Carbon Spheres with Controllable Silver Nanoparticle Doping

We report it facile method to dope submicrometer carbon spheres with Ag nanoparticles (NPs) to fabricate Ag-NP/C composites via microwaving Suspensions of nanoporous carbon spheres in aqueous Ag(NH3)(2)(+) solutions with poly(N-vinylpyrrolidone) as reducer. The composite particles are synthesized in high yield within a short reaction time, and the size, number density, and to some extent even the locations of NPs in/on the carbon spheres call be controlled by adjusting reaction parameters. The controllability is discussed based on the experimental results from transmission electron microscopy, X-ray photoelectron spectroscopy depth profiling, and X-ray diffraction. By controlling the Ag doping, the composite spheres exhibit not only a tunable plasmon resonance shift but also all excellent catalytic activity toward the reduction of 4-nitrophenol by sodium borohydride.