Catalytic Activity of Pd/Cu Random Alloy Nanoparticles for Oxygen Reduction
Catalytic Activity of Pd/Cu Random Alloy Nanoparticles for Oxygen Reduction
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DOI：
10.1021/jz2004717
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发表时间：
2011-06-02
影响因子：
5.7
通讯作者：
Henkelman, Graeme
中科院分区：
文献类型：
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作者：
Tang, Wenjie;Zhang, Liang;Henkelman, Graeme
钯/铜双金属无规合金纳米颗粒的氧还原活性的趋势是通过计算氧结合的范围组成。当钯中加入Cu时，平均氧结合降低，表明催化活性增加，Pd/Cu比为1:1时达到峰值。计算表明，Cu降低了Pd- o的结合能，而Pd增加了Cu- o的结合能。这些变化可以理解为从Pd到Cu的电荷转移，Pd的d带中心降低，Cu的d带中心升高。活动的高峰出现是因为这两种影响并不等同。钯的d态与吸附的氧之间有较大的重叠，使得钯上的结合减少比铜上的结合增加更显著。我们提出了一个简单的平均结合能模型，可以普遍地预测随机合金的活度趋势。
Trends in oxygen reduction activity of Pd/Cu bimetallic random alloy nanoparticles are determined with calculations of oxygen binding for a range of compositions. A reduction in the average oxygen binding is found as Cu is added to Pd, indicating an increase in catalytic activity up to a peak at 1:1 Pd/Cu ratio. Calculations show that Cu reduces the Pd-O binding energy and Pd increases the Cu-O binding energy. These changes are understood in terms of charge transfer from Pd to Cu, lowering the d-band center of Pd and raising that of Cu. The peak in activity occurs because these two effects not equivalent. A greater overlap between the d-states of Pd and the adsorbed oxygen makes the reduction in binding at Pd more significant than the increase in binding at Cu. We present a simple model of the average binding energy that can generally predict activity trends in random alloys.