without any change to their mechanical and structural properties due to the metal. In addition, the coated MCF-based hybrid BFCs with their porous structure exhibit a remarkable power density and efficiency. The research team used the sequential small-molecule ligand exchange layer-by-layer assembly. This minimizes the distance and contact resistance between the metallic nanoparticles, thus maximizing charge transfer through the electrodes and hence power output.

* Ligand: An ion or molecule that binds to a central metal atom in a complex compound

* Layer-by-layer assembly: A technique of fabricating functional nanoscale films by depositing alternating layers of oppositely charged materials

As the new BFCs can be miniaturized without requiring a membrane, their properties support in vivo applications such as implantable power supplies for cardiac pacemakers and neurostimulators.

“The cotton fiber electrode with a high power output capacity is the first case used for biofuel cells,” said Prof. Cho, adding, “The resulting biofuel cells retain good intrinsic flexibility and physical characteristics combined with high efficiency and stability. Therefore, we expect they will provide a new platform for wearable and in vivo application materials.”

This work was supported by the grant of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (MSIP) and the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education. The findings were published in Nature Communications on October 26, 2018.

* Title of the Article: High-Power Hybrid Biofuel Cells Using Layer-by-Layer Assembled Glucose Oxidase-Coated Metallic Cotton Fibers

* Main Authors: Prof. Jinhan Cho (corresponding author, Korea University), Prof. Seung Woo Lee (corresponding author, Georgia Institute of Technology, U.S.A.), Doctor Cheong Hoon Kwon (first author, Korea University) and Yongmin Ko (first author, Korea University)

(Figure 1) Illustration of preparation of the MCF electrode and BFC

(A) Preparation of the anode (top) and the cathode using the enzymes (bottom) using metallic nanoparticles and small-molecule ligand-induced layer-by-layer assembly

(B) MCF-BFCs composed of a cathode and an anode. Glucose, the fuel of the cathode is oxidized to gluconolactone by glucose oxidase, and at the anode oxygen is reduced to water, generating power.

(Figure 2) Surface/cross-sectional images of the MCF electrode and power outputs of BCFs

(A) Photographic images of bare cotton fiber (top) and the highly conductivite fiber electrode coated with metallic nanoparticles (bottom)

(B) Surface images of the cotton fibers coated with metallic nanoparticles

(C) Cross-sectional field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDS) mapping images of the metallic cotton fiber. They confirm that metallic nanoparticles are evenly distributed onto the inner surfaces of the electrode, and this promotes charge transfer through the cottone fiber electrode..

(D) The maximum power outputs of the MCF-BFCs in the form of a 120-MCF cathode (3.7 mW cm−2) and two MCF-BFCs in series (7.1 mW cm−2)