Chapter 13 - Energy harvesting, charge, and mass transport considerations for reaction center-nanomaterial composites

Abstract

Combining proteins and abiotic substances such as electrodes and nanomaterials is as attractive as it is challenging. Photosynthetic reaction centers (RCs) convert light energy of a single photon to cause a charge separation resulting in an excited electron, typically with a high quantum yield, making them among the most attractive proteins to harness for energy capture. RCs from purple bacteria provide a unique combination of visible and near-infrared light utilization with long term stability. This chapter will consider not only RC structure and function, but also of RC density on the chosen electrode, the electrode material itself, as well as addressing overall efficiency and long-term stability. The overlap between multiple fields spanning biochemistry, biophysics, nano-material science, and chemical engineering inspired the authors to systematically review literature from these perspectives to highlight the interplay of photon energy reception, energy conversion, as well as electron and mass transport. Nanoparticles (NPs) similar in dimensions to natural antenna and RCs, that are all much shorter than the wavelength of light they interact with, provide a valuable insight into not only interfacing strategies, but also ease of synthesis and perhaps into RCs function, as well. Nanoparticle incorporation into plants is also reviewed. Multiple examples of common practices within the fields of electrochemistry, chemical preparation of biological, and nanomaterials, to include scale up challenges, are discussed. Past and current efforts in engineering of photovoltaic devices based on purple bacterial RCs are reviewed and compared based on current density in micro amps per square centimeter (µA cm−2). Lastly, several opportunities are identified for the future of reaction center-electrode interfacial design.