Graphene Oxide–Enamino-Xanthene Charge-Transfer Hybrids as High-Performance Sensitizing Interfaces for TiO ₂ Photoanodes

Hybrid materials that combine visible-light absorption with efficient charge separation across interfaces are essential for advancing photoelectrochemical (PEC) energy conversion technologies. In this study, we report the synthesis of charge-transfer hybrids composed of graphene oxide (GO) and enamino-xanthene (NH₂-X) dyes, prepared via a simple and sustainable liquid-phase mixing approach. Spectroscopic analyses reveal strong interface interactions between GO and NH₂-X, leading to suppressed fluorescence and altered electronic transitions, consistent with ground-state charge-transfer processes. When interfaced with TiO₂ as a sensitizing layer, the resulting photoanodes deliver a 3.5-fold enhancement in photocurrent, faster saturation kinetics, and improved photopotential generation under visible-light illumination. Electrochemical impedance spectroscopy confirms reduced interface resistance and enhanced charge carrier mobility at both solid-solid and solid-liquid interfaces. The synergistic integration of GO and NH₂-X establishes a high-performance sensitizing interface for TiO₂ photoanodes, offering a scalable and environmentally benign route toward advanced PEC applications.