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

Abstract

One-dimensional (1D) ordered TiO 2 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 x -deposited ordered TiO 2 nanotubular array photoanodes. The improved visible light absorption capacity of TiO 2 -Au-CoO x , with unhampered 1D channels and the controlled integration of Au between TiO 2 and CoO x , 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 x to the TiO 2 surface via the Au mediator promotes the migration of photogenerated electrons and enables the accumulation of holes on the surface of CoO x . 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.