SiC nanoparticles promote CO2 fixation and biomass production of Chlorella sorokiniana via expanding the abilities of capturing and transmitting photons

Microalga-semiconductor hybrids for solar-to-biomass conversion which integrate microalgal photosynthesis with the efficient light capture of artificial semiconductors can significantly promote CO₂ fixation and productivity of microalgal cells. However, such pertinent studies are poor and the promoting mechanism is unclear yet. Silicon carbide nanoparticles (SiC NPs) have remarkable biocompatibility and photocatalytic ability. Here, to get insights into the promoting mechanism the hybrids were constructed by using SiC NPs and microalga Chlorella sorokiniana, and tested the cell growth, chlorophyll fluorescence, changes in extracellular morphology and structure, absorption spectroscopy and photo-electrochemistry. The results showed that in the hybrid systems with SiC NPs in 0-20 mg/L the cell growth, CO₂ fixating and biomass accumulation rate were promoted significantly, with 90 %, 49 % and 38 % increase in the maximum relative electron transport rates, maximal biomass and lipid yields, respectively, in the hybrid with 10 mg/L SiC NPs added. It suggested that SiC NPs can promote microalgal photosynthesis by transferring photogenerated electrons into the electron transport chain, expanding the capture of photoenergy and enhancing intracellular electron transport, rather than photoluminescence or photocatalytic CO₂ reduction products.