Encapsulation of molecular catalysts inside polymeric scaffolds has gained substantial attention over the recent years, as it provides a path towards generating systems which mimic the metallo-enzyme morphology as “synthetic hydrogenases”. By conjugating the “active sites” within macromolecular scaffolds, i.e. polymers, an efficient second sphere of coordination with enhanced stability and enzyme-like morphologies and properties is then created. In the context of solar fuels research and chemical energy conversion, this approach has been found to improve both rates and energy efficiency of the catalysis. As proof of concept, we have focused on the encapsulation of a biomimetic azadithiolate (–CH2NHCH2S–, adt2–) bridged {Fe2(μ-S2)(CO)6} based active site (“[2Fe2S]”), inspired by the catalytic cofactor of [FeFe] hydrogenases, within a synthetic pH-sensitive polymeric scaffold bearing hydrophobic stacking group for heterogenization onto Carbon NanoTubes. Such metallo-enzymes were found to be active for electrochemical H2production in neutral aqueous media.[1], [2], [3]

This concept was also extended to the encapsulation of molecular catalyst for CO2 reduction[4],[5],[6] and more recently with water oxidation catalysts. A similar approach with the aim to modify the sphere of coordination of metallic benchmarked electrode demonstrated the impact of a thin polymeric layer on the CO2 reduction efficiency and selectivity.[7], [8]

However, system performance still needs to be improved to reach technologically relevant currents and stability, parameters that are heavily influenced by the nature of the incorporated molecular catalyst or the design of the electrode.

[1] A. Zamader, B. Reuillard, P. Marcasuzaa, A. Bousquet, L. Billon, J. Espi Gallart, G. Berggren, V. Artero ACS Catalysis, 2023, 13, 1246–1256.

[2] A. Zamader, B. Reuillard, J. Pécaut, L. Billon, A. Bousquet, G. Berggren, V. Artero Chem. Eur. J. 2022, e202202260.

[3] A. Zamader, B. Reuillard, L. Billon, G. Berggren, V. Artero Sustainable Energy & Fuels, 2023, 7, 4967-4976.

[4] D. Grammatico, H.N. Tran, Y. Li, S. Pugliese, L. Billon, B-LSu, M. Fontecave ChemSusChem, 2020, 13, 6418-6425.

[5] D. Grammatico, P. Marcasuzaa A. Viterisi, A. Bousquet, B-L. Su, L. Billon ChemComm, 2023, 59, 2279 – 2282.

[6] D. Grammatico, A.J. Bagnall, L. Riccardi, M. Fontecave, B.L. Su, L. Billon, Angewandte Chemie, 2022, 61, e2022063.

[7] A. Fortunati, S. Hernandez, A. Viterisi, P. Marcasuzaa, L. billon European Patent, 2023, EP23306210.8.

[8] F. Vieira, P. Marcasuzaa, L. Billon, A. Viterisi, E. Palomares to be submitted asap, 2024.