Oxygen vacancy mediated single unit cell Bi2WO6 by Ti doping for ameliorated photocatalytic performance

• Published in: Journal of colloid and interface science 2021-01, Vol.581, p.276-291
• Main Authors: Arif, Muhammad, Zhang, Min, Mao, Yue, Bu, Qingxia, Ali, Amjad, Qin, Zhong, Muhmood, Tahir, Shahnoor, Liu, Xiaoheng, Zhou, Baojing, Chen, Shen-ming
• Format: Article
• Language: English
• Subjects: Bi2WO6; Crystal defects; Oxygen vacancy; Photocatalysis; Ti-doping
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2020.07.113

[Display omitted] •Novel tetrabutyl titanate-directed single-unit-cell Ti-doped Bi2WO6 was fabricated by facile hydrothermal method.•The Ti-doping mediate crystal defects and generate surface oxygen vacancies, improving the visible light absorption.•The Ti-doping can act as surface electron scavenger sites, which enhanced the charge transfer and suppress the recombination rate.•The synergistic effect of Ti-doping and surface oxygen vacancies greatly enhance the photocatalytic performance of Ti-Bi2WO6 compared Bi2WO6.•A possible photodegradation pathway for ceftriaxone sodium was proposed and discussed. Crystal defects are crucially important in semiconductor photocatalysis. To improve the reactivity of photocatalysts and attain desirable solar energy conversion, crystal defect engineering has gained considerable attention in real catalysts. Herein, we engineered crystal defects and mediate oxygen vacancies in host Bi2WO6 crystal lattice via varying content of Ti dopant to fabricate single-unit-cell layered structure, resulting in enhanced visible-light-driven photocatalytic efficiency. Density functional theory (DFT) calculations verified that the substitution of Bi cation in the crystal structure of Bi2WO6 can induce a new defect level, and increase the density of states (DOS) at the valence band maximum, which not only improve the charge dynamic but also the electronic conductivity. Remarkably, the single-unit-cell layers Ti-doped Bi2WO6 structure casts profoundly improved photocatalytic performance towards ceftriaxone sodium degradation, Cr(VI) reduction, and particularly higher photocatalytic H2 production rate, with a 5.8-fold increase compared to bulk Bi2WO6. Furthermore, the photoelectrochemical measurements unveil that the significantly higher charge migration and charge carrier dynamic counts for the elevated photocatalytic performance. After careful examination of experimental results, it was proved that the Ti doping mediated crystal defects, and engendered oxygen vacancies are critically important for controlling the photocatalytic performance of Bi2WO6.