Acidity of surface-infiltrated binary oxides as a sensitive descriptor of oxygen exchange kinetics in mixed conducting oxides
Acidity of surface-infiltrated binary oxides as a sensitive descriptor of oxygen exchange kinetics in mixed conducting oxides
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DOI：
10.1038/s41929-020-00520-x
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发表时间：
2020-10-05
期刊：
影响因子：
37.8
通讯作者：
Tuller, Harry L.
中科院分区：
文献类型：
--
作者：
Nicollet, Clement;Toparli, Cigdem;Tuller, Harry L.
改善氧化物表面上O-2还原的动力学在许多能源和燃料转化技术中是至关重要的。在这里，我们表明，二元氧化物的酸度标度是一个强大的描述符，用于调整和预测混合导电氧化物上的氧表面交换动力学。通过在Pr表面渗透一系列从强碱性（Li 2 O）到强酸性（SiO2）的二元氧化物，（0.1）铈（0.9）O（2-delta）样品，可以将化学表面交换系数k（chem）改变6个数量级，碱性氧化物如Li 2 O使k（chem）增加近1,000倍，表面浓度低至50 ppm影响K（化学）。引人注目的是，虽然指前ofk（化学）与渗透的二元氧化物的酸度成线性关系，但活化能几乎没有变化。这些戏剧性的变化的起源，建议产生从系统的电子浓度的增加在Pr0.1Ce0.9O2-δ表面的渗透的二元氧化物的酸度降低。
Improving the kinetics of O-2 reduction on oxide surfaces is critical in many energy and fuel conversion technologies. Here we show that the acidity scale for binary oxides is a powerful descriptor for tuning and predicting oxygen surface exchange kinetics on mixed conducting oxides. By infiltrating a selection of binary oxides from strongly basic (Li2O) to strongly acidic (SiO2) onto the surface of Pr(0.1)Ce(0.9)O(2-delta)samples, it was possible to vary the chemical surface exchange coefficient k(chem) by 6 orders of magnitude, with basic oxides such as Li2O increasing k(chem) by nearly 1,000 times, with surface concentrations as low as 50 ppm impacting k(chem). Strikingly, although the pre-exponential ofk(chem)scales linearly with the acidity of the infiltrated binary oxide, there is nearly no change in the activation energy. The origin of these dramatic changes is proposed to arise from the systematic increase in electron concentration at the Pr0.1Ce0.9O2-delta surface with the decreasing acidity of the infiltrated binary oxide.