Designing TiO<sub>2</sub> Nanotubular Arrays with\nAu-CoO<sub><i>x</i></sub> Core–Shell Nanoparticles\nfor Enhanced Photoelectrochemical Methanol and Lignin Oxidation

One-dimensional (1D) ordered TiO<sub>2</sub> nanotubes\nexhibit\nexceptional charge transfer capabilities, making them suitable candidates\nfor constructing visible-light-active photoanodes in selective PEC\noxidation reactions. Herein, we employed a facile and easily scalable\nelectrochemical method to fabricate Au-CoO<sub><i>x</i></sub>-deposited ordered TiO<sub>2</sub> nanotubular array photoanodes.\nThe improved visible light absorption capacity of TiO<sub>2</sub>-Au-CoO<sub><i>x</i></sub>, with unhampered 1D channels and the controlled\nintegration of Au between TiO<sub>2</sub> and CoO<sub><i>x</i></sub>, along with their synergistic interaction, have been identified\nas the most promising strategy for enhanced PEC performance, as evidenced\nby an IPCE of 3.7% at 450 nm. Furthermore, the robust interfacial\ncharge transfer pathway from CoO<sub><i>x</i></sub> to the\nTiO<sub>2</sub> surface via the Au mediator promotes the migration\nof photogenerated electrons and enables the accumulation of holes\non the surface of CoO<sub><i>x</i></sub>. These holes are\nthen efficiently utilized by oxidants such as methanol or lignin to\ngenerate value-added products, highlighting the potential of this\nsystem for advanced PEC applications.