Tuning Surface Structure of Pd₃Pb/Pt_nPb Nanocrystals for Boosting the Methanol Oxidation Reaction

Abstract

Developing an efficient Pt‐based electrocatalyst with well‐defined structures for the methanol oxidation reaction (MOR) is critical, however, still remains a challenge. Here, a one‐pot approach is reported for the synthesis of Pd3Pb/PtnPb nanocubes with tunable Pt composition varying from 3.50 to 2.37 and 2.07, serving as electrocatalysts toward MOR. Their MOR activities increase in a sequence of Pd3Pb/Pt3.50Pb << Pd3Pb/Pt2.07Pb < Pd3Pb/Pt2.37Pb, which are substantially higher than that of commercial Pt/C. Specifically, Pd3Pb/Pt2.37Pb electrocatalysts achieve the highest specific (13.68 mA cm−2) and mass (8.40 A mgPt −1) activities, which are ≈8.8 and 6.8 times higher than those of commercial Pt/C, respectively. Structure characterizations show that Pd3Pb/Pt2.37Pb and Pd3Pb/Pt2.07Pb are dominated by hexagonal‐structured PtPb intermetallic phase on the surface, while the surface of Pd3Pb/Pt3.50Pb is mainly composed of face‐centered cubic (fcc)‐structured PtxPb phase. As such, hexagonal‐structured PtPb phase is much more active than the fcc‐structured PtxPb one toward MOR. This demonstration is supported by density functional theory calculations, where the hexagonal‐structured PtPb phase shows the lowest adsorption energy of CO. The decrease in CO adsorption energy and structural stability also endows Pd3Pb/PtnPb electrocatalysts with superior durability relative to commercial Pt/C.

Ga‐Doped Intermetallic Pd3Pb Nanocubes as a Highly Efficient and Durable Oxygen Reduction Reaction Electrocatalyst

“…However, it is still difficult to widely commercialize this fuel cell technology mainly due to the sluggish kinetics of oxygen reduction reaction (ORR) at the cathode [3,4] . Up to now, Pt‐based nanocrystals have regarded as the most active and efficient electrocatalysts for ORR [5–7] . However, the high cost and low abundance of Pt on earth severely hinder its widespread use in fuel cells [8,9] .…”

A Highly Active Rh@Pd Nanocube Catalyst for Methanol Electrooxidation

“…As alternatives to Pt, Pd and Rh catalysts have been utilized for the MOR because of their high catalytic activity to break the C-H bond and simultaneously their strong anti-CO-poisoning ability. [13][14][15][16][17][18][19][20][21][22][23][24] For example, great efforts have been devoted recently to optimizing the Rh-based catalysts with respect to their morphologies and structures for accelerated MOR. Synthesized Rh nanosheets, [14,15] hollow nanospheres, [16] and nanodendrites [18] display high mass activity (more than 300 A g metal À1 ) and a small oxidation potential (lower than 600 mV) for the MOR.…”

“…Synthesized Rh nanosheets, [14,15] hollow nanospheres, [16] and nanodendrites [18] display high mass activity (more than 300 A g metal À1 ) and a small oxidation potential (lower than 600 mV) for the MOR. Meanwhile, various nanostructured Pd catalysts have shown outstanding activity toward the MOR, including Pd nanotubes, [21] nanocubes, [22] and mesoporous [24] and dendritic nanoalloys. [25] It has to be pointed out that the surface structures and crystal planes of these catalysts play a crucial role in the MOR performance.…”

In Situ Synthesis of Surface-Mounted Novel Nickel(II) Trimer-Based MOF on Nickel Oxide Hydroxide Heterostructures for Enhanced Methanol Electro-Oxidation

“…The development of new, economical, and recyclable energy materials to reduce the consumption of fossil fuels and their harmful effects on the natural environment and human beings has become a research focus in recent decades. Direct methanol fuel cells (DMFCs), with their advantages of high efficiency, high energy density, and low cost, have attracted extensive attention in the field of the sustainable energy conversion scheme ( Wu X. et al, 2019 ; Dao et al, 2019 ; Li H. et al, 2020 ; Zhu et al, 2020 ). The methanol oxidation reaction (MOR) requires efficient electrocatalysts to promote sluggish reaction kinetics ( Wang Q. et al, 2020 ).…”