Effects of ultrasonic-assisted nickel pretreatment method on electroless copper plating over graphene.

In this paper, copper deposited graphene was fabricated through electroless plating. A novel and facile pretreatment method is introduced based on ultrasonic treatment with nickel nano-particles as the catalytic core. This method abandons the sensitization and activation process in the traditional pretreatment that reduces the time and economic cost dramatically. The static contact angle was determined by an Olympus BX51M optical microscope. The surface morphology and plating composition were characterized via scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), the infrared radiation (IR) transmittance spectra of the copper plated graphene were measured by Fourier transform infrared spectroscopy (FTIR), the layer structure was measured by Raman spectrum, the phase identification was identified by X-ray diffraction (XRD), the thermogravimetric analysis (TGA) (Q5000 TA instruments, USA) was carried out to detect the thermal characteristics. The electrical resistivity of copper-plated graphene was performed in an especially designed apparatus. The results show that the surface of graphene is coarsened, and the size is reduced after ultrasonic treatment, which can facilitate the nucleation and fine particle distribution of metal. The electroless plated efficiency of copper of the nickel pretreatment copper-plated graphene is 64.27 wt%, higher than that of generic copper-plated graphene at 58.62 wt%. The resistivity decreases rapidly from 1.69 × 10 Ω cm of the original Gr to 0.79 × 10 Ω cm of Cu/Ni@Gr due to the large number of fine copper particles scattered around the graphene.