Synthesis, Characterization of g-C3N4/SrTiO3 Heterojunctions and Photocatalytic Activity for Organic Pollutants Degradation

Abstract

Perovskite-structure SrTiO3 (STO) and graphitic carbon nitride (g-C3N4, CN) have attracted considerable attention in photocatalytic technology due to their unique properties, but also suffer from some drawbacks. The development of composite photocatalysts that combine properties of the individual semiconductors with enhanced charge separation is the current major trend in the photocatalysis field. In this study, SrTiO3/g-C3N4 (CNSTO) composites with different ratios (10, 20, 30, 40 and 50% g-C3N4) were prepared with a sonication mixing method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 porosimetry, Fourrier transform infra-red spectroscopy (FT-IR), UV-Vis diffuse reflectance (DRS) and dynamic light scattering (DLS). STO spherical particles were successfully loaded on the g-C3N4 planes forming heterojunction composite materials. The photocatalytic activity was tested against the degradation of methylene blue (MB) dye under simulated solar light (SSL) irradiation following first-order kinetics. The photocatalytic activity followed the trend: 20CNSTO > 30CNSTO > 40CNSTO > 50CNSTO ≈ 10CNSTO, in accordance with the amount of •OH radicals determined by fluorescence spectroscopy. A Z-scheme mechanism was proposed for the enhanced photocatalytic degradation of MB as evidenced by trapping experiments with scavengers. Finally, significant stability and reusability was exhibited, indicating that such composites are of potential interest for photocatalytic treatments under sunlight irradiation.

Photocatalytic Treatment of Pharmaceuticals in Real Hospital Wastewaters for Effluent Quality Amelioration

“…Furthermore, the experiments under dark conditions which were performed in order to establish the adsorption-desorption equilibrium of the target compounds showed limited adsorption of the target compounds on the catalyst's surface i.e., less than 9%, at equilibrium (30 min). These very low adsorption phenomena are due to the catalysts small specific surface areas, since they display 50, 35 and 32 m 2 g −1 for TiO 2 , CN and 20CNSTO, respectively [42]. The photocatalytic efficiency of AMS and CBZ was significantly enhanced in the presence of CN, showing a degradation of 98% (t1/2 = 22.5 min) and 86% (t1/2=29.9 min), respectively after 90 min of irradiation.…”

“…The other two catalysts were the graphitic carbon nitride (g-C 3 N 4 , CN) (BET SSA 35 m 2 g −1 , particle size of 25 nm, Eg = 2.82 eV) and the heterojunction g-C 3 N 4 /SrTiO 3 with g-C 3 N 4 to SrTiO 3 ratio of 20% (20CNSTO) (BET SSA 32 m 2 g −1 , particle size 27.6 nm, Eg values 2.80 and 3.28 in respect to g-C 3 N 4 and SrTiO 3 , respectively). The synthesis and characterization of these two materials is described elsewhere [42].…”

Photoinduced electronic and ionic effects in strontium titanate

“…Since their experiments, related semiconductors such as ZnO [203][204][205][206], SnO 2 [207][208][209][210][211], Fe 2 O 3 [212][213][214][215], and STO attracted a lot of interest as photoanodes and were studied extensively throughout the last decades. Among others, STO became one of the best investigated compounds and applications in the field of photocatalytic overall water splitting [216-225], applications for H 2 evolution [226][227][228][229][230][231][232][233][234][235][236][237], CO 2 conversion [238][239][240], inorganic/organic pollutant, NO x , SO x and dye degradation [233,[241][242][243][244][245][246][247][248][249][250][251][252][253][254], N 2 fixation [255], and bacteria inactivation [256] were also reported.…”

“…The described ternary TiO 2 /STO/g-C 3 N 4 has similar applications as TiO 2 /STO heterojunctions and can be used as photocatalyst in organic pollutant degradation [242,314,320], for hydrogen production [314,323] or N 2 fixation [323]. The system can also be simplified to STO/g-C 3 N 4 [247,273,283,325]. In such a two-component system it is easier to modify the electronic structure of STO, since in a composition with only one heterojunction, the position of the band gaps can be chosen more freely.…”

Spark Plasma Sintering Treatment for Introduction of Oxygen Vacancy in Pt Dispersed SrTiO3 for Increasing Photocatalytic Water Splitting Activity

“…Among the photocatalysts studied, SrTiO 3 has been attracting much interest as the active photocatalyst and this oxide has wide band gap (3.2 eV) and high chemical stability with perovskite structure . High apparent quantum yield (>60 %) at 380 nm light is reported for Al and Mo modified SrTiO 3 .…”