Miniature direct electron transfer based sulphite/oxygen enzymatic fuel cells

Area of Science:

• Bioelectrochemistry
• Enzyme-based biosensors
• Renewable energy technologies

Background:

• Direct electron transfer (DET) biofuel cells offer sustainable energy solutions.
• Sulfite oxidase (SOx) and bilirubin oxidase (BOx) are key enzymes for biofuel cell applications.
• Nanostructured electrodes enhance enzyme immobilization and electron transfer efficiency.

Purpose of the Study:

• To develop a direct electron transfer (DET) based sulfite/oxygen biofuel cell.
• To utilize human sulphite oxidase (hSOx) and Myrothecium verrucaria bilirubin oxidase (MvBOx) for bioelectrocatalysis.
• To achieve high power densities and efficient energy conversion.

Main Methods:

• Fabrication of nanostructured gold electrodes modified with 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) and polyethylene imine.
• Immobilization of hSOx onto the bioanode for sulfite oxidation.
• Immobilization of MvBOx onto gold nanoparticles for oxygen reduction at the biocathode.
• Integration of bioanode and biocathode into a DET-based biofuel cell.

Main Results:

• High surface loading of electroactive hSOx achieved on the modified electrode.
• Anodic bioelectrocatalytic currents generated with an onset potential of 0.05V vs. NHE in the presence of sulfite.
• Cathodic oxygen reduction initiated at 0.71V vs. NHE by MvBOx.
• Power densities of 8 and 1 μWcm⁻² achieved at 0.15V and 0.45V cell voltages, respectively.

Conclusions:

• The developed biofuel cell demonstrates efficient sulfite and oxygen conversion using immobilized enzymes.
• The DET mechanism and nanostructured electrodes contribute to high performance.
• This work highlights the potential of enzyme-based biofuel cells for sustainable energy generation.