Rational design of porous structures via molecular layer deposition as an effective stabilizer for enhancing Pt ORR performance

Abstract

Pt-based catalysts are widely applied in fuel cells as key components of both anode and cathode. However, commercial Pt/C catalysts with Pt nanoparticles dispersed on carbon support exhibit poor durability due to the Ostwald ripening effect, detachment and agglomeration of Pt nanoparticles during fuel cell operation. Herein, we demonstrate for the first time the application of molecular layer deposition (MLD) to stabilize Pt catalysts. By atomic layer deposition (ALD) of Pt particles on MLD-derived interlayer, the Pt catalysts show significantly enhanced oxygen reduction reaction (ORR) activity and durability compared to that without the MLD interlayer. The MLD-derived surfaces with enriched pores are helpful for anchoring the Pt nanoparticles and to avoid agglomeration or detachment from the surface sites. In addition, X-ray adsorption spectroscopy (XAS) results show that the deposition of Pt on the MLD-derived interlayer caused the electron transfer from Pt to substrates, which results in a decrease in the number of electrons in the d orbital of Pt. In addition, the extended X-ray absorption fine structure (EXAFS) result indicates that PtPt bond distance is shortened by the deposition on the MLD-derived NCNT, which leads to the enhanced activity of Pt catalysts. This work provided a novel route for stabilizing Pt catalysts through MLD technique.