Synergetic effects of lanthanum, nitrogen and phosphorus tri-doping on visiblelight photoactivity of TiO_2 fabricated by microwave-hydrothermal process

• Published in: 中国稀土学报：英文版 Vol. 34; no. 6; pp. 604 - 613
• Main Author: 姜洪泉 刘彦铎 李井申 王海燕
• Format: Journal Article
• Language: English
• Published: 2016
• Subjects: earths; effect; microwave-hydrothermal; photoactivity; rare; synergetic; TiO_2; tri-doping; visible-light
• ISSN: 1002-0721; 2509-4963

Effects of La, N, and P doping on the structural, electronic and optical properties of TiO_2 synthesized from TiCl_4 hydrolysis via a microwave-hydrothermal process were investigated by X-ray diffraction, transmission electron microscopy, N_2 adsorption-desorption isotherm, X-ray photoelectron spectroscopy, electron paramagnetic resonance, UV-vis absorbance spectroscopy, photoelectrochemical measurements, and photoluminescence spectroscopy. The results showed that the presence of La in the tri-doped TiO_2 played a predominant role in inhibiting the recombination of the photogenerated electrons and holes. The existence of the substitutional N, interstitial N, and oxygen vacancies in TiO_2 lattices led to the band gap narrowing. It was P-doping rather than La or N doping that played a key role in inhibiting both anatase-to-rutile phase transformation and crystal growth, in stabilizing the mesoporous textural properties, and in increasing the content of surface bridging hydroxyl. Moreover, the tri-doping significantly enhanced the surface Ti^（4＋）-O^（2-）-Ti^（4＋）-O^（-·） species. All above-mentioned factors cooperated to result in the enhanced photoactivity of the tri-doped TiO_2. As a result, it exhibited the highest photoactivity towards the degradation of 4-chlorophenol（4-CP） under visible-light irradiation among all samples, which was much superior to commercial P25 TiO_2.