Abstract

Cerium, nitrogen, and sulfur ions were doped into SrTiO₃ (STO) lattice by sol–gel method. PXRD results confirm the cubic perovskite structure for all the doped samples. Higher Ce dopant concentration leads to the formation of CeO₂ as a separate phase. X-ray density calculations show the solid to be of omission solid solution type material. A red shift in the absorption towards the visible region for all the doped samples was due to the formation of various mid-band gap states. FTIR technique confirms the presence of bidentately coordinated SO₄²⁻ ions on the surface of doped samples. The XPS technique confirms the presence of Ce³⁺, Ce⁴⁺, S⁶⁺ and two different types of nitrogen. The surface acidity of the doped catalyst increases by the presence of SO₄²⁻ and OH⁻ ions favoring efficient trapping of photogenerated electrons. The upward shift in the position of VB of doped samples by almost 0.26 eV reduces the band gap of CeNS-STO samples as confirmed by the VB XPS technique. The lower PL intensity and higher magnitude of photocurrent for Ce_0.48N_0.19S_0.44–SrTiO₃ (CeNS-STO (2)) sample corresponds to higher separation efficiency of photogenerated electron-hole pairs. The enhanced photocatalytic activity of CeNS-STO (2) sample under both UV/solar light may be attributed to the synergistic effect between the three dopants Ce⁴⁺, N³⁻, and S⁶⁺ narrow band gap, decreased crystallite size, mesoporous structure, and high surface area. Intermediate products were identified by HPLC analysis and a possible degradation reaction mechanism was proposed.

Incorporation of metal /nonmetal ions into the SrTiO₃ lattice creates donor and acceptor levels within the band gap. The Ce⁴⁺/Ce³⁺ and S⁶⁺ dopant energy levels are located below the CB band edge, whereas N^3-acceptor energy levels are located above the VB band and they are also merged within the VB based on its location in the interstitial or substitutional lattice sites. Figure shows various electronic transitions and possible degradation reaction pathways using CeNS-SrTiO₃ photocatalyst under the irradiation of solar light.

中文翻译：

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通过将Ce，N和S掺杂离子掺入SrTiO 3晶格中进行有效的带隙工程：探索紫外/太阳能光下的光催化活性

摘要

通过溶胶-凝胶法将铈，氮和硫离子掺杂到SrTiO ₃（STO）晶格中。PXRD结果证实了所有掺杂样品的立方钙钛矿结构。较高的Ce掺杂剂浓度导致CeO ₂形成为单独的相。X射线密度计算表明该固体是疏漏的固溶体型材料。对于所有掺杂样品，吸收向可见区的红移是由于形成了各种中带隙态。FTIR技术证实了掺杂样品表面上存在双配位SO ₄ ^2-离子。XPS技术证实了Ce ³⁺，Ce ⁴⁺，S ^6+的存在和两种不同类型的氮气 由SO的存在的掺杂的催化剂增加了表面酸度₄ ^2-和OH ^-离子有利于光生电子的有效地捕获。VB XPS技术证实，掺杂样品的VB位置向上移动近0.26 eV可以减小CeNS-STO样品的带隙。Ce _0.48 N _0.19 S _0.44 –SrTiO _3的PL强度较低，光电流强度较高（CeNS-STO（2））样品对应于光生电子-空穴对的更高分离效率。CeNS-STO（2）样品在紫外线/太阳光下均具有增强的光催化活性，这可能归因于三种掺杂剂Ce ⁴⁺，N ^3-和S ^6+的窄带隙之间的协同效应，微晶尺寸减小，介孔结构和高表面积。通过HPLC分析鉴定了中间产物，并提出了可能的降解反应机理。

将金属/非金属离子结合到SrTiO ₃晶格中，在带隙内产生供体和受体能级。Ce ⁴⁺ / Ce ³⁺和S ⁶⁺掺杂能级位于CB频带边缘以下，而N ^3-受体能级位于VB频带上方，它们也根据其在VB中的位置合并在VB内。间隙或替代晶格位点。图中显示了使用CeNS-SrTiO ₃光催化剂在太阳光照射下的各种电子跃迁和可能的降解反应途径。