氧空位在CO₂光催化还原过程中往往发挥重要作用。本工作中, 用水热法合成了不同Bi掺杂量的二氧化铈光催化剂Ce_1-xBi_xO_2-δ, 其中Ce_0.6Bi_0.4O_2-δ在Xe灯照射下表现出最高的光催化活性, 其CO产率为纯二氧化铈纳米棒的4.6倍。X射线衍射(XRD)分析表明固溶体保留了二氧化铈的萤石结构;紫外-可见漫反射(UV-Vis)光谱表明固溶体可见光吸收增强;X射线光电子能谱 (XPS)和拉曼光谱(Raman)分析表明, 掺杂后氧空位浓度明显提高。结合原位傅里叶变换红外光谱(in-situ FT-IR), 发现引入Bi提高了固溶体中氧空位的浓度, 并改变了CO₂在催化剂表面上的吸附/活化行为, 光照下碳酸氢根、碳酸根、甲酸等中间产物明显增多, 从而增强了CO₂光催化还原性能。

Oxygen vacancy plays an important role in promoting CO₂ adsorption and reduction on photocatalysts. Bi was heavily doped into ceria, forming a solid solution catalyst Ce_1-xBi_xO_2-δ meanwhile maintaining the fluorite structure, to increase the oxygen vacancy concentration. The sample Ce_0.6Bi_0.4O_2-δ showed the highest photocatalytic activity with a CO yield of ～4.6 times that of the pristine ceria nanorods. Bi was homogeneously dispersed into the fluorite ceria which was confirmed by XRD and EDX elemental mapping. It has been evidenced by the results of Raman and XPS that Bi introduction boosts the concentration of oxygen vacancy in the solid solution that can facilitate the adsorption/activation of carbonate and bicarbonate intermediates on its surface according to in-situ FT-IR.