Hollow Au nanoparticles (d ≈ 16 nm) with excellent thermal stability and high photothermal conversion efficiency, which have great potential for use in photo-thermal cancer therapy, were prepared through galvanic replacement reaction between Ag nano-templates and gold salt.

The recovery of metals from discarded mobile phones has been of interest due to its environmental and economic benefits. This work presents a simple and effective approach for leaching copper (Cu) from the printed circuit boards of discarded mobile phones by combining ultrasound and ozone approaches. The X-ray diffraction (XRD) technique and Fourier-transform infrared spectroscopy (FT-IR) were used to characterize the solid phases, and inductively coupled plasma optical emission spectrometry (ICP-OES) was utilized to determine the concentration of metals in the liquid phases. The effects of several influential parameters, including ultrasound, ozone dose, HCl concentration, liquid/solid ratio, temperature, and reaction time on the leaching efficiency were investigated. The results showed that the optimal conditions for Cu leaching included an ozone dose of 700 mg/h, HCl concentration of 3.0 M, liquid/solid ratio of 8, and temperature of 333 K. Under optimal conditions, about 99% of Cu was leached after 180 min. The shrinking core model was used to analyze the kinetics of the Cu leaching process, and the results showed that the surface chemical reaction governs this process. The activation energy of the leaching reaction, calculated using Two-Point form of the Arrhenius equation, was 10.852 kJ mol−1.

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In this work, Ag nanoparticles (NPs) were fabricated by thermal decomposition of silver nitrate in organic solvents in the presence of sodium oleate (SOA) and 1-octadecanol (OCD-ol). The effects of different solvents and concentrations of OCD-ol on the morphology and properties of the Ag nanomaterials were investigated in detail. The structural analysis of the Ag nanomaterials showed good crystallinity. The TEM images of the samples showed that with the change in the fabrication conditions, different sizes and shapes of Ag nanomaterials were formed. The surface plasmon resonance (SPR) properties of the  Ag NPs were influenced by their size and shape. The as-synthesized Ag NPs have potential applications in biomedical, catalysis, or electronics.