Enhancement of photocatalytic bromate reduction by TiO2 coupled with Ti3C2MXene as efficient non-noble cocatalyst: Performance and mechanism. Issue 1 (February 2022)

• Record Type: Journal Article
• Authors: Tang, Shasha; Yao, Jie; Liu, Hongyuan; Zhang, Yan
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 1(2022)
• Publication Date: 2022-02
• Subjects: Ti3C2 -- MXene -- Noble-metal-free cocatalyst -- Bromate removal -- Photocatalysis -- Charge carries separation; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2021.107099
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: Although considered as a promising candidate for photocatalytic bromate reduction, TiO2 is restricted by its fast recombination of photo-induced charge carriers. In this paper, a series of efficient photocatalysts (TiO2 /TC) were prepared by coupling commercial titania (P25) with titanium carbide MXene (Ti3 C2 ) via a simple hydrothermal method, where Ti3 C2 was utilized as a noble-metal-free cocatalyst. Batch experiments of photocatalytic bromate removal by TiO2 /TC composites were conducted under UV irradiation. Its performance and mechanism were also investigated. The results showed that more than 95% of bromate could be removed by TiO2 /TC-1 composite (Ti3 C2 and P25 in a mass ratio of 1%) in 15 min, and its removal rate was 4.87 times higher than that of pure P25. The photocatalytic reduction of bromate by TiO2 /TC was an interfacial reaction, and bromide was the main product. The greatly improved activity of TiO2 /TC composites was attributed to the improved separation efficiency of photogenerated charge carriers and narrower band gap. TiO2 /TC-1 composite exhibited a longer lifetime (6.05 ns) of electron-hole pairs than pristine P25 (4.31 ns). Moreover, due to its excellent electrical conductivity, Ti3 C2 functioned as "an electron sink" to accumulate photoinduced electrons from the excited P25. And the Schottky barrier formed in the tight Ti3 C2 -P25 interface provided a unidirectional channel for electron transfer, facilitating the separation of electron-hole pairs. In addition, TiO2 /TC-1 composite had a good stability in bromate removal. This work highlights the potential of Ti3 C2 as a noble-metal-free photocatalytic cocatalyst and explores the possible expansion of the application of MXene. Graphical Abstract: ga1 Highlights: TiO2 /TC composites exhibit excellent photocatalytic activity and good stability in bromate removal. The superior electrical conduction of Ti3 C2 helps to improve the separation efficiency of photoinduced charge carriers. The Schottky junction formed in the close Ti3 C2 -TiO2 interface restrains the recombination of electron-hole pairs. Synergistic effect of TiO2 and Ti3 C2 enhances the photocatalytic performance.