Reduced graphene oxide modified Z-scheme AgI/Bi2MoO6 heterojunctions with boosted photocatalytic activity for water treatment originated from the efficient charge pairs partition and migration

Highly efficient removal of oxytetracycline using activated magnetic MIL-101(Fe)/γ-Fe2O3 heterojunction catalyst

A novel magnetic nanocomposite MIL-101(Fe)/γ-Fe₂O₃ was synthesized by hydrothermal method. The physical structure and chemical property of the as-obtained magnetic nanocomposite was characterized. The ability of MIL-101(Fe)/γ-Fe₂O₃ to promote photo-assisted peroxydisulfate (PDS) activation was investigated by using oxytetracycline (OTC) as the target pollutant. The results showed that the composite with a FeCl₃•6H₂O: γ-Fe₂O₃ mass ratio of 10:1 exhibited the highest degradation efficiency (up to 91.2%). Influencing factors such as pH, catalyst dosage, PDS concentration and OTC concentration on the catalytic performance of MIL-101(Fe)/γ-Fe₂O₃ were also investigated to determine the optimum conditions. More importantly, the MIL-101(Fe)/γ-Fe₂O₃ can be magnetically recovered and reused for 4 cycles. Based on radical quenching and electron spin resonance (ESR), the possible degradation mechanism of OTC in photo-assisted PDS activation (PPA) system was proposed. This research provided novel insights for the design and preparation of a new type of magnetic Fe-MOFs for environmental remediation.

pH dependent synthesis and characterization of bismuth molybdate nanostructure for photocatalysis degradation of organic pollutants

Bismuth molybdate (Bi₂MoO₆) nanostructures has attracted many researches as an advanced photocalysts for the organic contaminants. In this paper, bismuth molybdate Bi₂MoO₆ nanoparticles were synthesized using a simple hydrothermal method at varied pH (2, 4, 6, 8, and 10) for 15 h at 180 °C. The results reveal the variation pH precursor solutions have a significant impact on the morphology, phase formations, and photocatalytic activity of samples. The synthesized samples at low pH level were characterized by FESEM analysis revealing Bi₂MoO₆ nanoplates have formed while gradually convert to Bi₂MoO₆ spherical nanoparticle at high PH level as shown in energy dispersive X-ray spectroscopy (DES) peaks. The X-ray diffraction patterns reveal characteristic peaks corresponding to mixed phases of Bi₂MoO₆ and cubic Bi₄MoO₉ at high pH value. The optical absorption study exhibit Bi₂MoO₆ nanoplates absorbed visible light with blue shift when compared to the cubic Bi₄MoO₉ structures. Moreover, the photocatalytic activity results revealed that nanoplates in pH = 4 sample has excellent photocatalytic activity for degradation of rhodamine (RhB), methylene orange (MO), and phenol under visible-light irradiation (λ > 400 nm) as well as exhibit the photodegradation 90% of phenol within 300 min.

Interfacial coupling effects on adsorptive and photocatalytic performances for photoresponsive graphene-wrapped SrTiO3@Ag under UV-visible light: experimental and DFT approach

Understanding the graphene/semiconductor/metal interactions is crucial to design innovative photocatalytic materials with efficient photocatalytic activity for environmental cleanup applications. SrTiO₃ on reduced graphene oxide (rGO) with various graphene contents was successfully synthesized in this study utilizing a simple hydrothermal method, followed by decorating the surface with Ag particles by using the photodeposition process. Under UV-visible light irradiation, the resulting composites were tested for their improved photocatalytic activity to decompose methylene blue (MB). The prepared photocatalysts were characterized by XRD, SEM, EDX, DLS, FT-IR, Raman spectroscopy, and DRS. First-principle density functional theory calculations (DFT) were also carried out by using the generalized gradient approximation (GGA) and PBE functional with the addition of on-site Coulomb correction (GGA + U). The obtained SrTiO₃/rGO@Ag composites showed great improvement in the photocatalytic performances over pristine SrTiO₃. For the degradation reaction of MB, SrTiO₃/rGO_20%@Ag_4% composites yielded the best photocatalytic activity with efficacy reach 94%, which was also shown that it could be recycled up to four times with nearly unchanged photocatalytic activity.

Degradation of oxytetracycline by magnetic MOFs heterojunction photocatalyst with persulfate: high stability and wide range

Photocatalysis with persulfate (PS) is an effective method for the degradation of degrading organic pollutants. In this study, Fe₃O₄/MIL-101(Fe), a magnetic heterojunction photocatalyst, was produced using a hydrothermal method. The material coupled with PS exhibited excellent removal efficiency for oxytetracycline (OTC) (87.1%, 1 h). And it has a wide range of applications, with good removal efficiency for OTC concentrations of 30 to 70 mg/L and pH values of 3 to 9. •SO₄^- and •OH played a major role in the OTC removal reaction and there was an Fe(III)/Fe(II) cycle during the reaction. With excellent stability and recoverability, the OTC removal efficiency decreased by only 4.29% after four cycles, and the Fe leaching did not exceed 0.035 mg/L per cycle. This study provides significant insights into the removal of organic pollutants from water bodies.

Fabrication of CdS/Ti3C2/g-C3N4NS Z-scheme composites with enhanced visible light-driven photocatalytic activity

The Ti3C2 and g-C3N4NS were obtained first, and the CdS/Ti3C2/g-C3N4NS Z-scheme composites were prepared via a facile hydrothermal synthesis, and their photocatalytic properties were investigated. The g-C3N4NS with a high surface area displayed higher adsorption and degradation capacity. Compared with Ti3C2/g-C3N4NS and CdS, the visible light photocatalytic activity of CdS/Ti3C2/g-C3N4NS composites was improved. The as-synthesized CTN-4:1 composite exhibited outstanding photocatalytic performance for degradation of orange II, approximately 3.2 and 10.7 times higher than that of Ti3C2/g-C3N4NS and CdS, respectively. The fabrication of CdS/Ti3C2/g-C3N4NS Z-scheme heterostructure using Ti3C2 as electron transfer medium improved the separation ability of the photoinduced e--h+ pairs, thereby leading to the improvement of visible light-driven photocatalytic activity. This finding provides new insights into the construction of high efficiency Z-scheme heterostructure photocatalyst.