Ionic liquid functionalised nanoceria significantly enhances photosynthetic CO2 sequestration

The threat posed by increasing CO 2 concentrations in the atmosphere requires innovative carbon sequestration technologies. Photosynthetic CO 2 sequestration by plants is a sustainable pathway, but its full potential is limited due to CO 2 diffusion and abiotic stress in the plant. Engineered nanomaterials such as nanoceria (CeO 2 ) can increase the activity of chloroplasts due to their photocatalytic activity and thus stimulate photosynthetic processes. In the present study, the development of a new nanoformulation of CeO 2 whose surface was functionalised with an ionic liquid (IL), cholinium ascorbate ([Cho][Asc]) was investigated to enhance photosynthetic CO 2 fixation in tobacco plants. Compared to CeO 2 and IL, the CeO 2 + [Cho][Asc] nanoformulation significantly improved plant growth, biomass yield, photosynthetic rate and CO 2 fixation. Compared to the control, plants treated with CeO 2 + 50 mM [Cho][Asc] showed ∼2-fold higher photosynthetic rate and a 198 % increase in dry biomass accumulation. The maximum quantum efficiency of photosystem II (F v /F m ) results were consistent with the observed photosynthetic rate. Application of CeO 2 + 50 mM [Cho][Asc] resulted in CO 2 sequestration of 3.02 t/hectare, which is 80–110 % higher than CeO 2 and IL applied separately, and 279 % higher than the control. This improvement in photosynthetic CO 2 fixation was achieved without compromising tobacco seed yield, as foliar application of CeO 2 + 50 mM [Cho][Asc] resulted in significantly higher seed yield than in control plants. Overall, this study provides insights into the effects of IL-modified CeO 2 -based nanoformulations on plant growth and CO 2 fixation, contributing to sustainable agriculture and mitigating climate change. A simple strategy for enhancing photosynthetic rate and CO 2 sequestration in tobacco plant using [Cho][Asc] IL-modified nanoceria-based nanoformulation is demonstrated. • A new nanoformulation by surface engineering of nanoceria with [Cho][Asc] IL was developed. • Treatment of IL+CeO 2 resulted a 2-fold higher biomass production than control in tobacco. • IL+CeO 2 treated plants showed a 2.8-fold increase in photosynthetic CO 2 sequestration. • F v /F m results indicate a cooperative effect of IL-modified CeO 2 in the photosynthetic response.