Synergistic enhancement of the hydrogen evolution reaction by bimetallic Pt–Ru nanoparticles supported on a carbon xerogel

Abstract

Pt–Ru alloys have shown promising catalytic activity toward the hydrogen evolution reaction (HER) in acidic media; however, their stability remains a critical challenge due to the oxidation and dissolution of Ru species in 0.5 M H₂SO₄. Herein, the synthesis and comparative assessment of a series of electrocatalysts based on a carbon xerogel loaded with platinum and ruthenium, Pt–Ru, specifically a pure carbon xerogel (CX), 5 wt% platinum-loaded CX (Pt5/CX), 5 wt% platinum and 2.5 wt% ruthenium co-loaded CX (Pt5:Ru2.5/CX), and 5 wt% platinum and 5 wt% ruthenium co-loaded CX (Pt5:Ru5/CX) were evaluated for the HER. The carbon xerogel served as a high-surface-area, porous, and conductive substrate, promoting uniform distribution of the metallic nanoparticles, mitigating Ru leaching, and improving charge transfer during the HER. The Pt5:Ru2.5/CX composite displayed superior catalytic activity, achieving the lowest overpotential (39 mV, at 10 mA cm⁻²), minimal Tafel slope (29 mV dec⁻¹), and maximal double-layer capacitance (C_dl of 52.68 mF cm⁻²) in 0.5 M H₂SO₄. The improved HER activity is ascribed to the synergistic interaction between Pt and Ru, together with reduced charge transfer resistance (R_ct, 0.4 Ω) and active site accessibility afforded by the carbon xerogel matrix.