A位缺陷对La-Sr-Co-O钙钛矿结构和催化氧化性能的影响

采用柠檬酸络合法制备La-Sr-Co-O钙钛矿, 通过酸处理溶解Sr离子, 得到了相应的A位缺陷钙钛矿. 采用X射线衍射(XRD)、 X射线吸收精细结构(XAFS)、 电感耦合等离子体原子发射光谱(ICP-OES)、 X 射线光电子能谱(XPS)和拉曼光谱(Raman)等表征技术考察了A位缺陷钙钛矿的晶体结构、 配位环境及表面电子结构等性质, 通过CO氧化和NO氧化活性测试评价了A位缺陷钙钛矿的催化性能. 结果表明, 简单酸处理有选择性地改造了Sr富集区, 溶解了SrCO₃ 以及大部分SrO. 钙钛矿主体结构基本不变, 局域结构中Sr(A位)的缺位造成Co离子以Co₃O₄形式溶出, 并形成了更多的氧缺陷, 有效地活化了晶格氧物种, 因此其在CO氧化和NO氧化反应中均表现出更优异的低温活性.

Effect of A Site-deficiency on the Structure and Catalytic Oxidation Activity of the La-Sr-Co-O Perovskite

The La-Sr-Co-O perovskite was prepared by citrate acid complex method， and then the Sr ions was selectively dissolved to obtain A site-deficient perovskite. The changes of phase structure， coordination environment and electronic properties of the A site-deficient perovskite were investigated by powder X-ray diffraction（XRD）， X-ray absorption fine structures（XAFS）， inductively coupled plasma-optical emission spectro- scopy（ICP-OES）， X-ray photoelectron spectroscopy（XPS） and Raman spectra characterization techniques. The corresponding catalytic activity was also evaluated through the CO and NO oxidation reaction. The results show that Sr-rich region is reconstructed by acid treatment through selective dissolving SrCO₃ and SrO. The deficiency of Sr（A-site） lead to the exsolution of Co in the form of new Co₃O₄ phase. More oxygen vancancies were also generated， which facilitates the generation of oxygen vacancy and activation of the lattice oxygen species. Therefore， the A site-deficient perovskite performed better CO and NO oxidation ability under low temperatures.