Nanorod bundle-like silver cyanamide nanocrystals for the high-efficiency photocatalytic degradation of tetracycline

Nano-sized aggregate Ti3C2-TiO2 supported on the surface of Ag2NCN as a Z-scheme catalyst with enhanced visible light photocatalytic performance

Exposing the photocatalyst's highly active facets and hybridizing the photocatalyst with suitable cocatalysts in the proper spot have been recognized as strong methods for high-performance photocatalysts. Herein, Ag2NCN/TiO2-Ti3C2 composites were synthesized by applying simple calcination and physically weak interaction deposition processes to obtain an excellent photocatalyst for Rhodamine B (Rh B) degradation when exposed to visible light. The findings from the experiments reveal that the Ag2NCN/TiO2-Ti3C2400 composite exhibited an outstanding photocatalytic rate in 80 min, with the highest Rh B degradation rate (k = 0.03889 min-1), which was 16 times higher than that of pure Ag2NCN (k = 0.00235 min-1) and 2.2 times higher than that of TiO2-Ti3C2400 (k = 0.01761 min-1). The results from the following factors: (i) the powerful interfacial contact created by the in situ formation of TiO2, and the superior electrical conductivity of Ti3C2 that makes carrier separation possible; (ii) TiO2 with electron-rich (101) facets are deposited on the surface of Ag2NCN, significantly reducing charge carrier recombination by trapping photoelectrons; (iii) a Z-type heterojunction is constructed between nanosize aggregate Ti3C2-TiO2 and Ag2NCN with non-metal Ti3C2 as the solid medium, improving the transfer and separation of photogenerated charges and inhibiting the recombination of electrons and holes. Additionally, the redox ability of the composite photocatalyst is enhanced. Furthermore, the analyses of active species showed that photogenerated superoxide radicals and holes were the principal active agents inside the photodegradation of Rh B. Moreover, the composite exhibited outstanding photo-stability.

Ag2NCN anchored on Ti3C2Tx MXene as a Schottky heterojunction: enhanced visible light photocatalytic efficiency of rhodamine B degradation

The quick charge recombination of light-generated electrons and holes severely restricts the photocatalytic applications of single semiconductors. Here, a straightforward electrostatically driven self-assembly technique was used to construct an Ag₂NCN/Ti₃C₂T_x Schottky heterojunction, which was then used to degrade Rhodamine B (RhB) in the illumination of visible light. The findings from the experiments revealed that as a cocatalyst, Ti₃C₂T_x significantly suppresses the recombination rate and broadens visible absorptivity to improve Ag₂NCN photocatalytic efficiency. The optimized Ag₂NCN/Ti₃C₂T_x (AT2) composite exhibited an outstanding photocatalytic rate in 96 min, with the highest RhB degradation rate (k = 0.029 min^-1), which was around fifteen times that of pure Ag₂NCN (k = 0.002 min^-1). Furthermore, the trapping-agent experiment showed photogenerated superoxide radicals and holes were the principal active agents inside the photodegradation of RhB. Compared with Ag-based semiconductors, the composite exhibited outstanding photostability, highlighting its excellent potential for application in visible-light photocatalysis.

Catalytic ozonation of phenol by ZnFe2O4/ZnNCN: performance and mechanism

A novel magnetic catalyst was synthesized and applied in heterogeneous catalytic ozonation process. The ZnFe₂O₄/ZnNCN material was synthesized by hydrothermal and high-temperature calcination method and characterized by XPS, XRD, FTIR, VSM, and SEM techniques. In the system of O₃/ZnFe₂O₄/ZnNCN, the removal rates of phenol and chemical oxygen demand (COD) reached 93% and 43% at 60 min. Further analysis shows that ZnFe₂O₄/ZnNCN has a significant catalytic effect on O₃, which is demonstrated by the first-order kinetic constant being 1.93 times than O₃ alone. The catalyst exhibits excellent cycling stability during repeated catalytic ozonation process and can be fully recycled under an applied magnetic field. The role of hydrogen peroxide (H₂O₂) and surface hydroxyl groups was investigated, and a mechanism for catalytic ozonation was proposed. This work not only builds an efficient catalytic ozonation system, but also provides a potential modification strategy for spinel oxides.