Sn Powder as Reducing Agents and SnO₂ Precursors for the Synthesis of SnO₂‑Reduced Graphene Oxide Hybrid Nanoparticles

A facile approach to prepare SnO₂/rGO (reduced graphene oxide) hybrid nanoparticles by a direct redox reaction between graphene oxide (GO) and tin powder was developed. Since no acid was used, it is an environmentally friendly green method. The SnO₂/rGO hybrid nanoparticles were characterized by ultraviolet–visible spectroscopy, Raman spectroscopy, thermogravimetric analysis, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The microstructure of the SnO₂/rGO was observed with scanning electron microscopy and transmission electron microscopy. The tin powder efficiently reduced GO to rGO, and the Sn was transformed to SnO₂ nanoparticles (∼45 nm) that were evenly distributed on the rGO sheets. The SnO₂/rGO hybrid nanoparticles were then coated on an interdigital electrode to fabricate a humidity sensor, which have an especially good linear impedance response from 11% to 85% relative humidity

Chemically Responsive Polymer Inverse-Opal Photonic Crystal Films Created by a Self-Assembly Method

The synthesis of poly-2-hydroxyethyl methacrylate inverse-opal hydrogel (IOHG_PHEMA) was realized by capillary-force-induced in situ polymerization in a polystyrene colloidal crystal template. The created IOHG_PHEMA films show brilliant blue-violet color when they are immersed in deionized water and reach swelling equilibrium. The stop band of the IOHG_PHEMA films can be tuned within the entire visible wavelength range by immersing them into different chemical solutions, such as aldehydes, ketones, amides, dimethyl sulfoxide, and alcohols. The extent of the reflective peak shift not only depends on the number of hydrogen band donors but also on the chain length and structure of the chemicals and their concentration. Since the IOHG_PHEMA films have different reflectance spectra and structural colors in response to different compounds of the same series, this provides a potential way to visually detect homologues and other compounds with similar structure and properties. This simple, yet effective, method also has the potential to be used generically to determine approximate concentration of the solution by direct visual observation of the color change

Self-Assembly Method To Fabricate Reduced Graphene Oxide Aerogels Loaded with Nickel Hydroxyl Nanoparticles and Their Excellent Properties in Absorbing and Supercapacitors

A facile method for preparing nickel hydroxyl nanoparticles loaded graphene aerogels has been established. The prepared aerogels were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. Their applications as absorbents or electrode materials for supercapacitors were investigated. They showed excellent performance on the absorption of different dyes. The absorption capacities ranged from 202 to 513 mg g^–1. They also displayed high absorption capacities toward oils and organic solvents. The aerogels demonstrated high capacitance and stability as electrode materials of supercapacitors. The specific capacitance reached 702 F g^–1 at current densities of 1 A g^–1