AUTHOR=Li Jian , Wang Yufei , Guo Fanhui , Chen Juan , Wang Jinxi , Fan Xiaoyong , Li Baoning , Verma Santosh Kumar , Wei Qingbo , Yan Long , Wu Jianjun 

TITLE=Efficient catalytic degradation of methylene blue by a novel Fe3+-TiO2@CGS three-dimensional photoelectric system

JOURNAL=Frontiers in Chemistry

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.1065003

DOI=10.3389/fchem.2022.1065003

ISSN=2296-2646

ABSTRACT=<p>In this study, a novel three-dimensional photoelectric system was designed and constructed for the degradation of methylene blue (MB) <italic>via</italic> photocatalysis, electrocatalysis, and photoelectric catalysis. To this end, a Ti/RuO<sub>2</sub>-IrO<sub>2</sub>-SnO<sub>2</sub>-CeO<sub>2</sub> electrode was prepared <italic>via</italic> a thermal oxidation coating method and used as a dimensionally-stable anode (DSA). The cathode was made of a titanium sheet with Fe<sup>3+</sup>-doped TiO<sub>2</sub> loaded on coal gasification slag (CGS) (Fe<sup>3+</sup>-TiO<sub>2</sub>@CGS) as a photocatalyst. The factors affecting the degradation efficiency, such as the supporting electrolyte, current density, and initial pH were systematically investigated. The results revealed Fe<sup>3+</sup>-TiO<sub>2</sub>@CGS three-dimensional photoelectric system exhibiting efficient synergistic performance of photocatalysis and electrocatalysis with a synergistic factor of 1.11. Photo-generated holes (h<sup>+</sup>) were generated by light irradiation and direct anodic oxidation. Furthermore, hydroxyl radicals (HO·) radicals were induced <italic>via</italic> other pathways. Such active species showed highly-oxidizing abilities, beneficial to the degradation of methylene blue (MB). The representative Fe<sup>3+</sup>-TiO<sub>2</sub>@CGS three-dimensional photoelectric system showed super high degradation efficiency at pH 11 and current density of 18.76 mA cm<sup>−2</sup>. Using NaCl as a supporting electrolyte, the degradation yield reached 99.98% after 60 min of photoelectrical treatment. Overall, the novel Fe<sup>3+</sup>-TiO<sub>2</sub>@CGS three-dimensional photoelectrical system looks very promising for the highly efficient catalytic degradation of organic contaminants.</p>