Modulating the electronic structure of PtFe alloys supported on carbon onions for enhancing pH-universal hydrogen evolution reaction

Abstract

Optimizing platinum-based catalysts for hydrogen generation via water electrolysis in pH-universal electrolytes is significant, and modulating the electronic structure is a viable strategy. Herein, platinum-iron (Pt–Fe) alloys with varying composition supported on carbon onions (CNOs) were successfully synthesized: PtxFey@CNOs (x, y = 0.6, 0.4; 0.5, 0.5; 0.4, 0.6). Beneficial from the precisely modulated crystal plane spacing and electronic structure by tuning the Pt/Fe composition, in general pH electrolytes, PtxFey@CNOs display outstanding hydrogen evolution reaction (HER) activity. The as-prepared Pt0.5Fe0.5@CNOs shows low overpotentials (η10) of 11, 30, and 19 mV at −10 mA cm−2 in 0.5 M H2SO4, 1.0 M phosphate-buffered saline (PBS), and 1.0 M KOH electrolyte, respectively. Compared to commercial Pt/C, it displays enduring stability up to 24 h. Density functional theory (DFT) calculations indicate that Pt0.5Fe0.5@CNOs displays the lowest H* Gibbs free energy (ΔGH*) and water dissociation energy values, due to the suitable proton adsorption and H2O dissociation processes offered by its electronic structure. Moreover, it is proven that the support with better wettability has a positive effect on HER performance of the catalyst. The optimal electronic structure and improved wettability provide novel insight into developing a Pt-based HER pH-universal catalyst.