Solar Photothermal Electrodes for Highly Efficient Microbial Energy Harvesting at Low Ambient Temperatures

Temperature is an important parameter for the performance of bioelectrochemical systems (BESs). Energy-intensive bulk water heating has been usually employed to maintain a desired temperature for the BESs. This study concerns a proof-of-concept of a light-to-heat photothermal electrode for solar heating of a local electroactive biofilm in a BES for efficient microbial energy harvesting at low temperatures as a replacement for bulk water heating approaches. The photothermal electrode was prepared by coating Ti₃ C₂ T_x MXene sunlight absorber onto carbon felt. The as-prepared photothermal electrode could efficiently raise the local temperature of the bioelectrode to approximately 30 °C from low bulk water temperatures (i.e., 10, 15, and 20 °C) under simulated sunlight illumination. As a result, highly efficient microbial energy could be harvested from the low-temperature BES equipped with a photothermal electrode without bulk water heating. This study represents a new avenue for the design and fabrication of electrodes for temperature-sensitive electrochemical and biological systems.