Designing TiO2 Nanotubular Arrays with Au-CoOx Core-Shell Nanoparticles for Enhanced Photoelectrochemical Methanol and Lignin Oxidation.

One-dimensional (1D) ordered TiO2 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-CoOx-deposited ordered TiO2 nanotubular array photoanodes. The improved visible light absorption capacity of TiO2-Au-CoOx, with unhampered 1D channels and the controlled integration of Au between TiO2 and CoOx, 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 CoOx to the TiO2 surface via the Au mediator promotes the migration of photogenerated electrons and enables the accumulation of holes on the surface of CoOx. 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.