Abstract
Although platinum nanocrystals have been considered as potential electrocatalysts for methanol oxidation reaction (MOR) in fuel cells, the large-scale practical implementation has been stagnated by their limited abundance, easy poisoning, and low durability. Here, grain boundary-enriched platinum (GB-Pt) scaffolds are produced in large scale via facilely reducing fast cryomediated dynamic equilibrium hydrolysates of platinum salts. Such plentiful platinum grain boundaries are originated from the fast fusion of short platinum nanowires during reduction of the individually and homogeneously dispersed platinum intermediates. These grain boundaries can provide abundant active sites to efficiently catalyze MOR and meanwhile enable to oxidize the adsorbed poisonous CO during the electrocatalytic process. As a consequence, the as-synthesized GB-Pt scaffolds exhibit an impressively high mass activity of 1027.1 mA mgPt−1 for MOR, much higher than that of commercial Pt/C (345.2 mA mgPt−1), as well as good stability up to 5000 cycles. We are confident that this synthetic protocol can be further extended to synthesize various grain boundary-enriched metal scaffolds with broad applications in catalysis.
Highlights
Direct methanol fuel cells (DMFCs) have been demonstrated as one of the most promising power sources for electronic mobile devices and electric vehicles due to their ultrahigh energy densities and low pollution [1,2,3]
From the perspective of Pt atomic efficiency [12], the precisely controlled synthesis of Pt nanocrystals such as Pt irregular nanoparticles [13, 14], nanowires [15,16,17,18], and nanorods [19] is highly desirable since they have inherent anisotropic morphologies with abundant low-coordinated surface atoms [20, 21], enabling to slow down the ripening process and increase the electrocatalytic activities for methanol oxidation
It is demonstrated that Pt nanocrystals with twin defects or dislocations have shown unique electrocatalytic behaviors for methanol oxidation, differentiating from coarsely gained grains, single crystals, or particles [21,22,23], since Pt atoms close to defects have decreased the number of neighbors in the first coordination shell, and are favorable to forcefully adsorb the reactants and catalyze related bond-breaking reactions during the catalytic process [24, 25]
Summary
Direct methanol fuel cells (DMFCs) have been demonstrated as one of the most promising power sources for electronic mobile devices and electric vehicles due to their ultrahigh energy densities and low pollution [1,2,3]. Their wide applications have stagnated owing to the notoriously sluggish kinetics of methanol oxidation reaction (MOR) at the anode [4,5,6,7,8]. To date, it remains a big challenge to synthesize grain boundary-enriched Pt nanocrystals via a facile and cost-efficient approach [28, 29]
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