Improving the HER Activity and Stability of Pt Nanoparticles by Titanium Oxynitride Support

Water electrolysis powered by renewables is regarded as the feasible route for the production of hydrogen, obtained at the cathode side through electrochemical hydrogen evolution reaction (HER). Herein, we present a rational strategy to improve the overall HER catalytic performance of Pt, which is known as the best monometallic catalyst for this reaction, by supporting it on a conductive titanium oxynitride (TiONx) dispersed over reduced graphene oxide nanoribbons. Character-ization of the Pt/TiONx composite revealed the presence of small Pt particles with diameters between 2 and 3 nm, which are well dispersed over the TiONx support. The Pt/TiONx nanocomposite exhibited improved HER activity and stabi l i t y with respect to the Pt/C benchmark in an acid electrolyte, which was ascribed to the strong metal-support interaction (SMSI) triggered between the TiONx support and grafted Pt nanoparticles. SMSI between TiONx and Pt was evidenced by X-ray photoelectron spectroscopy (XPS) through a shif t of the binding energies of the characteristic Pt 4f photoelectron lines with respect to Pt/C. Density functional theory (DFT) calculations confirmed the strong interaction between Pt nanoparticles and the TiONx support. This strong interaction improves the stabi l i t y of Pt nanoparticles and weakens the binding of chemisorbed H atoms thereon. Both of these effects may result in enhanced HER activity.

Automated summary

In this study, the overall catalytic performance of Pt, the best monometallic catalyst for the hydrogen evolution reaction (HER), was improved by supporting it on conductive titanium oxynitride (TiONx) dispersed over reduced graphene oxide nanoribbons. The strong metal-support interaction (SMSI) between TiONx and Pt was identified as the cause of the improved HER activity and stability.