Temperature-dependent variations in toxicity of diamide insecticides against three lepidopteran insects.

The effect of temperature on the toxicities of four diamide insecticides (chlorantraniliprole, cyantraniliprole, flubendiamide, tetraniliprole) against three lepidopteran insects (Helicoverpa armigera, Plutella xylostella, Athetis lepigone) were determined from 15 to 35 °C by exposing third-instar larvae to dip-treated cabbage leaf. The results indicated that increase in temperature led to an increase significantly and regularly in the toxicities of the four diamide insecticides against P. xylostella and H. armigera, but not for A. lepigone. The temperature coefficients (TCs) of the four diamide insecticides increased from 15 to 35 °C. Tetraniliprole for H. armigera (+825.83), chlorantraniliprole for P. xylostella (+315.65) and cyantraniliprole for H. armigera (+225.77) exhibited high positive TCs. For A. lepigone, temperature had a positively weak or no effect on the toxicities of most of the diamide insecticides from 20 to 30 °C, but a higher effect from 30 to 35 °C. In addition, the toxicities of chlorantraniliprole, cyantraniliprole and tetraniliprole all decreased from 15 to 20 °C. This study can guide pest managers in choosing suitable ambient field temperature when spraying diamide insecticides against lepidopteran insects.

Efficient photocatalytic nitrogen fixation via oxygen vacancies in Zr-MOFs at ambient conditions.

Photocatalytic nitrogen fixation is seen to be a potential technology for nitrogen reduction due to its eco-friendliness, low energy consumption, and environmental protection. In this study, photocatalysts with abundant oxygen vacancies (Zr-naphthalene dicarboxylic acid (Zr-NDC) and Zr-phthalic acid (Zr-BDC)) were designed using 1,4-naphthalene dicarboxylic acid (H2NDC) and 1,4-phthalic acid (H2BDC) as ligands. Since the structure of H2NDC includes one extra benzene ring than H2BDC, the charge density differential of the organic ligand is probably altered. The hypothesis is proved by density function theory (DFT) calculation. The abundant oxygen vacancies of the catalyst offer numerous active sites for nitrogen fixation. Concurrently, the process of ligand-metal charge transfer facilitates photo-electron transfer, creating an active center for nitrogen reduction. Additionally, the functionalization of ligand amplifies another pathway for charge transfer, broadening the light absorption range of Metal-organic framework (MOF) and increasing its capacity for nitrogen reduction. In contrast to H2BDC, the benzene ring added in H2NDC structure acts as an electron energy storage tank with a stronger electron density difference favorable for photogenerated electron-hole separation resulting in higher photocatalytic activity in Zr-NDC. The experimental results show that the nitrogen fixation efficiency of Zr-NDC is 163.7 µmol g-1h-1, which is significantly better than that of Zr-BDC (29.3 µmol g-1h-1). This work utilizes cost-effective and non-toxic ingredients to design highly efficient photocatalysts, thereby significantly contributing to the practical implementation of green chemistry principles.

Fe/Zr-MOFs constructed by a sunlight-responsive ligand for efficient photocatalytic nitrogen fixation under ambient condition.

Photocatalytic nitrogen fixation opens new opportunities for sustainable and healthier futures, and developing effective and inexpensive photocatalysts is the key. We use the ligand 3,3',5,5'-azomellitic acid (H4abtc) to connect with Fe clusters and Zr clusters to form stable metal-organic frameworks (MOFs) Fe-abtc and Zr-abtc, both of which are responsive to visible lights for nitrogen fixation. It is worth noting that the presence of NN in the ligand makes it respond to visible lights. The tetracarboxyl group is connected to the metal cluster to form a stable structure. The field-only surface integral method verified that the ligands were successfully applied into the synthesized MOF particles, which expanded the photoresponse range and enhanced the photonic interactions of the synthesized photocatalysts compared with pure MOF particles. The best photocatalytic nitrogen fixation performance of Fe-abtc and Zr-abtc is 49.8 µmol·g(cat.)-1·h-1 and 35.7 µmol·g(cat.)-1·h-1, respectively, the apparent quantum efficiency (AQY) of the sample Fe-abtc is 0.56 %, and the reliability of the source of N element is proved by the isotope 15N2. This work provides a new idea for the design of cheap and effective MOFs for photocatalytic nitrogen fixation.