High-Density Dual-Structure Single-Atom Pt Electrocatalyst for Efficient Hydrogen Evolution and Multimodal Sensing

Herein, we report a high-density dual-structure single-atom
catalyst
(SAC) by creating a large number of vacancies of O and Ti in two-dimensional
(2D) Ti3C2 to immobilize Pt atoms (SA Pt-Ti3C2). The SA Pt-Ti3C2 showed
excellent performance toward the pH-universal electrochemical hydrogen
evolution reaction (HER) and multimodal sensing. For HER catalysis,
compared to the commercial 20 wt % Pt/C, the Pt mass activities of
SA Pt-Ti3C2 at the overpotentials of ∼30
and 110 mV in acid and alkaline media are 45 and 34 times higher,
respectively. More importantly, during the alkaline HER process, an
interesting synergetic effect between Pt-C and Pt-Ti sites that dominated
the Volmer and Heyrovsky steps, respectively, was revealed. Moreover,
the SA Pt-Ti3C2 catalyst exhibited high sensitivity
(0.62–2.65 μA μM–1) and fast
response properties for the multimodal identifications of ascorbic
acid, dopamine, uric acid, and nitric oxide under the assistance of
machine learning.