In situ Pt single-atom trapping on TiO2 nanotubes via ultrasonication: a one-pot approach to produce active electrodes for electrocatalytic H2 evolution

Abstract

In the present study, we demonstrate a straightforward sonochemical approach for in situ defect formation and Pt single-atoms (SAs) decoration of anodic TiO₂ nanotubes (TNTs). The sonication of the TNTs in an ultra-low Pt concentration solution under optimum parameters leads to simultaneous high-energy defect formation and Pt SAs trapping. As a result, the number of defects and Pt loading can be controlled by sonication time. Such anodic TNTs decorated with Pt SAs (0.44 at% Pt) provide a highly active electrode with comparable performance to conventional 20 wt% Pt/C (≈8 at% Pt) electrodes for electrocatalytic H₂ generation. The Pt SAs decorated TNTs yield extraordinary performance as an electrode for electrocatalytic H₂ generation as measured by a low onset potential of −20 mV in acidic media. Additionally, the overpotential of electrocatalytic H₂ generation at the standard −10 mA cm⁻² exchange current density decreased almost three and four times for the sonicated anatase tubes decorated with Pt SAs in comparison to the anodic layers dipped in Pt precursor and pristine anatase, respectively. The SAs decoration strategies described herein offer a route to lower noble metal catalyst loading while achieving highly efficient electrodes for electrocatalytic applications.