This work reports a green and facile approach to the synthesis of graphene nanosheets through the zinc reduction of a graphene oxide precursor in alkaline media. Compared to the chemical reduction of GO by using hydrazine or its derivations, the present route is operationally easy and environmentally friendly. Moreover, the reduction degree of GO in the present condition is much higher than that in either Zn or alkaline solutions alone, indicating a cooperative mechanism, and the as-prepared graphene exhibits a good stability in solution. This simple method shows promising applications in the bulk-quantity production of graphene and graphene-based materials.

Hexagonal close-packed Ni (h-Ni) nanocrystals and face-centered cubic Ni (c-Ni) nanoflowers with uniform size and high dispersion have been successfully assembled on graphene nanosheets (GN) via a facile one-step solution-phase strategy under different reaction conditions, where the reduction process of graphite oxide (GO) sheets into GN was accompanied by the generation of Ni nanocrystals. The reduction of GO by this method is effective, which was confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy and is comparable to conventional methods. The phase and morphology of nickel can be easily tuned by varying the reaction temperature and solvent. It was shown that the as-formed h-Ni nanocrystals with a diameter as small as 3 nm are grown densely and uniformly on the graphene sheets, and as a result the aggregation of the h-Ni nanocrystals was effectively prevented. In addition, c-Ni nanospheres assembled by c-Ni nanocrystals with a size of 15 nm were also uniformly deposited on the graphene sheets. The investigation of the microwave absorbability reveals that the three Ni/GN nanocomposites exhibit excellent microwave absorbability, which is stronger than the corresponding Ni nanostructures.

Anatase/rutile mixed-phase TiO₂ nanoparticles were synthesized through a simple sol-gel route with further calcination using inexpensive titanium tetrachloride as a titanium source, which effectively reduces the production cost. The structural and optical properties of the prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis adsorption. The specific surface area was also analyzed by Brunauer–Emmett–Teller (BET) method. The anatase/rutile mixed-phase TiO₂ nanocomposites containing of rod-like, cuboid, and some irregularly shaped anatase nanoparticles (exposed {101} facets) with sizes ranging from tens to more than 100 nanometers, and rod-like rutile nanoparticles (exposed {110} facets) with sizes ranging from tens to more than 100 nanometers. The photocatalytic activities of the obtained anatase/rutile mixed-phase TiO₂ nanoparticles were investigated and compared by evaluating the degradation of hazardous dye methylene blue (MB) under ultraviolet light illumination. Compared to the commercial Degussa P25-TiO₂, the mixed-phase TiO₂ nanocomposites show better photocatalytic activity, which can be attributed to the optimal anatase to rutile ratio and the specific exposed crystal surface on the surface. The anatase/rutile TiO₂ nanocomposites obtained at pH 1.0 (pH1.0-TiO₂) show the best photocatalytic activity, which can be attributed to the optimal heterojunction structure, the smaller average particle size, and the presence of a specific exposed crystal surface. The enhanced photocatalytic activity makes the prepared anatase/rutile TiO₂ photocatalysts a potential candidate in the removal of the organic dyes from colored wastewater.