Synthesis of Ag–decorated vertical graphene nanosheets and their electrocatalytic efficiencies

Herein, we report the successful preparation of Ag–decorated vertical–oriented graphene sheets (Ag/VGs) via helicon wave plasma chemical vapor deposition (HWP–CVD) and radio frequency plasma magnetron sputtering (RF–PMS). VGs were synthesized in a mixture of argon and methane (Ar/CH4) by HWP–CVD, and then the silver nanoparticles on the prepared VGs were modified using the RF-PMS system under different sputtering times and RF power levels. The morphology and structure of the Ag nanoparticles were characterized by scanning electron microscopy (SEM), and the results revealed that Ag nanoparticles were evenly dispersed on the mesoporous wall of the VGs. X-ray diffraction (XRD) results showed that the diameter of the Ag particles increased with the increase of silver loading, and the average size was between 10.49 nm and 25.9 nm, which were consistent with transmission electron microscopy (TEM) results. Ag/VGs were investigated as effective electrocatalysts for use in an alkaline aqueous system. Due to the uniquely ordered and interconnected wall structure of VGs, the area of active sites increased with the Ag loading, which made the Ag/VGs have high oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) performance. The double–layer capacitance (Cdl) of the Ag/VGs under different silver loadings were studied, and the results showed that highest silver content is the best (1.04 mF/cm2). The results showed that, Ag/VGs expected to be a credible electrocatalytic material.

Green Synthesis of Surfactant Capped CTAB@Ag Nanoparticles and Study of Its Catalytic Activity

In the present study, ginger extract, which is widely available as a medicinal herb, is used to develop a facile method for green synthesis of bare Ag and surfactant capped CTAB@Ag nanoparticles via Hydrothermal route. The as-prepared Ag nanoparticles were characterized by UV-Vis spectroscopy, photoluminescence (PL), X-ray Diffraction (XRD), Infrared spectroscopy (IR), and Scanning electron microscopy (SEM). The catalytic properties of as prepared bare and surfactant capped CTAB@Ag nanoparticles were also investigated in reductive degradation of Methyl Orange (MO) dye and 4-Nitrophenol (4-NP). Surfactant-capped CTAB@Ag nanoparticles exhibit superior catalytic properties in the degradation of MO and conversion of 4-nitro phenol to 4-amino phenol when compared to bare silver nanoparticles.

Silver nanoparticles embedded 2D g-C3N4 nanosheets toward excellent photocatalytic hydrogen evolution under visible light

Photocatalytic water splitting is considered to be a feasible method to replace traditional energy. However, most of the catalysts have unsatisfactory performance. In this work, we used a hydrothermal process to grow Ag nanoparticles in situ on g-C3N4 nanosheets, and then a high performance catalyst (Ag- g-C3N4) under visible light was obtained. The Ag nanoparticles obtained by this process are amorphous and exhibit excellent catalytic activity. At the same time, the local plasmon resonance effect of Ag can effectively enhance the absorption intensity of visible light by the catalyst. The hydrogen production rate promote to 1035 μmol g-1h-1 after loaded 0.6 wt% of Ag under the visible light, which was 313 times higher than that of pure g-C3N4 (3.3μmol g-1h-1). This hydrogen production rate is higher than most previously reported catalysts which loaded with Ag or Pt. The excellent activity of Ag- g-C3N4 is benefited from the Ag nanoparticles and special interaction in each other. Through various analysis and characterization methods, it is shown that the synergy between Ag and g-C3N4 can effectively promote the separation of carriers and the transfer of electrons. Our work proves that Ag- g-C3N4 is a promising catalyst to make full use of solar energy.