Nanolayered Ti₃C₂ and SrTiO₃ Composites for Photocatalytic Reduction and Removal of Uranium(VI)

Abstract

Given its promising electron transportation ability, excellent electrical conductivity, and larger work function (6.2 eV) disclosed by density functional theory calculations, MXene material, O-terminated Ti 3 C 2 has the potential to serve as a perfect cocatalyst. Herein, a novel Ti 3 C 2 /SrTiO 3 heterostructure based on partly superficial oxidation from precursor multilayered Ti 3 C 2 is developed as a photocatalyst for efficiently photocatalytic reduction and removal of U(VI). Specifically, the composite of 2 wt % Ti 3 C 2 /SrTiO 3 (0.02 Ti 3 C 2 / SrTiO 3 ) exhibits an excellent photocatalytic UO 2 2+ removal rate of 77%, which is nearly 38 times higher than that of the pristine SrTiO 3 . The enhanced photocatalytic performance of 0.02 Ti 3 C 2 /SrTiO 3 is systematically identified by photoluminescence spectroscopy, UV−vis diffuse reflectance spectroscopy, Raman spectroscopy, and electrochemical characterizations. The multilayered Ti 3 C 2 as a cocatalyst can facilitate the charge transportation and inhibit the recombination of electrons in the conduction band. This work establishes the enticing potential for developing doped perovskite oxide crystals based on the MXene Ti 3 C 2 with sun-light responsivity for improving solar energy utilization.

Recent Advances in Functional 2D MXene‐Based Nanostructures for Next‐Generation Devices

“…Recent research studies have shown that MXenes have promising potential for photocatalytic applications, due to some distinct properties: i) the high carrier mobility in MXene-based system efficiently promoting the separation and migration of photogenerated electron-hole pairs; ii) the tunable band gap of MXenes by altering their surface chemistries, for example, the terminated -F, -O, or -OH groups, or the arrangements of surface groups; iii) the abundant surface groups with more active sites on the surface of MXene. [178][179][180] It is noted that Ti 3 C 2 T x has already been employed as an efficient co-catalyst in g-C 3 N 4 , [181][182][183][184] Bi 2 WO 6 , [185] BP, [178] AgInS 2 , [65,186] SrTiO 3 , [187] hematite, [154] , anatase, [179,188,189] and so on, to further enhance their photocatalytic performance. For example, in 2018, the 2D MXene Ti 3 C 2 T x /2D g-C 3 N 4 nanosheet heterostructures were rationally designed and successfully synthesized by calcination of bulk Ti 3 C 2 and urea, where urea not only acts as the gas template to process the exfoliation of Ti 3 C 2 into Ti 3 C 2 T x nanosheets, but also as the precursor of g-C 3 N 4 to obtain 2D MXene Ti 3 C 2 T x /2D g-C 3 N 4 nanosheet heterostructures.…”

Enhanced Photocatalytic Reduction of U(VI) on SrTiO3/ g‐C3N4Composites : Synergistic Interaction

“…The preparation process of STO/CN composites included: i) synthesis of TiO 2 : 3 mL C 12 H 28 O 4 Ti was added into the mixture of 50 mL ethanol and acetonitrile (V/V = 3 : 2). Then 2.73 mL H 2 O and 1.26 mL NH 3 • H 2 O were added into the mixture under vigorous stirring for 12 h. TiO 2 was obtained by centrifuging, thoroughly rinsing with ethanol and deionized water for 3 times, and freeze-drying for 24 h; ii) synthesis of SrTiO 3 : [33] the as-prepared TiO 2 and Sr(NO 3 ) 2 (mol ratio of 1 : 1) were slowly added into 50 mL of 2 mol/L NaOH under stirring for 15 min. Then the resulting mixture was heated at 140 °C for 4 h under Teflon-lined autoclave for crystallization.…”

“…The combination of SrTiO 3 with other semiconductors can effectively inhibit the recombination of electron‐hole. Thus, various perovskite‐based composites (SrTiO 3 /Ti 3 C 2 [33] ) have been investigated nowadays. Deng et al [33] .…”

“…The combination of SrTiO 3 with other semiconductors can effectively inhibit the recombination of electron-hole. Thus, various perovskite-based composites (SrTiO 3 /Ti 3 C 2 [33] ) have been investigated nowadays. Deng et al [33] found that the photocatalytic reduction of U(VI) on Ti 3 C 2 /SrTiO 3 (77 %) was 38.5 times that of the pure SrTiO 3 due to the enhanced charge transfer of multilayer Ti 3 C 2 as a co-catalyst, which inhibited the recombination of photogenerated electrons and holes.…”

In situ Preparation of Chitosan/ZIF-8 Composite Beads for Highly Efficient Removal of U(VI)

“…Therefore, from the perspective of environmental protection and human health, it is particularly important to recover uranium efficiently from aqueous solution. At present, many techniques for uranium recovery from aqueous solution have been developed, such as photocatalytic method (Li Z. J. et al, 2017; Deng et al, 2019), chemical extraction (Sadeghi et al, 2012; Carboni et al, 2013; Wang et al, 2015), chemical flocculation method (Newsome et al, 2015), and adsorption method (Huang et al, 2018). Among these, adsorption method is one of the most extensive technologies because of low cost, simple operation, high efficiency, and good removal effect (Li et al, 2018a; Wang L. et al, 2018).…”