Synergistic Effects of Redox Couples and Oxygen Vacancies Improve the Tetracycline Degradation Property of La₂NiMnO₆

Abstract

Improving the e − and h + separation efficiency and promoting the production of more radicals is the key to improving the degradation efficiency of catalytic degradation of antibiotics. On the other hand, intermediate analysis of antibiotics in the dark adsorption and light irradiation process is very important to clarify the entire antibiotic degradation pathway. Here, the La 2 NiMnO 6 (LNMO) catalyst was prepared by the sol−gel method and the calcination method. By changing the calcination temperature (800, 900, and 1000 °C), the LNMO-based catalysts were successfully formed, abbreviated as L-800, L-900, and L-1000. XPS measurements demonstrated the presence of Mn 4+ , Mn 3+ , Mn 2+ , and oxygen vacancies (OVs) in the LNMO-based catalysts. Analysis of PL, PC, EIS, and TR-PL demonstrated that L-900 had the highest separation efficiency and fastest carrier mobility. The LNMObased catalysts were used to degrade tetracycline (TC). With the optimized catalyst L-900, the decomposition rate of TC reached 99.57% in 120 min. The entire TC degradation pathway was analyzed according to LC−MS measurements. Radical trap experiments and ESR technology revealed that the synergistic effect of Mn 4+ /Mn 3+ , Mn 4+ /Mn 2+ , and OVs not only effectively separated e − and h + but also facilitated the formation of superoxide radicals ( • O 2 − ) to accelerate TC degradation. Radicals • OH, h + , and • O 2 − all contributed to TC deterioration in increasing order of importance. In addition, XPS measurements of the L-900 catalyst before and after use indicated that Mn 4+ /Mn 3+ , Mn 4+ /Mn 2+ , and OVs were not reactants but mediators of e − and h + . Finally, the mechanism of TC degradation with the LNMO-based catalysts was discussed. This work provided new material for TC degradation in the wastewater.

Fabrication of a Covalent Organic Framework-Based Heterojunction via Coupling with ZnAgInS Nanosphere with High Photocatalytic Activity

“…Photocatalysis, as a sunlight-driven green technique, has been identified as one of the most promising solutions for removal of organic pollutants. − Generally, a superior photocatalyst requires sufficient sunlight absorbance, particularly in the visible-light range, and the effective separation and utilization of the photogenerated charge carriers. To this point, many photocatalysts have been developed for the degradation of organic pollutants.…”

High activity in the dry reforming of methane using a thermally switchable double perovskite and in situ generated molecular level nanocomposite

“…Zhang et al have reported the effect of calcination temperature on the surface area of La 2 NiMnO 6 synthesized via the sol–gel method. 52 The surface areas are found to be low and fall in the range of 2.70–2.86 m 2 g −1 depending of the annealing temperature (800–1000 °C). Qu et al have also reported low surface areas (8–14 m 2 g −1 ) for sol–gel synthesized La 2 NiMnO 6 and La 2− x Sr x NiMnO 6 .…”

“…The surface area of the as-prepared LNMnO is comparatively larger (34 vs. 2.7 m 2 g −1 ) in comparison with the earlier reports. 52,53…”

Fabrication of a Carbonized Cellulose Nanofibrils/Ti3C2Tx MXene/g-C3N4 Heterojunction for Visible-Light-Driven Photocatalysis

“…Through the above-mentioned pathways, the obtained products were further oxidized and generated ring-opening products such as P12 ( m / z = 249), P13 ( m / z = 231), P14 ( m / z = 218), P15 ( m / z = 175), P16 ( m / z = 167), and P17 ( m / z = 85). Finally, these products would be further decomposed into small molecules such as CO 2 , H 2 O, and NH 4 + …”

“…Finally, these products would be further decomposed into small molecules such as CO 2 , H 2 O, and NH 4 + . 44 ■ CONCLUSIONS Herein, a carbonized CNFs/Ti 3 C 2 T x MXene/g-C 3 N 4 (CMCN) composite as a photocatalyst was prepared through the one-step calcination of solutions of CNFs/Ti 3 C 2 T x and urea, in which g-C 3 N 4 was generated in situ from urea, forming Ti 3 C 2 T x MXene/g-C 3 N 4 , promoting the separation of Ti 3 C 2 T x MXene via releasing NH 3 , and constructing heterostructures. The as-prepared CMCN was explored in the photocatalytic degradation of MB, RhB, and TC under visible-light irradiation.…”