Efficient and Robust Hybrid Molecular Photoanodes for Water Oxidation at Neutral pH Based on Ru Complexes Covalently Bonded to Polymeric Carbon Nitride

Light-induced water splitting (hν-WS) represents a promising strategy for the sustainable generation of green hydrogen. In particular, the photoelectrochemical water oxidation (WO) reaction remains a critical step due to its kinetic and thermodynamic demands. Heterostructures comprising water oxidation catalysts (WOCs) integrated with photoactive materials, such as polymeric carbon nitride (CN), have demonstrated potential for enhancing the performance owing to their favorable energetics, cost-effectiveness, and device simplicity. However, intrinsic limitations of CN, including poor charge separation and electron transfer properties, limited activity, and stability under near-neutral conditions, hinder its practical application. To address these challenges, we report the covalent functionalization of CN with a Ru-based molecular WOC, yielding hybrid photoelectrode CNTM@Ru. The photoelectrocatalytic activity of CNTM@Ru toward WO was evaluated under simulated solar irradiation (1 sun), displaying a sustained photocurrent density of ∼480 μA cm–2 at 1.23 V vs RHE over 15 h (TON > 2000) at neutral pH. Comprehensive photophysical analyses revealed enhanced charge separation and interfacial charge-transfer dynamics, corroborating the synergistic role of the covalently anchored molecular catalyst in facilitating multielectron transfer steps and enabling efficient water oxidation catalysis.