富含氧空位纳米TiO_(2)光催化制备H_(2)O_(2)性能

Oxygen-rich vacancy TiO_(2)for efficient photocatalytic H_(2)O_(2) production

以纳米TiO_(2)(P25)为原料,通过固相化学还原法制备了富含氧空位(OV)的纳米TiO_(2)光催化剂(TiO_(2)-OV)。采用XRD、SEM、XPS、EPR和UV-Vis DRS光谱对TiO_(2)-OV进行了表征和测试。通过光催化实验和光电化学测试,考察了不同Na BH_(4)用量(P25用量为2.0 g时)制备的TiO_(2)-OV光催化生产H_(2)O_(2)的能力,并推测了其光催化反应机理。结果表明,TiO_(2)-OV是锐钛矿型和金红石型晶体组成的混合物。当Na BH_(4)用量为10 mg时,制备的TiO_(2)-OV-10直接带隙能(E_(g))为2.77 e V,导带(CB)电位为–0.84 e V,展示出最佳的光催化生产H_(2)O_(2)性能。在模拟太阳光照射下,H_(2)O_(2)的生产效率达到1752.80μmol/(g·h),其高效的光催化性能归因于TiO_(2)表面产生了OV,适量的OV可作为电子陷阱,从而提高了光生电子-空穴的分离效率。催化剂经4次回收循环使用后,催化性能略有下降。TiO_(2)-OV光催化生产H_(2)O_(2)的活性物种为超氧自由基、羟基自由基和空穴,CH_(3)OH在促进光载体分离及生成H_(2)O_(2)方面发挥了重要作用。

Nano TiO_(2)photocatalyst(TiO_(2)-OV)rich in oxygen vacancy(OV)was prepared from solid-state chemical reduction of nano TiO_(2)(P25),and characterized by XRD,SEM,XPS,EPR and UV-Vis DRS spectra.The photocatalytic performance of TiO_(2)-OV prepared with different amounts of Na BH_(4)(P25 2.0 g)for H_(2)O_(2)production was evaluated via photocatalysis experiment and photoelectric chemical measurement,with the photocatalytic reaction mechanism further speculated.The results showed that,a highly crystalline mixture of anatase and rutile phase,Ti O_(2)-OV prepared with 10 mg Na BH_(4)exhibited the best photocatalytic H_(2)O_(2)production performance,with the direct band gap energy(E_g)and conduction band(CB)energy of 2.77 and–0.84 e V.The production efficiency of H_(2)O_(2)reached 1752.80μmol/(g·h)under simulated sunlight irradiation,which was attributed to the fact that OV was generated on the surface of Ti O_(2),and OV with appropriate concentration could be used as an electron trap,thus improving the separation efficiency of photogenerated electron-hole.After 4 times of recycling,TiO_(2)-OV displayed slight reduction in the catalytic performance.The active species of H_(2)O_(2)photocatalyzed by TiO_(2)-OV were superoxide radical,hydroxyl radical and hole.In addition,CH_(3)OH played an important role in promoting photocarrier separation and generating H_(2)O_(2).