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Front. Chem. | doi: 10.3389/fchem.2018.00037

Ti4O7/g-C3N4 visible light photocatalytic performance on hypophosphite oxidation: Effect of annealing temperature

Wei Guan1, Gaoge Sun2, Lei Yin3,  Zhenghua Zhang2 and  Shichao Tian4*
  • 1Chongqing Key Laboratory of Environmental Materials & Remediation Technologies, Chongqing University of Arts and Sciences, China
  • 2Department of Chemistry, Tsinghua University, China
  • 3Heibei Yinfa Meifute Environmental Engineering Co., Ltd, China
  • 4Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute, China

The oxidation of hypophosphite to phosphate is the key to recover the phosphorus resource from the hypophosphite wastewater. In the present work, Ti4O7/g-C3N4 composites were synthesized at two different temperatures (100 and 160 °C) and their performance on photocatalytic oxidation of hypophosphite under visible light irradiation and the corresponding mechanism were evaluated. A hydrolysis method using g-C3N4 and Ti4O7 was applied to synthesize the Ti4O7/g-C3N4 composites with their hybrid structure and morphology confirmed by XRD, SEM and XPS. The annealing temperature significantly affected the photocatalytic performance of Ti4O7/g-C3N4 that the 160-Ti4O7/g-C3N4 composite (fabricated at 160 °C) showed the highest oxidation efficiency of hypophosphite of 81% and the highest photocatalytic oxidation rate of 0.467 h-1 comparing with the 100-Ti4O7/g-C3N4 composite (fabricated at 100 °C) and pure g-C3N4. The enhanced photocatalytic performance of 160-Ti4O7/g-C3N4 could be ascribed to the effective charge separation and enhanced photoabsorption efficiency. Additionally, electron spin resonance (ESR) results showed that hydroxyl radicals and superoxide anion radicals were mainly responsible to the oxidation of hypophosphite with superoxide anion radicals accounting for a more significant contribution. Moreover, Ti4O7/g-C3N4 photocatalysts showed the remarkable stability in the repetitive experiments.

Keywords: Graphitic carbon nitride, sub-stoichiometric titanium oxides, Hypophosphite, Hydroxyl radicals, Superoxide anion radicals

Received: 04 Dec 2017; Accepted: 14 Feb 2018.

Edited by:

Fan Dong, Chongqing Technology and Business University, China

Reviewed by:

Michael Nolan, University College Cork, Ireland
Hongwei Huang, China University of Geosciences, China  

Copyright: © 2018 Guan, Sun, Yin, Zhang and Tian. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: PhD. Shichao Tian, Tsinghua-Berkeley Shenzhen Institute, Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Shenzhen, 518055, China,