Platinum–Ruthenium Single Atom Alloy as a Bifunctional Electrocatalyst toward Methanol and Hydrogen Oxidation Reactions

Abstract

The precise regulation for the structural properties of nanomaterials at the atomic scale is an effective strategy to develop high-performance catalysts. Herein, a facile dual-regulation approach was developed to successfully synthesize Ru 1 Pt n single atom alloy (SAA) with atomic Ru dispersed in Pt nanocrystals. High-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure demonstrated that Ru atoms were dispersed in Pt nanocrystals as single atoms. Impressively, the Ru 1 Pt n -SAA exhibited an ultrahigh specific activity (23.59 mA cm −2 ) and mass activity (2.805 mA/μg -PtRu ) for methanol oxidation reaction (MOR) and exhibited excellent exchange current density activity (1.992 mA cm −2 ) and mass activity (4.71 mA/μg -PtRu ) for hydrogen oxidation reaction (HOR). Density functional theory calculations revealed that the introduction of Ru atoms greatly reduced the reaction free energy for the decomposition of water molecules, which promoted the removal of CO* in the MOR process and adjusted the Gibbs free energy of hydrogen and hydroxyl adsorption to promote the HOR. Our work provided an effective idea for the development of high performance electrocatalysts.

Revealing the Effect of Surface Composition on Multiwalled Carbon Nanotubes Supported Pt‐Fe Alloy Electrocatalysts for Methanol Oxidation Performance

“…As presented in Figure 1a, the three diffraction peaks located at 40.5°, 46.5° and 67.7° correspond to the (111), (200) and (220) plane of the face‐centered cubic structure (fcc) of Pt. Moreover, the peak positions of Pt 1 Fe x @NC/MWCNTs shows a positive shift compared with pristine Pt (PDF #04‐0802), implying that Pt has been alloyed with Fe to form a bimetallic PtFe alloy with lattice shrinkage [43–45] . As key indicators for determining the alloy degree and thus the MOR electrocatalytic properties, the lattice contraction and strain variation are computed by the Debye‐Scherrer equation.…”

“…Moreover, the peak positions of Pt 1 Fe x @NC/MWCNTs shows a positive shift compared with pristine Pt (PDF #04-0802), implying that Pt has been alloyed with Fe to form a bimetallic PtFe alloy with lattice shrinkage. [43][44][45] As key indicators for determining the alloy degree and thus the MOR electrocatalytic properties, the lattice contraction and strain variation are computed by the Debye-Scherrer equation. As exhibited in Table S1, the strain variation of 2.46 % for the Pt 1 Fe 3 @NC/MWCNTs sample is higher than that of 1.72 % for Pt 1 Fe 1 @NC/MWCNTs, 1.99 % for Pt 1 Fe 2 @NC/ MWCNTs, and 1.91 % for Pt 1 Fe 4 @NC/MWCNTs, implying that introducing appropriate Fe atoms can cause higher strain variation and larger alloying degree than when introducing low or excessive Fe atoms.…”

Toward Electrocatalytic Methanol Oxidation Reaction: Longstanding Debates and Emerging Catalysts

“…The Ru 1 Pt n SAA (single Ru atoms dispersed in Pt nanocrystals) developed by Liang's group also exhibited superior MOR activity with a high SA of 23.59 mA cm −2 and MA of 2.805 mA µg −1 PtRu which is 21.0 and 3.84 times higher than that of Pt/C, respectively (Figure 7f). [ 116 ] The absence of Ru−Ru scattering in the Fourier transformed‐extended X‐ray absorption fine structure (FT‐EXAFS) curves of Ru K‐edge indicates that Ru is atomically dispersed in Pt nanocrystals (Figure 7g). XAFS, X‐ray photoelectron spectroscopy (XPS), as well as the DFT results show that electrons transferred from Ru atoms to Pt atoms in Ru 1 Pt n ‐SAA.…”

“…h) Calculated optimal MOR pathways on Pt(111), PtRu-alloy(111), and Ru 1 Pt n -SAA(111). f-h) Reproduced with permission [116]. Copyright 2022, American Chemical Society.…”

Thermally Methanol Oxidation via the Mn1@Co3O4(111) Facet: Non-CO Reaction Pathway

“…Direct methanol fuel cells (DMFCs) have been regarded as one of the most prospective energy storage and conversion devices . Efficient catalysts of the methanol oxidation reaction (MOR) are critical in the development of DMFCs . In general, MOR catalytic systems are the oxides, nonoxides, and carbon-based catalysts. − Single-atom catalysts that offer the means of reducing the costs associated with preparation and utilization of noble metal catalysts have become promising alternatives for methanol oxidation reaction to address the bottleneck in low efficiency in the past decade. − Various single-atom catalysts for MOR were designed and synthesized. − Pt/α-MoC presented by Ma exhibited a particular efficiency for methanol aqueous-phase reforming, as well as the latter Ni/α-MoC. , Pd 1 /Fe 3 O 4 , designed and synthesized by Rousseau, preferred the excellent catalytic performance for partial oxidation of methanol.…”