Photoanode nanostructure design and electron transport prediction

Abstract This paper employs the density functional theory (DFT) to evaluate the effect of different photoanode designs on the electron transport in photoelectrochemical biofuel cells. The electron transfer between different nano structure photoanodes, various sensitizers, and bio-electrolytes are analyzed via the computational quantum mechanics technique. The photoanode employs zinc oxide semiconductors, which have a great potential in cost reduction, higher dye absorption ability and easy production in the industry. Several molecular structure models, such as ZnO nanowires and ZnO nanotubes, with some novel biological pigments have been set up using minimum energy principles. Simulation results reveal that ZnO nanotubes possess lower conduction bands which are potentially easier to transfer electrons from biopigments (e.g., chlorin, chlorophyll a and cyanidin) to the anode to enhance the cell efficiency. In conclusion, the first-principles technique employing the density functional theory is able to predict the multi-electron transport phenomena which cannot be visualized through measurements. It can also be used to screen different design ideas for future green energy applications.