Boosting CO_(2) photoreduction by synergistic optimization of multiple processes through metal vacancy engineering

通过金属空位工程促进CO_(2)光还原

The photoreduction of greenhouse gas CO_(2) using photocatalytic technologies not only benefits en-vironmental remediation but also facilitates the production of raw materials for chemicals.Howev-er,the efficiency of CO_(2) photoreduction remains generally low due to the challenging activation of CO_(2) and the limited light absorption and separation of charge.Defect engineering of catalysts rep-resents a pivotal strategy to enhance the photocatalytic activity for CO_(2),with most research on met-al oxide catalysts focusing on the creation of anionic vacancies.The exploration of metal vacancies and their effects,however,is still underexplored.In this study,we prepared an In2O3 catalyst with indium vacancies(VIn)through defect engineering for CO_(2) photoreduction.Experimental and theo-retical calculations results demonstrate that VIn not only facilitate light absorption and charge sepa-ration in the catalyst but also enhance CO_(2) adsorption and reduce the energy barrier for the for-mation of the key intermediate*COOH during CO_(2) reduction.Through metal vacancy engineering,the activity of the catalyst was 7.4 times,reaching an outstanding rate of 841.32μmol g(-1)h^(-1).This work unveils the mechanism of metal vacancies in CO_(2) photoreduction and provides theoretical guidance for the development of novel CO_(2) photoreduction catalysts.

随着化石燃料不断消耗,世界面临着严重的能源危机和环境恶化,迫切需要可持续的解决方案.利用太阳能将CO_(2)光还原成可燃和可利用的化学物质,是可持续和清洁能源转换的有效途径之一.In_(2)O_(3)是一种n型半导体,具有光学特性、化学稳定性、成本效益、无毒性质,在CO_(2)光还原中广泛应用.但In_(2)O_(3)光还原CO_(2)的效果还不能令人满意,这主要是由于CO_(2)与光催化剂的相互作用弱,In_(2)O_(3)的电荷分离效率相对较差.催化剂的缺陷工程是提高CO_(2)光催化活性的关键策略,目前,大部分研究聚焦于金属氧化物催化剂的阴离子空位的构建,但对金属空位及其效应的探索仍然不足.本文通过直接溶剂热和煅烧法成功合成了具有高密度铟空位(VIn)的In_(2)O_(3).高角度环形暗场扫描透射电镜结果表明合成的In_(2)O_(3)材料均表现出高度结晶的颗粒结构.紫外-可见光漫反射光谱结果表明,VIn的引入显著提高了催化剂的光吸收能力,结合莫特肖特基(Mott-Schottky)曲线结果,说明催化剂的能带结构合理,导带位置满足光催化还原CO_(2)的最低要求VIn的引入有效地降低了禁带宽度且导带位置更负,In_(2)O_(3)的还原能力更强.采用光致发光光谱、时间分辨光致发光光谱、光电流强度曲线和电化学阻抗曲线研究了催化剂的载流子分离行为,结果表明,VIn的引入显著提高了光生载流子分离率和电子寿命.Rama光谱、高分辨率X射线光电子能谱、密度泛函理论(DFT)计算结果佐证了VIn的存在.VIn的引入明显提高了催化效率、表观量子效率和太阳能转化为化学能的效率.原位漫反射红外傅里叶变换光谱和DFT计算结果表明,VIn作为CO_(2)活化的活性位点,有利于CO_(2)吸附和关键中间体*COOH的形成,且VIn可以降低CO_(2)转化速率决定步骤的能垒,促进CO产量的增加.结果表明,该催化剂的CO产率为841.32μmol g^(-1)h^(-1),是不含VIn的In_(2)O_(3)催化剂的7.4倍.综上所述,本文提供了一种构建金属空位的方法,有效地提高了In2O3的光还原CO_(2)活性,丰富了金属空位对光催化CO_(2)还原影响机制的理解,为设计更有效的CO_(2)还原光催化剂提供参考.