The Cu-based electrical contact composites containing reinforcement (Cr2Nb particles) and solid lubricants (NbSe2 particles) were fabricated by a powder metallurgy method, and their mechanical and electrical properties were investigated. The wear tests of Cu-based composites were performed on a ball on disc under dry sliding conditions in a laboratory atmosphere and the worn surface of the Cu-based composites was observed by using scanning electron microscopy. Experimental results indicated that Cu-based composite materials containing Cr2Nb and NbSe2 nanofibers possessed lower electrical resistivity and better prominent tribological properties than Cu/NbSe2 and Cu/Cr2Nb composites, and that the friction coefficient and wear rate of the composites gradually decreased with the increase of NbSe2 nanofiber content. The lubricating effect of the Cu-based composites containing 25 wt% NbSe2 nanofibers and 10 wt% Cr2Nb particles was outstanding with a friction coefficient close to 0.15. The tribological properties of Cu-based composites were affected by the size and morphology of NbSe2 particles, and Cu-based composites with NbSe2 nanofibers have been proven to be more effective to reduce friction and wear compared to Cu-based composites containing commercially available NbSe2 micro-particles under dry sliding conditions. Furthermore, the addition of Cr2Nb could improve the hardness and oxidation resistance of composites, and consequently enhance wear resistance and conductivity of Cu-based composites.

●The uniform 3D flower-like MoS2 microspheres were synthesized via a simple hydrothermal approach.●The obtained 3D flower-like MoS2 microspheres were dispersed well and the diameter of the microspheres was about 4 μm.●A possible formation mechanism of the MoS2 microspheres was proposed.Three-dimensional (3D) flower-like MoS2 microspheres with diameter of about 4 μm were successfully synthesized by a facile hydrothermal solution reaction method, using hexaammonium heptamolybdate tetrahydrate ((NH4)6Mo7O24) and thiourea as the precursors. As-prepared MoS2 samples were characterized by XRD, EDS, SEM, and TEM. SEM results showed that the obtained 3D flower-like MoS2 microspheres are comprised of very thin nanosheets with the thickness about 20 nm. The influence of reaction time on the formation of MoS2 microspheres was investigated. A possible growth mechanism is proposed to explain the formation of MoS2 microspheres on the basis of observations of a time-dependent morphology evolution process.

MoS2 flower-like microspheres with a mean diameter of about 1 μm, assembled by nanosheets, were successfully synthesized through a Pluronic F-127 (Ethylene Oxide/Propylene Oxide Block Copolymer) assisted hydrothermal method. The as-prepared products were characterized using powder X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM); UMT-2 multispecimen tribotester was used to assess their lubricating effect when used as additives in liquid paraffin dispersions. And the topography of worn scars was measured using a common scanning electron microscopy. Moreover, the relationship between the tribological properties and morphology of MoS2 were discussed. Tribological performance evidenced that the obtained flower-like MoS2 microspheres possessed superior anti-wear and friction-reducing properties as a lubrication additive compared with pure base oil and base oil containing commercial MoS2 plates, which will penetrate more easily into the interface with base oil, and form continuous film in concave of rubbing surface, enhancing the tribological properties.

A facile and effective hydrothermal method for the fabrication of the Ag3PO4-graphene (Ag3PO4-GR) visible light photocatalyst has been developed to improve the photocatalytic performance and stability of Ag3PO4, and also to reduce the high cost of Ag3PO4 for practical uses. The size and morphology of Ag3PO4 particles could be tailored by the electrostatically driven assembly of Ag+ on graphene oxide (GO) sheets and by the controlled growth of Ag3PO4 particles on the GO surface. The generation of Ag3PO4 and the transformation of GO to GR can be achieved simultaneously in the hydrothermal process. The improved photocatalytic activity of Ag3PO4-GR composites under visible light irradiation is attributed to high-surface-area GR sheets, enhanced absorption of organic dyes, and more efficient separation of photogenerated electron–hole pairs. The transfer of photogenerated electrons from the surface of Ag3PO4 to GR sheets also reduces the possibility of decomposing Ag+ to metallic Ag, suggesting an improved stability of recyclable Ag3PO4-GR composite photocatalyst. Moreover, with the advances in the large-scale production of high-quality GO, the use of GO as the starting material can also reduce the cost for the synthesis of Ag3PO4-based photocatalysts without weakening their photocatalytic activities.Keywords: Ag3PO4; composites; graphene; hydrothermal; visible light photocatalytic

Graphene oxide (GO)-enwrapped Ag3PO4 composites were successfully fabricated by the electrostatically-driven assembly of positively charged silver ions on the negatively charged GO sheets, followed by the controlled growth of sphere-like Ag3PO4 particles on GO sheets via an in-situ ion-exchange method. Moreover, GO–Ag3PO4 composites were fully characterized and the visible light photocatalytic performance of the GO–Ag3PO4 sample was investigated. The results indicated that the presence of GO sheets could effectively tailor the size of Ag3PO4 particles, GO–Ag3PO4 composites exhibited excellent visible-light absorption, and the photocatalytic degradation efficiency of Rhodamine B (RhB) over GO–Ag3PO4 composites is apparently higher than with pure Ag3PO4 mainly due to the photo-induced holes and the generation of irradiated active superoxide radicals.Highlights► Facile synthesis of graphene oxide (GO)-enwrapped Ag3PO4 composites. ► Use of a low amount of graphene oxide provides more active sites for the electrostatically-driven assembly. ► Presence of graphene oxide tailors the size and morphology of Ag3PO4 particles. ► Graphene oxide (GO)-enwrapped Ag3PO4 composites exhibited highly efficient visible light photocatalytic degradation rate of RhB. ► Photo-induced holes and superoxide radicals are suggested to be responsible for their excellent visible-light-driven photocatalytic performance.