Stabilization by Configurational Entropy of the Cu(II) Active Site during CO Oxidation on Mg(0.2)Co(0.2)Ni(0.2)Cu(0.2)Zn(0.2)O.
Stabilization by Configurational Entropy of the Cu(II) Active Site during CO Oxidation on Mg(0.2)Co(0.2)Ni(0.2)Cu(0.2)Zn(0.2)O.
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DOI：
10.1021/acs.jpclett.0c00602
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发表时间：
2020-05-07
期刊：
影响因子：
--
通讯作者：
Torelli P
中科院分区：
文献类型：
--
作者：
Fracchia M;Ghigna P;Pozzi T;Anselmi Tamburini U;Colombo V;Braglia L;Torelli P
利用软X射线吸收光谱研究了CO在Mg_（0.2）Co_（0.2）Ni_（0.2）Cu_（0.2）Zn_（0.2）O高熵氧化物上的氧化机理。发现Cu是活性金属，当温度高于130 °C时，Cu（II）可被CO迅速还原为Cu（I）。Co和Ni在这方面没有任何作用。Cu（II）的氧化态可以很容易地但缓慢地恢复，通过用O2在约100 ℃下处理样品。250 °C。然而，应该注意的是，当在T > 100 °C下用CO处理时，CuO容易且不可逆地还原为Cu（I）。因此，这项工作的主要结论是，Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O的高构型熵稳定岩盐结构，并允许铜的氧化/还原是可逆的，从而允许催化循环发生。
The mechanisms of CO oxidation on the Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O high-entropy oxide were studied by means of operando soft X-ray absorption spectroscopy. We found that Cu is the active metal and that Cu(II) can be rapidly reduced to Cu(I) by CO when the temperature is higher than 130 °C. Co and Ni do not have any role in this respect. The Cu(II) oxidation state can be easily but slowly recovered by treatment of the sample with O2 at ca. 250 °C. However, it should be noted that CuO is readily and irreversibly reduced to Cu(I) when it is treated with CO at T > 100 °C. Thus, the main conclusion of this work is that the high configurational entropy of Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O stabilizes the rock-salt structure and permits the oxidation/reduction of Cu to be reversible, thus permitting the catalytic cycle to take place.
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