Realizing UV driven microalgae photosynthesis to bio-fix CO2 by spectrum conversion

Microalgae, as efficient photosynthetic autotrophs, hold significant potential for carbon sequestration. However, their photosynthesis is constrained by the selective use of the solar spectrum. To enhance the utilization of natural light energy, a dual functional substrate with ultraviolet (UV) light conversion and microalgae biofilm support was proposed by coating a rare earth complexes phosphor agent onto transparent acrylic in this study. By doing this, UV light could directly drive microalgae biofilm photosynthesis by converting it to red light, resulting in a maximum 2.81 times increase in the carbon fixation rate. The UV conversion substrate increased the electron transport rate of microalgal photosystem II by 58.08%, effectively enhancing the photosynthetic rate and oxygen release, promoting the formation of a porous biofilm structure, and strengthening the material transfer within the biofilm. Additionally, reactive oxygen species (ROS) can cause oxidative stress, affecting cell growth and metabolic activity. With the use of the UV conversion substrate, the levels of ROS and malondialdehyde (MDA) in microalgae decreased by 84.56% and 42.35%, respectively. Consequently, UV-induced damage to microalgae cells was reduced, leading to a 52.52% increase in the photosynthesis rate and achieving UV driven photosynthetic carbon sequestration. This study demonstrated the UV conversion substrate's effectiveness in reducing UVinduced damage in microalgae and enhancing photosystem activity, showing significant potential for carbon fixation within microalgal biofilms.