PdPb bimetallic nanowires as electrocatalysts for enhanced ethanol electrooxidation
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Published online 10 June 2020 | https://doi.org/10.1007/s40843-020-1350-7
PdPb bimetallic nanowires as electrocatalysts for enhanced ethanol electrooxidation †
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Ning Ma , Shuqing Wang , Xuehua Liu, Yunchang Sun, Yanru Yin, Lian Ying Zhang and * Peizhi Guo ABSTRACT Less-expensive but efficient electrocatalysts are essential to accelerate the commercialization of fuel cells. Herein, ultrathin PdPb nanowires (PdPb NWs) with a diameter of around 3.5 nm were prepared by using a one-step hydrothermal method. The introduction of Pb in Pd-based bimetallic nanostructures produced high differences in the morphology from Pd nanoparticles (NPs) to various PdPb NWs. All the as-prepared PdPb NWs exhibited better electrocatalytic activity and durability than Pd NPs due to the synergistic effect. Especially, Pd65Pb35 possessed the highest −1 current density of about 3460 mA mgPd for the ethanol electrooxidation which was around 6.3 times higher than commercial Pd/C. The high-performance of Pd65Pb35 is attributed to the defect-rich and stable nanowire structure with optimized surface atomic arrangement, as evidenced by high resolution transmission electron microscopy measurements and long-time treatment in an acidic media. The differences in the morphologies and electrocatalytic activities of PdPb NWs with varied Pb contents have also been discussed and analyzed. Keywords: PdPb nanowires, electronic structure, lattice defects, electrocatalysis, ethanol electrooxidation
INTRODUCTION Direct ethanol fuel cells (DEFCs) have attracted widespread concern due to their high energy density, conversion efficiency, low cost and safety for storage [1,2]. Palladium (Pd) is a commonly used and promising anode catalyst for DEFCs [3–6]. However, the limited reserves, high price, sluggish reaction kinetics and poor tolerance to poisoning intermediates of Pb hinder its commercialization. Compared with pure Pd, Pd-based bimetallic alloy catalysts can be a good choice, which can reduce the cost
and improve the electrocatalytic activity due to their synergistic effect between the two elements [7,8]. Hence, great efforts have been devoted to the syntheses of Pdbased bimetallic nanostructures, for example, Pd/Cu [9,10], Pd/Ag [11–13], Pd/Pb [14], Pd/Sn [15,16]. Especially, Pb has drawn increasing attention due to its stronger promoting effects on ethanol oxidation reaction (EOR), resulting in the geometric effect, the electronic effect as well as the bifunctional mechanism [17]. Additionally, high durability of the electrocatalyst is also a significant factor for its practical application [18,19]. Previous literatures demonstrated that the poisoning intermediates (such as carbonaceous residues) adsorbed on the catalyst surface would seriously reduce its catalytic activity [20]. Recent advances reveal that alloying Pd with Pb shows excellent tolerance to poisoning intermediates during the EOR by weakening the bond energy of Pd–CO or promoting the reaction more thoroughly. Apart from the bifunctional mechanism, the morphology and structure of the
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