Silatrane Functional Rubds-Based Catalyst for Stabilized Heterogenized Water Oxidation

Dye-sensitized photoelectrochemical cells (DSPECs) for water splitting into hydrogen and oxygen represent a promising approach to storing solar energy in chemical bonds. The surface-immobilized catalyst plays a crucial role in DSPEC performance. However, the water oxidation process requires substantial energy to break OH bonds, resulting in sluggish reaction kinetics. Consequently, depositing highly efficient and durable molecular water oxidation catalysts onto metal oxide surfaces presents a significant research challenge. Here, this study introduces a ruthenium-based pyridine water oxidation complex featuring a bds²⁻ ligand (bds²⁻ = 2,2′-bipyridine-6,6′-disulfonate) and a silatrane anchoring group for stable attachment to metal oxide semiconductors, forming a robust single-site heterogeneous catalyst. In pH 7 aqueous solution, the resulting Ru-bds (F-doped tin oxide/nanoATO/2C-bds). catalyst achieves a stable current density of 0.89 mA cm⁻² and a turnover frequency of 5.1 s⁻¹ over a 2 h test under an applied bias of 1.6 V versus normal hydrogen electrode. A variety of Ru-oxo intermediates generated during water oxidation are analyzed using in situ ultraviolet-visible, Raman, and infrared spectroscopies. These techniques provide data that support the proposed mechanism of heterogeneous water oxidation over Ru-bds catalysts. This work presents a streamlined strategy for designing stable, single-site heterogeneous catalysts for efficient solar-driven water oxidation.