Ruthenium Assemblies for CO2 Reduction and H2 Generation: Time Resolved Infrared Spectroscopy, Spectroelectrochemistry and a Photocatalysis Study in Solution and on NiO

• Published in: Frontiers in chemistry Vol. 9; p. 795877
• Main Authors: Cerpentier, Florian J. R., Karlsson, Joshua, Lalrempuia, Ralte, Brandon, Michael P., Sazanovich, Igor V., Greetham, Gregory M., Gibson, Elizabeth A., Pryce, Mary T.
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 24.12.2021
• Subjects: Chemistry; CO2; hydrogen; photocatalysis; ruthenium assemblies; spectroelectrochemistry; time resolved spectroscopy
• ISSN: 2296-2646; 2296-2646
• DOI: 10.3389/fchem.2021.795877

Two novel supramolecular complexes RuRe ([Ru(dceb) 2 (bpt)Re(CO) 3 Cl](PF 6 )) and RuPt ([Ru(dceb) 2 (bpt)PtI(H 2 O)](PF 6 ) 2 ) [dceb = diethyl(2,2′-bipyridine)-4,4′-dicarboxylate, bpt = 3,5-di(pyridine-2-yl)-1,2,4-triazolate] were synthesized as new catalysts for photocatalytic CO 2 reduction and H 2 evolution, respectively. The influence of the catalytic metal for successful catalysis in solution and on a NiO semiconductor was examined. IR-active handles in the form of carbonyl groups on the peripheral ligand on the photosensitiser were used to study the excited states populated, as well as the one-electron reduced intermediate species using infrared and UV-Vis spectroelectrochemistry, and time resolved infrared spectroscopy. Inclusion of ethyl-ester moieties led to a reduction in the LUMO energies on the peripheral bipyridine ligand, resulting in localization of the 3 MLCT excited state on these peripheral ligands following excitation. RuPt generated hydrogen in solution and when immobilized on NiO in a photoelectrochemical (PEC) cell. RuRe was inactive as a CO 2 reduction catalyst in solution, and produced only trace amounts of CO when the photocatalyst was immobilized on NiO in a PEC cell saturated with CO 2 .