Sequence-Controlled\nElectrochemical Immobilization\nof Catalyst-Photosensitizer Oligomers for Tuning Photoelectrochemical\nBehaviors

Immobilizing catalysts and photosensitizers on an electrode\nsurface\nis crucial in interfacial energy conversion. However, their combination\nfor optimizing catalytic performance is an unpredictable challenge.\nHerein, we report that catalyst and photosensitizer monomers are selectively\ngrafted one-by-one addition onto the electrode surface by interfacial\nelectrosynthesis to achieve composition and sequence-controlled oligomer\nphotoelectrocatalytic monolayers. This electrosynthesis relies on\nthe oxidative coupling reaction of carbazole and the reductive coupling\nreaction of vinyl on the catalyst and photosensitizer monomers, and\nit initiates on self-assembled monolayers and propagates with alternating\npositive and negative potentials. Each addition and completion of\nthe target monomer can be quantitatively identified and monitored\nby optical and electrical responses and their linear coefficients\nas a function of reaction steps. The resulting composition and sequence-controlled\nmonolayers exhibit tuning electrocatalytic behaviors including water\nsplitting and CO<sub>2</sub> reduction, indicating an efficient way\nto optimize the electro- and photocatalytic functions and performance\nof molecular materials.