Oxygen-Vacancy-Induced Formation of Pt-Based Intermetallics on MXene with Strong Metal-Support Interactions for Efficient Oxygen Reduction Reaction

The Pt-based alloys can moderate the binding energies of oxygenated species on the catalytic surface, endowing the superior catalytic performance towards oxygen reduction reaction (ORR). Nevertheless, it is still challenging to explore general methods to synthesize structurally ordered intermetallics with uniform distributions. Herein, the strong metal-support interaction is employed to facilitate the interdiffusion of Pt/M atoms by establishing a tunnel of oxygen vacancy on ultrathin Ti3C2Tx (MXene) sheets, synthesizing the ordered PtFe, PtCo, PtZn, PdFe, PdZn intermetallics loaded onto Ti3C2Tx. Furthermore, the in-situ generation of Ti-O from Ti3C2Tx could be bonded with Pt and forming Pt-O-Ti, resulting in charge redistribution through Pt-O-Ti structure. Theoretical calculations demonstrate that the valuable charge redistribution can be observed at the interface and extended even to at the distance of two nanometers from the interface, which can modulate the Pt-Pt distance, optimize Pt-O binding energy and enhance intrinsic activity towards ORR. The strong coupling interaction between PtFe and Ti3C2Tx containing the titanium oxide layer endows the high stability of the composites. This work not only presents a general synthesis strategy for intermetallics but also provides a new insight that metal-support interaction is essential for the structural evolution of intermetallics on materials with oxygen vacancies.

Emerging Pt-based intermetallic nanoparticles for the oxygen reduction reaction

The advancement of highly efficient and enduring platinum (Pt)-based electrocatalysts for the oxygen reduction reaction (ORR) is a critical determinant to enable broad utilization of clean energy conversion technologies. Pt-based intermetallic electrocatalysts offer durability and superior ORR activity over their traditional analogues due to their definite stoichiometry, ordered and extended structures, and favourable enthalpy of formation. With the advent in new synthetic methods, Pt-based intermetallic nanoparticles as a new class of advanced electrocatalysts have been studied extensively in recent years. This review discusses the preparation principles, representative preparation methods of Pt-based intermetallics and their applications in the ORR. Our review is focused on L10 Pt-based intermetallics which have gained tremendous interest recently due to their larger surface strain and enhanced M(3d)-Pt(5d) orbital coupling, particularly in the crystallographic c-axis direction. Additionally, we discuss future research directions to further improve the efficiency of Pt-based intermetallic electrocatalysts with the intention of stimulating increased research ventures in this domain.

A phosphate tolerant Pt-based oxygen reduction catalyst enabled by synergistic modulation of alloying and surface modification

Addressing phosphoric acid poisoning of platinum-based catalysts in high-temperature fuel cells still remains a strategic and synthetic problem. Here, we synthesized a Pt3Co@MoOx-NC catalyst with a Pt3Co active core and MoOx modification on the surface, which simultaneously exhibits high ORR activity and phosphate tolerance.

Pt-Mo/C, Pt-Fe/C and Pt-Mo-Sn/C Nanocatalysts Derived from Cluster Compounds for Proton Exchange Membrane Fuel Cells

Nanosized bimetallic PtMo, PtFe and trimetallic PtMoSn catalysts deposited on highly dispersed carbon black Vulcan XC-72 were synthesized from the cluster complex compounds PtCl(P(C6H5)3)(C3H2N2(CH3)2)Mo(C5H4CH3)(CO)3, Pt(P(C6H5)3)(C3N2H2(CH3)2)Fe(CO)3(COC6H5C2C6H5), and PtCl(P(C6H5)3)(C3N2H2(CH3)2)C5H4CH3Mo(CO)3SnCl2, respectively. Structural characteristics of these catalysts were studied using X-ray diffraction (XRD), microprobe energy dispersive spectroscopy (EDX), and transmission electron microscopy (TEM). The synthesized catalysts were tested in aqueous 0.5 M H2SO4 in a three-electrode electrochemical cells and in single fuel cells. Electrocatalytic activity of PtMo/C and PtFe/C in the oxygen reduction reaction (ORR) and the activity of PtMoSn/C in electrochemical oxidation of ethanol were evaluated. It was shown that specific characteristics of the synthesized catalysts are 1.5–2 times higher than those of a commercial Pt(20%)/C catalyst. The results of experiments indicate that PtFe/C, PtMo/C, and PtMoSn/C catalysts prepared from the corresponding complex precursors can be regarded as promising candidates for application in fuel cells due to their high specific activity.

Achievements in Pt nanoalloy oxygen reduction reaction catalysts: strain engineering, stability and atom utilization efficiency

The Pt nanoalloy surfaces often show unique electronic and physicochemical properties that are distinct from those of their parent metals, which provide significant room for manipulating their oxygen reduction reaction (ORR) behaviour. In this Feature Article, we present the progress of our recent research and that of other groups in Pt nanoalloy catalysts for ORR from three aspects, namely, strain engineering, stability and atom utilization efficiency. Some new insights into Pt surface strain engineering will be firstly introduced, with a focus on discussing the effect of compressive and tensile strain on the chemisorption properties. Secondly, the design concepts and synthetic methodologies to intensify the inherent stability of Pt nanoalloys will be summarized. Then, the exciting research push in developing nanostructured alloys with high atom utilization efficiency of Pt will be presented. Finally, a brief illumination of challenges and future developing perspectives of Pt nanoalloy catalysts will be provided.

A bimodal-pore strategy for synthesis of Pt3Co/C electrocatalyst toward oxygen reduction reaction

A bimodal-pore strategy was developed for preparation of the Pt3Co/C catalyst with active Pt3Co nanoparticles located around the mass transfer channels rather than inside them, which leads to ca. 29% higher mass transfer efficiency and a superior single-cell performance under an ultralow Pt loading.

AuIr alloy with arbitrarily adjustable lattice parameters as a highly efficient electrocatalyst for the oxygen reduction reaction

AuIr alloy nanoparticles were successfully prepared without using surfactants for the first time despite Au and Ir being immiscible according to phase diagrams. The lattice parameters of the AuIr alloy can be adjusted arbitrarily. The oxygen reduction reaction (ORR) activity of Au5Ir5 alloy is better than that of Au or Ir, and the oxygen evolution reaction (OER) activity of the Au5Ir5 alloy is as good as that of Ir in alkaline solution.