Hierachical Ni@Fe₂O₃superparticles through epitaxial growth of γ-Fe₂O₃nanorods onin situformed Ni nanoplates

Abstract

One endeavour of nanochemistry is the bottom-up synthesis of functional mesoscale structures from basic building blocks. We report a one-pot wet chemical synthesis of Ni@γ-Fe2O3 superparticles containing Ni cores densely covered with highly oriented γ-Fe2O3 (maghemite) nanorods (NRs) by controlled reduction/decomposition of nickel acetate (Ni(ac)2) and Fe(CO)5. Automated diffraction tomography (ADT) of the Ni-Fe2O3 interface in combination with Mössbauer spectroscopy showed that selective and oriented growth of the γ-Fe2O3 nanorods on the Ni core is facilitated through the formation of a Fe0.05Ni0.95 alloy and the appearance of superstructure features that may reduce strain at the Ni-Fe2O3 interface. The common orientation of the maghemite nanorods on the Ni core of the superparticles leads to a greatly enhanced magnetization. After functionalization with a catechol-functional polyethylene glycol (C-PEG) ligand the Ni@γ-Fe2O3 superparticles were dispersible in water.

Synthesis of Au, Ag, and Au–Ag Bimetallic Nanoparticles Using Pulicaria undulata Extract and Their Catalytic Activity for the Reduction of 4-Nitrophenol

“…and chemical processes. The solution-based chemical methods are best suited for controlling the particle size and morphology because nucleation and growth steps can be easily monitored [ 6 , 7 , 8 , 9 , 10 ]. This requires different hazardous chemicals such as chemical reductants and capping agents to compensate the surface energy to stabilize these NPs in the nano-size regime.…”

Nickel Colloidal Superparticles: Microemulsion-Based Self-Assembly Preparation and Their Transition from Room-Temperature Superparamagnetism to Ferromagnetism

“…One of the advantages of this approach is that it can obtain independent structures that do not need to be fixed on a substrate like the case of superlattices, so it is convenient to investigate the relationships between the structure and properties of superparticles. Among various colloidal superparticles, magnetic colloidal superparticles have received a great deal of attention. ,,,− ,,− Especially in the biological and medical fields, magnetic colloidal superparticles have been shown to exhibit enhanced magnetic resonance imaging (MRI) and fluorescence imaging − and also photothermal-photodynamic therapeutic effect …”

Selective Synthesis of Monodisperse CoO Nanooctahedra as Catalysts for Electrochemical Water Oxidation

“…Much effort has been devoted to understand how particle size, ,− phase composition, ,, and morphology , can be tuned by a careful choice of solvents and capping agents. Morphology control is an important goal because facet-dependent reactivity and stability of cobalt oxides have been reported for the oxygen evolution reaction (OER), , which has a slow kinetics and poor energy efficiency due to the overpotential associated with the four-electron reaction 2H 2 O = 4H + + O 2 + 4e – (in acidic media) or 4OH – = 2H 2 O + O 2 + 4e – (in alkaline media).…”

“…The organic solvent prevents the precipitation of metal hydroxides, and the thermolysis of molecular precursors leads to a controlled formation of particles with specific size, morphology, phase selectivity, crystallinity, and surface coordination. 45 Much effort has been devoted to understand how particle size, 42,46−48 phase composition, 45,49,50 and morphology 48,51 can be tuned by a careful choice of solvents and capping agents. Morphology control is an important goal because facetdependent reactivity and stability of cobalt oxides have been reported for the oxygen evolution reaction (OER), 52,53 which has a slow kinetics and poor energy efficiency due to the overpotential associated with the four-electron reaction 2H 2 O = 4H + + O 2 + 4e − (in acidic media) or 4OH − = 2H 2 O + O 2 + 4e − (in alkaline media).…”