Single microbe photoelectrochemical device using scanning electrochemical microscopy

Abstract

Cyanobacteria are known for their efficient oxygenic photosynthesis, capturing solar energy to produce oxygen and organic compounds under various light conditions. In this work, we employed Synechocystis pevalekii cyanobacteria in a DSSC-based device and studied their photoelectrochemical (PEC) properties. The genome-scale metabolic model was simulated under dark and light conditions using MATLAB 2020b's COBRA Toolbox (Gurobi optimizer) to understand the light driven reactions. Guided by these simulations, the PEC devices were made in two different configurations, wherein one, the microbes are free-floating and in the second, they are anchored onto an anode as biofilm. The role of concentration of microbes, their age, conditioning and nutrient media on PEC performance is analysed. Finally, the photocurrent response of a single microbe on an agar-based biofilm was studied with a scanning electrochemical microscope (SECM) using a 1 μm Pt-tip as the working electrode, under both dark and light conditions. This single microbial device serves as a benchmark to identify or calculate the maximum possible PEC performance from a bulk microbial device.