Sudrajat Hanggara, Fadlallah Mohamed M, Tao Shuxia, Kitta Mitsunori, Ichikuni Nobuyuki, Onishi Hiroshi
Department of Chemistry, Graduate School of Science, Kobe University, Kobe 657-8501, Japan and Department of Chemical Engineering, Faculty of Engineering, Universitas Jember, Jember 68121, Indonesia.
Center for Computational Energy Research, Department of Applied Physics, Eindhoven University of Technology, Eindhoven 5600, The Netherlands and Department of Physics, Faculty of Science, Benha University, Benha 13518, Egypt.
Phys Chem Chem Phys. 2020 Sep 8;22(34):19178-19187. doi: 10.1039/d0cp02822c.
Strontium titanate, SrTiO3, with the perovskite ABO3 structure is known as one of the most efficient photocatalyst materials for the overall water splitting reaction. Doping with appropriate metal cations at the A site or at the B site substantially increases the quantum yield to split water into H2 and O2. The site occupied by the guest dopant in the SrTiO3 host thus plays a key role in dictating the water splitting activity. However, little is known about the detailed structure of the dopant site in the host lattice. In this study, the local structure of In3+ cations, which were shown to improve the water splitting activity of SrTiO3, is investigated with X-ray absorption fine structure spectroscopy and density functional theory (DFT) calculations. The In3+ cations exclusively substitute for Ti4+ cations at the B site to form InO6 octahedra. Further optical experiments using UV-Vis diffuse reflectance spectroscopy and DFT calculations of the density of states indicate that the substitution of In3+ for Ti4+ does not alter the band structure and bandgap energy (remaining at 3.2 eV). The mechanism underlying the increased water splitting activity is discussed in relation to occupation of the B site by In3+ cations.
钛酸锶（SrTiO₃）具有钙钛矿ABO₃结构，是已知的用于全水分解反应的最有效的光催化剂材料之一。在A位或B位掺杂适当的金属阳离子会大幅提高将水分解为H₂和O₂的量子产率。因此，SrTiO₃主体晶格中客体掺杂剂占据的位置在决定水分解活性方面起着关键作用。然而，关于主体晶格中掺杂剂位置的详细结构却知之甚少。在本研究中，利用X射线吸收精细结构光谱和密度泛函理论（DFT）计算研究了In³⁺阳离子的局部结构，In³⁺阳离子已被证明可提高SrTiO₃的水分解活性。In³⁺阳离子仅在B位取代Ti⁴⁺阳离子以形成InO₆八面体。使用紫外可见漫反射光谱的进一步光学实验以及态密度的DFT计算表明，In³⁺取代Ti⁴⁺不会改变能带结构和带隙能量（保持在3.2 eV）。结合In³⁺阳离子对B位的占据情况讨论了水分解活性提高的潜在机制。
