An effective strategy for small-sized and highly-dispersed palladium nanoparticles supported on graphene with excellent performance for formic acid oxidation
An effective strategy for small-sized and highly-dispersed palladium nanoparticles supported on graphene with excellent performance for formic acid oxidation
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DOI：
10.1039/c0jm03361h
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发表时间：
2011-02
影响因子：
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通讯作者：
Jun Yang;Chungui Tian;Lei Wang;H. Fu
中科院分区：
文献类型：
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作者：
Jun Yang;Chungui Tian;Lei Wang;H. Fu
本文报道了在不使用任何表面活性剂的情况下，通过控制还原途径，在石墨烯上合成了尺寸和分散度可控的钯纳米粒子。通过有效的分步化学还原途径，可以在石墨烯上制备小尺寸、高分散的Pd NPs。通过首先引入部分剂量的还原剂，PdCl42−离子在氧化石墨烯（表示为GO）存在下被还原成Pd NPs，而GO不完全还原。因此，Pd NPs可以被氧化石墨烯的氧基锚定和稳定（样品记为Pd/GO）。第二步，随着剩余还原剂的加入，由于氧化石墨烯的氧化基团被大量去除，Pd/GO进一步转化为Pd/石墨烯。通过分步化学还原，制备出尺寸较小（约3 nm）的Pd NPs，并将其高度分散在石墨烯上（记为Pd/GN2）。相比之下，同步化学还原得到的Pd NPs尺寸大（约10 nm），分散性差（记为Pd/GN1）。值得注意的是，与同步化学还原法制备的Pd/GN1催化剂和Pd/Vulcan XC-72R碳催化剂相比，采用分步化学还原法制备的Pd/GN2催化剂对甲酸电氧化具有优异的催化活性和稳定性。钯/GN2催化剂性能的增强应归因于钯纳米粒子的小尺寸和高分散性以及石墨烯载体的稳定作用。
In this paper, we report the synthesis of Pd nanoparticles (NPs) with controllable size and dispersion supported on graphene by controlling the reduction pathway without any surfactants. The small-sized and highly-dispersed Pd NPs on graphene could be obtained through an effective separated step chemical reduction route. By first introducing a partial dosage of the reducing agent, PdCl42− ions were reduced to form Pd NPs in the presence of graphene oxide (denoted as GO), while GO was incompletely reduced. Thereby, Pd NPs could be anchored and stabilized by the oxygenated group of GO (the sample was denoted as Pd/GO). In the second step, with the addition of the rest of the reducing reagent, Pd/GO was further transformed into Pd/graphene due to the mass removal of oxygenated group of GO. By separated step chemical reduction, the Pd NPs with small size (about 3 nm) were highly dispersed on graphene (denoted as Pd/GN2). In contrast, the Pd NPs obtained from the synchronous chemical reduction had a large size (about 10 nm) and poor dispersion (denoted as Pd/GN1). Notably, the Pd/GN2 catalyst prepared by the separated step chemical reduction exhibited excellent catalytic activity and stability towards formic acid electrooxidation compared with the Pd/GN1 catalyst obtained from the synchronous chemical reduction and the Pd/Vulcan XC-72R carbon catalyst. The enhanced performance of Pd/GN2 catalyst should be contributed to the small size and high dispersion of Pd NPs and the stabilizing effect of the graphene support.