Nitrogen‐Enriched Fe₃O₄@Carbon Nanospheres Derived from Fe₃O₄@3‐Aminophenol/Formaldehyde Resin Nanospheres Based on a Facile Hydrothermal Strategy: Towards a Robust Catalyst Scaffold for Platinum Nanocrystals

Abstract

Robust nitrogen-enriched Fe3O4@carbon nanospheres have been fabricated as a catalyst scaffold for Pt nanoparticles. In this work, core-shell Fe3O4@3-aminophenol/formaldehyde (APF) nanocomposites were first synthesized by a simple hydrothermal method, and subsequently carbonized to Fe3O4@N-Carbon nanospheres for in situ growth of Pt nanocrystals. Abundant amine groups were distributed uniformly onto Fe3O4@N-Carbon nanospheres, which not only improved the dispersity and stability of the Pt nanocrystals, but also endowed the Pt-based catalysts with good compatibility in organic solvents. The dense three-dimensional cross-linked carbon shell protects the Fe3O4 cores against damage from harsh chemical environments, even in aqueous HCl (up to 1.0 M) or NaOH (up to 1.0 M) solutions under ultrasonication for 24 hours, which indicates that it can be used as a robust catalyst scaffold. In the reduction of nitrobenzene compounds, the Fe3O4@N-Carbon@Pt nanocatalysts show outstanding catalytic activity, stability, and recoverability.

Biomass-Derived Activated Carbon Supported Fe3O4 Nanoparticles as Recyclable Catalysts for Reduction of Nitroarenes

“…In terms of CPMs, activated carbons derived from biomass feedstocks, which are readily available in nature, are not only eco-friendly and cost-effective but also possess high porosity, good electrical conductivity, and oxygen surface functional groups and heteroatoms desirable as catalyst supports for applications in sensors, ,− catalysis, , and energy storage devices. ,, The synthesis of biomass-derived CPMs normally invokes a chemical activation process during which activating agents, such as ZnCl 2 , KOH, NaOH, or H 3 PO 4 , are introduced along with the carbon precursor. , Upon completing the subsequent carbonization treatment, the substrate was then washed with concentrated HCl to remove undesirable impurities …”

“…36,40,41 The synthesis of biomass-derived CPMs normally invokes a chemical activation process during which activating agents, such as ZnCl 2 , KOH, NaOH, or H 3 PO 4 , are introduced along with the carbon precursor. 42,43 Upon completing the subsequent carbonization treatment, the substrate was then washed with concentrated HCl to remove undesirable impurities. 44 Beetroot red (or betanin), a natural antioxidant whose color depends on pH, is usually obtained from the extract of beet juice and commonly exploited as pigment in the food industry.…”

Yolk–Shell Fe3O4@Void@N‐Carbon Nanostructures Based on One‐Step Deposition of SiO2 and Resorcinol‐3‐Aminophenol‐Formaldehyde (R‐APF) Cocondensed Resin Dual Layers onto Fe3O4 Nanoclusters

“…[ 39 ] Due to the action of heterogeneous nucleation and the electrostatic attraction of the ammonium ions adsorbed on the surface of the magnetic core, the negatively charged SiO 2 shell was coated on the surface of the Fe 3 O 4 /PAA nanoclusters by the Stöber method. Subsequently, NH 4 + ions cover negatively charged Fe 3 O 4 @SiO 2 nanospheres to balance their surface charge, which induces the negatively charged hydroxymethyl‐substituted copolymer intermediate of 3‐aminophenol, resorcinol, and formaldehyde catalyzed by OH − ions onto Fe 3 O 4 @SiO 2 nanospheres, similar to the deposition of negatively charged APF resin layer onto Fe 3 O 4 /PAA nanoclusters under alkalic environment, [ 40 ] then Fe 3 O 4 @SiO 2 @R‐APF nanospheres with the middle SiO 2 layer and the outer R‐APF resin shell were obtained. Finally, yolk–shell Fe 3 O 4 @Void@N‐Carbon nanostructures were through carbonizing the R‐APF resin and subsequent etching SiO 2 middle layer.…”