N掺杂TiO2纳米纤维高可见光催化CO2合成甲醇

采用气相生长法在介孔SiO₂球的表面上制备了? 8~10 nm的TiO₂纳米纤维, 采用相同的方法, 还成功地制备了氮掺杂的TiO₂(N-TiO₂) 纳米纤维, 它具有更高的可见光催化活性。采用X射线光电子能谱(XPS)、紫外光电子能谱(UPS)、X射线衍射(XRD)、扫描电镜(SEM)、透射电子显微镜(TEM)、紫外–可见分光光度计(UV-Vis)、荧光分光光度计(PL)等对样品进行了测试分析。TiO₂纳米纤维具有高结晶度的锐钛矿晶型, 掺氮后的TiO₂纳米纤维带隙变窄, 在可见光波段有明显的吸收, 同时, 光生电子还原能力更强, 大大提高了可见光下催化还原CO₂合成甲醇的产率。在300 W氙灯光照2 h后, 用纯TiO₂纤维催化CO₂合成甲醇, 产率为493.4 μmol?g^-1?h^-1, 转换频率(TOF) 为0.089 h^-1; 以N-TiO₂为催化剂合成甲醇产率提高了40.1%, 达695.1 μmol?g^-1?h^-1, 转换频率(TOF) 提高了40.4%, 为0.125 h^-1。

Photocatalytic Reduction of Carbon Dioxide to Methanol over N-doped TiO2 Nanofibers under Visible Irradiation

TiO₂ nanofibers with a diameter size of 8-10 nm were prepared on the surface of the mesoporous SiO₂ spheres through a vapor-phase growth method. And nitrogen doped TiO₂ (N-TiO₂) nanofibers were also successfully fabricated in the same way. The N atoms replaced the oxygen sites in the lattices of TiO₂. The N-TiO₂ nanofibers exhibited a highly catalytic activity under visible irradiation. XPS, UPS, XRD, SEM, TEM, UV-Vis, and PL were used to analyze and characterize the nanofibers. The annealed nanofibers were composed of highly crystalline anatase phase. Nitrogen doping narrowed band gap of the TiO₂ nanofibers and enhanced absorption of the visible light. Meanwhile, photo-generated electrons over the N-TiO₂ nanofibers exhibited more reductive potential than those over the TiO₂ nanofibers. Thus, methanol yield was remarkably improved in CO₂ photocatalytic reduction. Upon irradiation of 300 W Xe lamp for 2 h, methanol yield was 493.4 μmol?g^-1?h^-1 over the N-doped TiO₂ nanofibers, and the corresponding turnover frequency (TOF) was 0.089 h^-1. Comparatively, methanol yield reached 695.1 μmol?g^-1?h^-1 for N-TiO₂ with a TOF of 0.125 h^-1, which enhanced by 40.1% and 40.4%, respectioely.