Stabilizing molecular catalysts on metal oxide surfaces using molecular layer deposition for efficient water oxidation†

Abstract

The stabilization of metal–oxide-bound molecular catalysts is essential for enhancing their lifetime and commercial viability in heterogeneous catalysis. This is particularly relevant in dye-sensitized photoelectrochemical cells (DSPECs), where the surface-bound chromophores and catalysts exhibit instability in aqueous environments, particularly at elevated pH levels. In this work, we have successfully employed molecular layer deposition (MLD) to stabilize ruthenium-based catalysts (RuCP(OH₂)²⁺, denoted as RuCat). The application of polyimide (PI) via MLD onto the porous nanoITO surface significantly improved the stabilization of RuCat molecules for water oxidation. Additionally, time-resolved photoluminescence (TRPL) spectroscopy and femtosecond transient absorption spectroscopy (fs-TAS) results indicated that the MLD-deposited PI effectively preserved the robust redox capacity of the photogenerated electron–hole pairs associated with the catalyst molecules, thereby facilitating more efficient charge transfer. This research presents a novel approach for stabilizing surface-bound small molecules, which may contribute to advancements in heterogeneous catalysis and enhance its commercial viability.