Abstract In this study, the gadolinium (Gd), iron (Fe), and nitrogen (N) doped TiO2 nanomaterials have been synthesized by a sol–gel method with slight modification. While the effect of Gd on the crystalline morphology, specific surface area, chemical composition, and bandgap of the doped samples have been investigated by SEM, TEM, BET, XRD, UV–vis, and XPS. The bonds of Ti–O–Gd, N–Ti–O, and O–N–Ti induced by Gd and N substitution inside the TiO2 crystal lattice structure have been investigated by XPS. The UV–vis spectra showed that the absorption edges of all doped samples are significantly red-shifted, further extending towards the visible spectrum, owing to the impurity band formation of the above valence band (VB) by doping of N. With the increase in the Gd doping amount, the photocatalytic efficiency of GFNTO (tri-doped samples) followed the sequence: G2.0FNTO > G2.5FNTO > G3.0FNTO > G1.5FNTO > G3.5FNTO > G1.0FNTO. The first-order reaction constant of G2.0FNTO for photodegradation of methylene blue (MB) is ten times higher than that of un-doped TiO2. The significant improvement in the performance of the co-doped sample is due to the finer particle size, larger specific surface area, narrowed bandgap, more defect sites, and oxygen vacancies induced by the substitution of Ti4+ by N, Fe3+, and Gd3+. The recycling experiment showed that the photocatalytic efficiency of G2.0FNTO can still reach 95% after its five cycles, further exhibiting the excellent stability and re-usability.

中文翻译：

---

Gd、Fe、N共掺杂TiO2纳米材料在可见光下增强光催化活性的系统研究

摘要 在本研究中，通过溶胶-凝胶法稍加修饰合成了钆 (Gd)、铁 (Fe) 和氮 (N) 掺杂的 TiO2 纳米材料。已经通过 SEM、TEM、BET、XRD、UV-vis 和 XPS 研究了 Gd 对掺杂样品的晶体形态、比表面积、化学成分和带隙的影响。XPS 研究了在 TiO2 晶格结构内由 Gd 和 N 取代引起的 Ti-O-Gd、N-Ti-O 和 O-N-Ti 键。UV-vis 光谱显示所有掺杂样品的吸收边显着红移，进一步向可见光谱延伸，这是由于通过掺杂 N 形成了上述价带 (VB) 的杂质带。 Gd掺杂量，GFNTO（三掺杂样品）的光催化效率遵循以下顺序：G2.0FNTO > G2.5FNTO > G3.0FNTO > G1.5FNTO > G3.5FNTO > G1.0FNTO。G2.0FNTO 光降解亚甲蓝 (MB) 的一级反应常数是未掺杂 TiO2 的 10 倍。共掺杂样品性能的显着改善是由于更细的粒径、更大的比表面积、更窄的带隙、更多的缺陷位点以及由 N、Fe3+ 和 Gd3+ 取代 Ti4+ 引起的氧空位。回收实验表明，G2.0FNTO的光催化效率在经过5次循环后仍能达到95%，进一步表现出优异的稳定性和可重复使用性。G2.0FNTO 光降解亚甲蓝 (MB) 的一级反应常数是未掺杂 TiO2 的 10 倍。共掺杂样品性能的显着改善是由于更细的粒径、更大的比表面积、更窄的带隙、更多的缺陷位点以及由 N、Fe3+ 和 Gd3+ 取代 Ti4+ 引起的氧空位。回收实验表明，G2.0FNTO的光催化效率在经过5次循环后仍能达到95%，进一步表现出优异的稳定性和可重复使用性。G2.0FNTO 光降解亚甲蓝 (MB) 的一级反应常数是未掺杂 TiO2 的 10 倍。共掺杂样品性能的显着改善是由于更细的粒径、更大的比表面积、更窄的带隙、更多的缺陷位点以及由 N、Fe3+ 和 Gd3+ 取代 Ti4+ 引起的氧空位。回收实验表明，G2.0FNTO的光催化效率在经过5次循环后仍能达到95%，进一步表现出优异的稳定性和可重复使用性。和由 N、Fe3+ 和 Gd3+ 取代 Ti4+ 引起的氧空位。回收实验表明，G2.0FNTO的光催化效率在经过5次循环后仍能达到95%，进一步表现出优异的稳定性和可重复使用性。和由 N、Fe3+ 和 Gd3+ 取代 Ti4+ 引起的氧空位。回收实验表明，G2.0FNTO的光催化效率在经过5次循环后仍能达到95%，进一步表现出优异的稳定性和可重复使用性。