Upconversion Nanoparticles Expand the Photosynthetically Active Spectrum of Microalgae into the Near-Infrared for CO 2 Biofixation

fixation rate increased by 94.31%. Consequently, compared with the control group, the density of the microalgal biomass rose by 19.67%, while the light conversion efficiency increased by 34.99% to reach 8.4%. This work develops a biohybrid system that enhances NIR light harvesting and photosynthetic carbon fixation, elucidates the role of NIR photon upconversion in regulating photosynthetic electron transport and metabolism in microalgae, and thereby provides a pathway for efficient microalgal photosynthetic carbon capture.