Optimized Pt Single Atom Harvesting on TiO<sub>2</sub> Nanotubes—Towards a Most Efficient Photocatalyst
Zhenni Wu, Imgon Hwang, Gihoon Cha, Shanshan Qin, Ondřej Tomanec, Zdeňěk Baďura, Štěpán Kment, Radek Zbořil, Patrik Schmuki
Abstract
Abstract In the present work the authors show that anodic TiO 2 nanotubes (NT) show excellent harvesting properties for Pt single atoms (Pt SAs) from highly dilute Pt solutions. The tube walls of anodic nanotubes, after adequate annealing to anatase, provide ample of suitable trapping sites—that is, surface Ti 3+ ‐ O v ( O v : oxygen vacancy) defects that are highly effective to extract and accumulate Pt in the form of SAs. A saturated (maximized) SA density can be achieved by an overnight immersion of a TiO 2 NT layer to a H 2 PtCl 6 solution with a concentration that is as low as 0.01 m m Pt. Such TiO 2 NTs with surface trapped Pt SAs provide a maximized high activity for photocatalytic H 2 generation (reaching a turnover frequency (TOF) of 1.24 × 10 6 h −1 at a density of 1.4 × 10 5 Pt atoms µm −2 )—a higher loading with Pt nanoparticles does not further increase the photocatalytic activity. Overall, these findings show that anodic TiO 2 nanotubes provide a remarkable substrate for Pt extraction and recovery from very dilute solutions that directly results in a highly efficient photocatalyst, fabricated by a simple immersion technique.