Three-Dimensional Nanostructures Formed from Morphology Controlled Synthesis of Pt Particles Based on Gas–Liquid Reaction for Electrocatalytic Application

In this paper, platinum (Pt) nanomaterials with controlled morphologies are grown on the surface of flowerlike manganese dioxide (MnO₂) respectively based on gas–liquid reaction. Then flowerlike three-dimensional (3D) nanostructures are formed, with successful synthesis of corresponding Pt/MnO₂ nanocomposites. The obtained nanocomposites are characterized by scanning electron microscopy, energy-dispersive X-ray spectrum, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. In addition, an interesting color-change phenomenon appeared with the Pt nucleation and growth progress which may be due to variation of the Mn valence state triggered by the reduction of Pt. This phenomenon can be used for naked-eye observation of materials’ growth states which is beneficial for investigation of synthetic mechanisms. At last, the Pt/MnO₂ 3D nanostructure exhibits perfect electrocatalytic properties toward oxidation of methanol. The four kinds of Pt/MnO₂ composites are all used for electrochemical catalytic sensing of methanol respectively which indicates that the morphology of nanomaterials determines the catalytic properties. This research provides a new platform for controllable synthesis of nanomaterials and investigation of electrocatalysis based on morphology controlled nanomaterials

Synthesis of Silver Nanoparticles Based on Hydrophobic Interface Regulation and Its Application of Electrochemical Catalysis

It has been shown that the aggregation of particles is a big challenge in synthetics progress due to the Brownian movement and van der Waals potential among the particles. Thus, how to avoid aggregation to synthesize nanoparticles with homogeneous morphology has been greatly impressed by considerable researchers and many strategies have been implemented to solve the problem in recent years. In this paper, a novel method for silver nanoparticles (AgNPs) synthesize based on the regulation of hydrophobic interface was proposed, studies showed that in the presence of hydrophobic polyhedral oligomeric silsesquioxane (POSS), AgNPs with homogeneous morphology grown on interface between GO and silver nitrate (AgNO₃) solution through a kind of common chemical reduction, and aggregation of AgNPs is avoided effectively without any protection under room temperature. The possible mechanism is discussed and the obtained AgNPs–POSS/rGO nanocomposites are used to fabricate electrochemical sensor for nitrobenzene, <i>p</i>-nitroaniline, and <i>p</i>-nitrobenzoic acid sensing. The composites have good ability to catalyze nitroaromatic compounds with the broad linear ranges of 0.5–155 ppm, 0.1–77 ppm, and 0.05–330 ppm and the low detection limits of 0.1, 0.05, and 0.02 ppm, respectively. The novel method provides a new platform for the synthesis of nanomaterials, the idea that changing hydrophobic/hydrophilic property of substrate material for growth of namomaterial may open up the traditional synthetic minds, and it will be expected to synthesize other optical, electronic, and magnetic nanomaterials

Controllable Synthesis of Formaldehyde Modified Manganese Oxide Based on Gas–Liquid Interfacial Reaction and Its Application of Electrochemical Sensing

Controllable synthesis of manganese oxides was performed via a simple one-step synthetic method. Then obtained manganese oxides which exhibit flower-like, cloud-like, hexagon-like, and rod-like morphologies were modified by formaldehyde based on a simple self-made gas–liquid reaction device respectively and the modified manganese oxides with coral-like, scallop-like and rod-like morphology were synthesized accordingly. The obtained materials were characterized and the formation mechanism was also researched. Then the modified manganese oxides were used to fabricate electrochemical sensors to detect H₂O₂. Comparison of electrochemical properties between three kinds of modified manganese oxides was investigated and the best one has been successfully employed as H₂O₂ sensor which shows a low detection limit of 0.01 μM, high sensitivity of 162.69 μA mM^–1 cm^–2, and wide linear range of 0.05 μM–12.78 mM. The study provides a new method for controllable synthesis of metal oxides, and electrochemical application of formaldehyde modified manganese oxides will provides a new strategy for electrochemical sensing with high performance, low cost, and simple fabrication