Porous translucent electrodes enhance current generation from photosynthetic biofilms

TL;DR

This study demonstrates that porous, microstructured electrodes significantly boost electrical current from photosynthetic bacteria, mainly due to increased surface area, with potential implications for bio-electrochemical applications.

Contribution

The paper introduces the use of nano- and micrometer-scale porosity in electrodes to enhance current generation from photosynthetic biofilms, highlighting the importance of surface area and microarchitecture.

Findings

Porous electrodes increase current by two orders of magnitude.

Microstructured architectures provide additional benefits with direct electron transfer.

Porosity mainly enhances performance through increased surface area.

Abstract

We tested the enhancement of electrical current generated from photosynthetically active bacteria by use of electrodes with porosity on the nano- and micrometer length-scale. For two cyanobacteria on structured indium-tin-oxide electrodes, current generation was increased by two orders of magnitude and the photo-response was substantially faster compared to non-porous anodes. These properties highlight porosity as an important design strategy for electrochemical bio-interfaces. The role of porosity on different length scales was studied systematically which revealed that the main performance enhancement was caused by the increased surface area of the electrodes. More complex microstructured architectures which spanned biofilms as translucent 3D scaffolds provided additional advantage in the presence of microbial direct electron transfer (DET). The absence of a clear DET contribution in both studied cyanobacteria, Synechocystis and Nostoc, raises questions about the role of conductive cellular components previously found in both organisms.