Experimental and Theoretical Insights into Enhanced Hydrogen Evolution over PtCo Nanoalloys Anchored on a Nitrogen-Doped Carbon Matrix

Abstract

The identification of synergistic effect of Pt-based alloys on hydrogen evolution reaction (HER) requires a combination of experimental studies and theoretical calculations. Here, we present the construction of uniform PtCo nanoparticles grown on N-doped carbon frameworks via pyrolyzing Pt and Co ions adsorbed polyaniline, whereby the nanostructure of the nanoalloys can be effectively tuned by controlling the calcination temperature. As-prepared PtCo@NC-900 shows the optimal HER performance in 0.5 M H₂SO₄, resulting in a high mass activity of 4.31 A mg_Pt^-1 and excellent operation durability, which far exceeds that of commercial 20 wt % Pt/C (0.30 A mg_Pt^-1). Density functional theory calculations further reveal that the improved HER activity on PtCo(111) is originated from the strong electronic interaction between Pt and Co with favorable electron transfer, allowing for a more suitable binding strength for hydrogen (i.e., Δ<i>G</i>_*H = -0.164 eV) compared with that of pristine Pt(111) (-0.287 eV).