Engineering Pt single atom catalysts on titania nanotubes via the photo/ electrochemical pathway for a selective ammonia oxidation reaction

This study presents the synthesis of a self-organized TiO2 nanotube (TNT) array via anodization of Ti foil, followed by Pt deposition using electrochemical (ED), photoelectrochemical (PED), and combined ED/PED techniques without a metal precursor in the electrolyte. Structural analysis confirmed anatase TiO2 nanotubes with single-atom Pt in Pt/TNTED and Pt/TNTED/PED, while Pt clusters formed in Pt/TNTPED. The Pt/TNTED/PED system showed superior Pt-TiO2 electronic interactions (XPS and CO-IR) and achieved the best photoelectrochemical performance, with enhanced photocurrent density, reduced overpotential for ammonia oxidation, and high stability. It also exhibited excellent hydrogen and nitrogen evolution rates, with optimized NH4OH concentration (0.1 M) further boosting performance. This work highlights the potential of Pt-deposited TNT, particularly Pt/ TNT ED/PED , for efficient photoelectrochemical ammonia oxidation and hydrogen production, offering valuable insights for catalyst optimization.