Pure perovskite LnFeO3 (Ln = La, Pr−Tb) hollow spheres with porous shell and solid spheres (Ln = Dy−Yb, Y) have been successfully synthesized via calcination of a Ln-Fe citrate complex precursor, which was prepared via a convenient and effective hydrothermal method. The reaction parameters to obtain the Ln-Fe citrate complex with Ln/Fe = 1:1 can be calculated using a diagram of reaction species distribution in the solution. The calculated value was coincident well with the experimental one. The composition and the thermal decomposition processes of the Ln-Fe citrate complex were investigated carefully, using elemental analysis, inductively coupled plasma analysis (ICP), energy-dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The formation mechanism of the Ln-Fe citrate complex hollow spheres was proposed as an acidic digestion ripening process. Furthermore, all 13 pure-phase LnFeO3 microspheres had an excellent catalytic performance for the NO + CO reaction. The experimental results showed that the completed conversion of NO and specific selectivity of N2 were achieved, which could be comparable with the noble metal catalysts and better than that of LnFeO3 nanoparticles synthesized via the Pechini process. In addition, the LnFeO3 microspheres exhibited good chemical stability and almost invariable catalytic activity during the lifetime test lasting for 96 h.
Mesoporous beta-Ni(OH)(2) synthesized by a soft template method as a cathode material in a nickel based battery can provide higher specific discharge capacity in comparison with other micro/nanostructures.
This work reports a simple and effective method to prepare polyaniline (PANI) nanotubes with rectangular or circular cross section and hollow microspheres by using basic amino acids L-lysine or L-arginine as dopants and pH buffer agents, respectively. The research reveals that the pH value of the reaction solution at the beginning stage is a crucial factor to form PANI microstructures. The L-lysine and L-arginine have isoelectric point 9.74 and 10.76, which can maintain reaction solution at high pH value at the beginning reaction and assist aniline to couple in ortho-position forming phenazine unit in the oligomer chain. The oligomer produces rectangular nanorods or microspheres by interaction. These oligomer microstructures act as templates for further polymerization to form PANI rectangular nanotubes and hollow microspheres. Decreasing the concentration of the basic amino acid or using acidic amino acid, the round nanotubes are formed. This method provides a simple route to prepare PANI microstructures with different morphologies without any foreign template or surfactant, and raises a new view on the polymerization process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.