Measurements of SrTiO3 doped with transition metals

Redox exsolution is a recently discovered “inside-out” route to produce metal supported nanoparticles as promising heterogeneous catalyst for a wide range of applications. In the frame of perovskite oxide SrTiO3 is one of the most used supports due to its chemical and thermal stability as well as its activity in catalysis. In the past few years, it has been doped with a variety of transition metals (e. g. Fe, Ni, Cu) to produce catalysts, and, among these transition metals, of particular interests is the Fe case, being a low cost, highly available active metal. However, Fe alone can’t exsolve, and the presence of Ni is necessary in order to exsolve the metal. The reason for this anomalous behaviour is still under debate, and further investigation are needed. For this reason, SrTiO3 samples co-doped with Fe and Ni (with concentration as low as 0,1%) will be measured with both in situ and ex situ XAS and the results, coupled with EPR spectroscopy, will shed new light on this topic.

氧化还原析出（Redox exsolution）是近年发现的一种"由内而外"制备金属负载型纳米颗粒的方法，这类纳米颗粒作为多相催化剂在诸多应用领域中拥有广阔前景。在钙钛矿氧化物体系中，钛酸锶（SrTiO3）凭借优异的化学稳定性、热稳定性及催化活性，成为最为常用的载体之一。过往数年，科研人员通过掺杂多种过渡金属（如铁（Fe）、镍（Ni）、铜（Cu））对其进行改性以制备催化剂；其中铁基催化体系尤为引人关注，因其活性金属成本低廉且储量丰富。然而，单一铁元素无法发生氧化还原析出，必须引入镍元素才能实现金属相的析出。目前，这种反常行为的成因仍存在争议，尚需开展更多深入研究。鉴于此，本研究将采用原位（in situ）与非原位（ex situ）X射线吸收谱（X-ray Absorption Spectroscopy，XAS）对铁镍共掺杂的钛酸锶（SrTiO3）样品进行表征测试，其中掺杂浓度可低至0.1%；结合电子顺磁共振波谱（Electron Paramagnetic Resonance，EPR）的表征结果，将为该研究主题带来全新的见解。