Designing TiO Nanotubular Arrays with Au-CoO Core-Shell Nanoparticles for Enhanced Photoelectrochemical Methanol and Lignin Oxidation.

One-dimensional (1D) ordered TiO nanotubes exhibit exceptional charge transfer capabilities, making them suitable candidates for constructing visible-light-active photoanodes in selective PEC oxidation reactions. Herein, we employed a facile and easily scalable electrochemical method to fabricate Au-CoO-deposited ordered TiO nanotubular array photoanodes. The improved visible light absorption capacity of TiO-Au-CoO, with unhampered 1D channels and the controlled integration of Au between TiO and CoO, along with their synergistic interaction, have been identified as the most promising strategy for enhanced PEC performance, as evidenced by an IPCE of 3.7% at 450 nm. Furthermore, the robust interfacial charge transfer pathway from CoO to the TiO surface via the Au mediator promotes the migration of photogenerated electrons and enables the accumulation of holes on the surface of CoO. These holes are then efficiently utilized by oxidants such as methanol or lignin to generate value-added products, highlighting the potential of this system for advanced PEC applications.