Pt、N共掺杂TiO_2在可见光下对三氯乙酸的催化降解作用

Titanium Dioxide Nanoparticles Codoped with Pt and N for Photodegradation of Cl_3CCOOH

采用溶胶-凝胶法制备了氮掺杂纳米TiO2(N-TiO2),并用光分解沉积法在N-TiO2表面负载微量金属Pt(0.5%(w)),形成铂-氮共掺杂纳米TiO2(Pt/N-TiO2).实验结果表明,Pt、N共掺杂纳米TiO2紫外可见光吸收边带较纳米TiO2红移约20nm,并在400～500nm处有弱的吸收.Pt/N-TiO2电极在可见光区的光电流约为纳米TiO2电极的6倍.以Pt/N-TiO2为催化剂,催化三氯乙酸(TCA)光降解反应,室温下经可见光照射2h后TCA降解率约为8%.N掺杂减小了TiO2的禁带能隙,使它在可见光区具有光催化活性,适量Pt掺杂抑制了光生载流子的复合,加速了电子界面传递速度,Pt、N共掺杂使两种效应相结合,进一步提高了光催化反应性能.

Nanoparticles of titanium dioxide doped with nitrogen（N-TiO2） were synthesized using sol-gel method. Nano-TiO2 codoped with platinum and nitrogen（Pt/N-TiO2） was prepared by photolysis-deposition of H2PtCl6 on N-TiO2 （0.5% （w） Pt）. The onset of the absorption spectrum of Pt/N-TiO2 has a 20 nm red-shift and a weak absorption in the wavelength region from 400 to 500 nm compared with the spectrum of the non-doped catalyst. The photocurrent of Pt/N-TiO2 electrode is five times higher than that of TiO2 electrode. The photodegradation yield of trichloroacetic acid over Pt/N-TiO2 catalyst is 8% under visible light irradiation for 2 h. Doping nitrogen in TiO2 reduces the band gap of anatase, which makes N-TiO2 possess catalytic activity in visible light region. Pt clusters precipitated on nano-TiO2 may retard the recombination of the photo-exited charge carders and improve interfacial charge transfer. Pt/N-TiO2 catalyst benefited from both of the effects.