The sustainable synthesis of fuels and chemicals using sunlight as driving force and simple readily available feedstock such as H₂O and waste CO₂ provides a potential feasible pathway to mitigate increasing CO₂ emissions and transitioning toward a greener chemical industry. In this context, natural photosynthesis is a source of inspiration and has led to the evolving and multidisciplinary field of artificial photosynthesis (AP).^[1-4]

In this regard, when designing bioinspired photocatalytic platforms for AP, the role of natural membranes -in the compartmentalization and separation of the redox half reactions involved in natural photosynthesis-, is sometimes overlooked. Our research group is currently working towards studying this key structural factor of natural photosynthesis.^[4] We are working in the development of polymeric microphotoreactors functionalized with (photo)catalysts to produce solar fuels and chemicals. Our ultimate goal is to drive the electrons from the oxidation of water to the reduction of CO₂-to-Carbon-based fuels and chemicals in aqueous media using solar energy as driving force.^[5] As such, we have developed a novel family of asymmetric porphyrin and phthalocyanine complexes bearing Co, Ni, and Fe as 1^st row transition metal centers for photocatalytic CO₂ reduction in combination with Ir-, Cu-based photosensitizers and organic dyes, under visible light irradiation (447 nm) in aqueous-organic mixtures in presence of a sacrificial electron donor.^[5-6] The Co and Fe phthalocyanine complexes show a remarkable photocatalytic activity and selectivity for photocatalytic CO₂ reduction to CO (up to 2600 TON CO with 88% selectivity) in homogeneous conditions, even with 10% of water. In contrast, the porphyrin complexes show remarkable activity and selectivity for methane production in organic mixtures. Moreover, to further explore the applicability and increase the stability of these systems, we have anchored them onto the membrane of polymeric vesicles, developing the first polymersome for compartmentalized photocatalytic CO₂ reduction.^[6] The effect of anchoring and the nature of the photosensitizer used allows to tune the selectivity of the photocatalytic reaction to obtain only CO₂ reduction derived products in water, suppressing the normally competing hydrogen evolution reaction. Mechanistic studies are ongoing to rationalize these differences in reactivity between homogeneous and heterogenized systems.

References

[1] Das Neves Gomes C., et al. Angew. Chem. Int. Ed. 2012, 51, 187-190.

[2] Boutin E., et al. Chem. Soc. Rev. 2020, 49, 5772-5809.

[3] Pannwitz A., et al. Chem. Soc. Rev. 2021, 50, 4833-4855.

[4] L. Velasco-Garcia, C. Casadevall. Commun. Chem. 2023, 6:263

[5] E. J. Espinoza-Suárez, A. Bekaliyev, A. Vital-Grappin, L. Velasco-Garcia, L. Subirats-Valls, C. Casadevall. Manuscript under revisions.                                                                            

[6] L. Velasco-Garcia, K. Nassif, A. Bekaliyev, E. J. Espinoza-Suarez, C. Casadevall. Manuscript in preparation.