Engineering the Near‐Surface of PtRu₃ Nanoparticles to Improve Hydrogen Oxidation Activity in Alkaline Electrolyte

Abstract

Tailoring the near‐surface composition of Pt‐based alloy can optimize the surface chemical properties of a nanocatalyst and further improve the sluggish H2 electrooxidation performance in an alkaline electrolyte. However, the construction of alloy nanomaterials with a precise near‐surface composition and smaller particle size still needs to overcome huge obstacles. Herein, ultra‐small PtRu3 binary nanoparticles (<2 nm) evenly distributed on porous carbon (PtRu3/PC), with different near‐surface atomic compositions (Pt‐increased and Ru‐increased), are successfully synthesized. XPS characterizations and electrochemical test confirm the transformation of a near‐surface atomic composition after annealing PtRu3/PC‐300 alloy; when annealing in CO atmosphere, forming the Pt‐increased near‐surface structure (500 °C), while the Ru‐increased near‐surface structure appears in an Ar heat treatment process (700 °C). Furthermore, three PtRu3/PC nanocatalysts all weaken the hydrogen binding strength relative to the Pt/PC. Remarkably, the Ru‐increased nanocatalyst exhibits up to 38.8‐fold and 9.2‐fold HOR improvement in mass activity and exchange current density, compared with the Pt/PC counterpart, respectively. CO‐stripping voltammetry tests demonstrate the anti‐CO poisoning ability of nanocatalysts, in the sequence of Ru‐increased ≥ PtRu3/PC‐300 > Pt‐increased > Pt/PC. From the perspective of engineering a near‐surface structure, this study may open up a new route for the development of high‐efficiency electrocatalysts with a strong electronic effect and oxophilic effect.

Subnanometer high-entropy alloy nanowires enable remarkable hydrogen oxidation catalysis

“…From the cyclic voltammograms (CVs) curves of various catalysts obtained in 0.1 M HClO 4 solution at a scan rate of 50 mV s −1 (Supplementary Fig. 13 ), we can see that the presence of Ru significantly broadens the electrical double-layer capacitor 20 , 21 . It is found that the anode current of HEA SNWs/C increases sharply with the potential (Fig.…”

Synergistic Electrocatalysts for Alkaline Hydrogen Oxidation and Evolution Reactions

“…[32] The oxophilic components can facilitate the capture of hydroxyl species, thereby accelerating the Volmer step. Typical OH capturers include oxophilic PGMs (Ru, Ir), [21,54,55] transition metals(Mo, W, Ni), [56,57] metal oxides (MoO 2 , WO 3 , NiO), metal hydro(oxy)oxides (Ni(OH) 2 , Co(OH) 2 , NiOOH), [58][59][60][61] and oxygen-deficient compounds such as ceria. [62,63] The oxophilic values (θ) of common transition metals for realizing OH binding energy can be found from the calculations by Kopp et al, [64] where Mn (θ = 0.4), Fe (θ = 0.4), Co (θ = 0.4), Ru (θ = 0.4), W (θ = 0.8), Mo (θ = 0.6), Ce (θ = 0.9), etc.…”

“…The surface segregation of Pt-Ru alloy catalysts was further investigated by Sun's group. [54] By controlling the annealing atmosphere and temperature, the near-surface atomic compositions of Pt-Ru alloys can be subtly regulated (Figure 5a). The Ar annealing atmosphere was conducive to the Ru atom segregation to the surface, leading to the Ru-increased surface, [32] Copyright 2021, John Wiley & Sons.…”

“…a-c) Reproduced with permission. [54] Copyright 2021, John Wiley & Sons. d) Reproduced with permission.…”

“…g) Equilibrium adsorption potentials for H ad and OH ad and h) experimentally measured exchange current density for hydrogen oxidation in the alkaline over different metals plotted with calculated H and OH adsorption potentials on various metal surfaces. a-c) Reproduced with permission [54]. Copyright 2021, John Wiley & Sons.…”