Graphene-BiFeO 3 composites are synthesized through a one-pot hydrothermal method and their photocatalytic performances are investigated under visible light irradiation. Bandgap engineering of BiFeO 3 -graphene composites is achieved by simply adjusting the concentration of OH groups during the hydrothermal treatment. XPS and Raman analysis indicate that enhanced coupling between BiFeO 3 nanoparticles and graphene is achieved by the formation of Fe-O-C bonds, which is mediated by OH groups adsorbed on the surface of graphene. The band gaps of the composites could be successfully tuned from 1.78 eV-2.24 eV, giving rise to high photocatalytic performance under visible light irradiation.This may be of significance in understanding the mechanism of the coupling between graphene and semiconductor oxides which are currently being intensively investigated as photocatalysts.
We report an inducible epitope imprinting strategy that as a template, a flexible peptide chain can have a disordered-to-ordered conformational change by suitable inducement through a molecular imprinting procedure, and the formed nanoparticles can, in turn, remold the original peptide into the expected conformation and specifically bind to the corresponding protein.
Controllable synthesis of Prussian blue nanoparticles (PBNPs) is significant for their various applications. Further, exploration on the growth process of PBNPs (a kind of nanoparticle which usually undergoes an extremely complicated formation process) is instructive for controllable synthesis and will be an important supplement for crystallization theory. Herein, we developed a facile method to precisely and widely control the size and crystallinity of PBNPs. By simply tuning the prior addition volume of ferric chloride and citric acid mixture combining a double injection reaction, particles with a hydrodynamic size ranging from 120 to 40 nm were synthesized. Meanwhile, the crystallinity of the particles reduced as their size decreased. Unlike the common cognition that generation of PBNPs undergoes a nonclassical aggregation process, our results demonstrated that reaction rate dominated classical nucleation and nuclei enlargement, and the subsequent crystallization contributed to the formation of PBNPs. By carefully studying the crystallography state and transformation relationship of the as-prepared particles, PBNPs were generally divided into three categories: highly crystalline, partly crystalline, and highly amorphous PBNPs. Spectroscopy, enzymology, and magnetic measurements confirmed the size-and crystallinity-dependent physicochemical properties of the PBNPs. Smaller and amorphous PBNPs exhibited remarkably stronger peroxidase-like activity, catalase-like activity, and T 1 -weighted magnetic resonance imaging (MRI) ability, suggesting their great potential in the application of multienzyme catalysis and MRI.
The Briggs−Rauscher reaction is a popular demonstration to illustrate chemical oscillations in laboratories, classrooms, and public seminars because of its simplicity and visual appeal. Here, we adapt the Briggs−Rauscher reaction to present reaction−diffusion−convection patterns in the undergraduate general or physical chemistry laboratory. By maintaining the ratio between malonic acid and potassium iodate concentrations as 0.2 in an uncovered Petri dish, sequential patterns (transient dendritic patterns and rotating dendritic patterns) can be observed, which are induced by the interaction of reaction, diffusion, and convection. This beautiful demonstration captures students' attention and inspires reflection and discussion about similar phenomena in nature as well as the wealth of behaviors in systems far from equilibrium.
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