We are presenting our recent research results about the Ni-NiO nanoparticles on poly-(diallyldimethylammonium chloride)-modified graphene sheet (Ni-NiO/PDDA-G) nanocomposites prepared by the hydrothermal method at 90°C for 24 h. The Ni-NiO nanoparticles on PDDA-modified graphene sheets are measured by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) pattern for exploring the structural evidence to apply in the electrochemical catalysts. The size of Ni-NiO nanoparticles is around 5 nm based on TEM observations. The X-ray diffraction (XRD) results show the Ni in the (012), (110), (110), (200), and (220) crystalline orientations, respectively. Moreover, the crystalline peaks of NiO are found in (111) and (220). The thermal gravimetric analysis (TGA) result represents the loading content of the Ni metal which is about 34.82 wt%. The electron spectroscopy for chemical analysis/X-ray photoelectron spectroscopy (ESCA/XPS) reveals the Ni⁰ to Ni^II ratio in metal phase. The electrochemical studies with Ni-NiO/PDDA-G in 0.5 M aqueous H₂SO₄ were studied for oxygen reduction reaction (ORR).

Stainless steel 304L (SS304L) has been selected as the material for canisters for spent fuel storage from three nuclear power plants in Taiwan. A crucial issue is extending the spent fuel storage safety standards of the canisters. The anti-saline corrosion abilities of three thermal spray coatings (i.e., Al, ZnAl, and 625 Inconel alloys) on the SS304L were evaluated by immersion in 3.5 wt % aqueous NaCl and with 0.025 g/cm² NaCl deposition at 80 °C and 80% relative humidity (RH) for 1000 h. The pristine thermal spray coatings were examined using the pull-off adhesion test to understand the adhesion strength, and Vickers hardness was measured for the mechanical properties of the three coatings. Confocal laser scanning microscopy (CLSM) was used to identify the porosities of the coatings. Furthermore, the surfaces of the specimens before and after corrosion were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). The composition and distribution of the oxide layers formed on the coating surfaces during corrosion were evaluated. Electrochemical measurement was also performed with the polarization method to quantify the corrosion property of the three thermal spray coatings. The results showed that the corrosion rate of Al coating was lowest from the Tafel analysis after the 1000 h corrosion test in 3.5% aqueous NaCl. In contrast, the corrosion rate of Inconel 625 was lowest after 1000 h of the NaCl deposition corrosion test in a controlled environment. Therefore, the ZnAl thermal spray coating is a potential protection layer, keeping in mind economic considerations, of SS304L for anti-corrosion in saline environments.

The microwave-assisted nanocomposite synthesis of metal nanoparticles on graphene or graphite oxide was introduced in this research. With microwave assistance, the Pt nanoparticles on graphene/graphite oxide were successfully produced in the ionic liquid of 2-hydroxyethanaminium formate [HOCH₂CH₂NH₃][HCO₂]. On graphene/graphite oxide, the sizes of Pt nanoparticles were about 5 to 30 nm from transmitted electron microscopy (TEM) results. The crystalline Pt structures were examined by X-ray diffraction (XRD). Since hydrogenation of styrene is one of the important well-known chemical reactions, herein, we demonstrated then the catalytic hydrogenation capability of the Pt nanoparticles on graphene/graphite oxide for the nanocomposite to compare with that of the commercial catalysts (Pt/C and Pd/C, 10 wt.% metal catalysts on activated carbon from Strem chemicals, Inc.). The conversions with the Pt nanoparticles on graphene are >99% from styrene to ethyl benzene at 100°C and under 140 psi H₂ atmosphere. However, ethyl cyclohexane could be found as a side product at 100°C and under 1,520 psi H₂ atmosphere utilizing the same nanocomposite catalyst.

Nanocomposite materials of the Au nanoparticles (Au/PDDA-G) and the bimetallic PtAu nanoparticles on poly-(diallyldimethylammonium chloride) (PDDA)-modifie

The results of studies on the corrosion protectiveness and thermal conductivity of reduced graphene oxide–BaSO₄ epoxy composites are reported here. A commercial epoxy resin and reduced graphene oxide (rGO) were blended with a hardening reagent and then mixed with prepared BaSO₄–epoxy resin (B–epoxy). The reduced graphene oxide–BaSO₄–epoxy composite (rGO–B–epoxy) paste was used to coat the surfaces of Al 7205 alloy and the corrosion and thermal properties were investigated. A corrosion test in a 3.5 wt% synthetic sea water solution showed that the composite coating containing BaSO₄ had the best corrosion resistance. Moreover, the rGO–B–epoxy composite showed better protection against corrosion than the epoxy alone. The rGO–B–epoxy composite with 5 wt% BaSO₄ had an in-plane coefficient of thermal conductivity of approximately 165.0 W/m K, and the in-plane thermal diffusivity was 71.38 mm²/s. In standard thermal conductivity tests, all three samples had values below 40 W/m K. The rGO–B–epoxy composites showed good surface corrosion protection and in-plane thermal conductivity.

We have successfully produced bimetallic PtNi alloy nanoparticles on poly(diallyldimethylammonium chloride) (PDDA)-modified graphene nanosheets (PtNi/PDDA-G) by the “one-pot” hydrothermal method. The size of PtNi alloy nanoparticles is approximately 2–5 nm. The PDDA-modified graphene nanosheets (PDDA-G) provides an anchored site for metal precursors; hence, the PtNi nanoparticles could be easily bond on the PDDA-G substrate. PtNi alloy nanoparticles (2–5 nm) display a homogenous alloy phase embedded on the PDDA-G substrate, evaluated by Raman, X-ray diffractometer (XRD), thermal gravity analysis (TGA), electron surface chemical analysis (ESCA), and electron energy loss spectroscopy (EELS). The Pt/Ni ratio of PtNi alloy nanoparticles is ~1.7, examined by the energy dispersive spectroscopy (EDS) spectra of transmitting electron microscopy (EDS/TEM spectra) and mapping technique. The methanol electro-oxidation of PtNi/PDDA-G was evaluated by cyclic voltammetry (CV) in 0.5 M of H₂SO₄ and 0.5 M of CH₃OH. Compared to Pt on carbon nanoparticles (Pt/C) and Pt on Graphene (Pt/G), the PtNi/PDDA-G exhibits the optimal electrochemical surface area (ECSA), methanol oxidation reaction (MOR) activity, and durability by chrono amperometry (CA) test, which can be a candidate for MOR in the electro-catalysis of direct methanol fuel cells (DMFC).