No abstract

A straightforward one-step chemical method to in situ synthesis of Ag nanoparticles (Ag NPs) on single-layer graphene oxide (GO) and reduced graphene oxide (r-GO) surfaces is proposed. After simply heating the single-layer GO or r-GO adsorbed on 3-aminopropyltriethoxysilane (APTES)-modified Si/SiOx substrates in a silver nitrate aqueous solution at 75 °C, Ag NPs are synthesized and grow on the GO or r-GO surface. The obtained Ag NPs are investigated by atomic force microscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. Our method is unique and important since no reducing agent is required in the reaction. Au NPs on a GO surface are obtained by simply immersing the obtained Ag NPs on the GO surface in HAuCl4 solution.

Monocrystalline ZnO nanorods (NRs) with high donor concentration are electrochemically deposited on highly conductive reduced graphene oxide (rGO) films on quartz. The film thickness, optical transmittance, sheet resistance, and roughness of rGO films are systematically studied. The obtained ZnO NRs on rGO films are characterized by X-ray diffraction, transmission electron microscopy, photoluminescence, and Raman spectra. As a proof-of-concept application, the obtained ZnO NRs on rGO are used to fabricate inorganic-organic hybrid solar cells with layered structure of quartz/rGO/ZnO NR/poly(3-hexylthiophene)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (P3HT/PEDOT:PSS)/Au. The observed power conversion efficiency (PCE, eta), approximately 0.31%, is higher than that reported in previous solar cells by using graphene films as electrodes. These results clearly demonstrate that rGO films with a higher conductivity have a smaller work function and show a better performance in the fabricated solar cells.

A direct electrochemical method to reduce single-layer graphene oxide (GO) adsorbed on the 3-aminopropyltriethoxysilane (APTES)-modified conductive electrodes is proposed. The reduced GO adsorbed on glassy carbon electrode was modified with glucose oxidase (GOx) by covalent bonding via a polymer generated by electrografting N-succinimidyl acrylate (NSA). The direct electron transfer between the electrode and GOx molecules was realized. The bioactivity of GOx maintains very well on the electrode. The thus-prepared GOx-modified electrode was successfully used to detect glucose.

Nanoparticles can be combined with nucleic acids to programme the formation of three-dimensional colloidal crystals where the particles' size, shape, composition and position can be independently controlled. However, the diversity of the types of material that can be used is limited by the lack of a general method for preparing the basic DNA-functionalized building blocks needed to bond nanoparticles of different chemical compositions into lattices in a controllable manner. Here we show that by coating nanoparticles protected with aliphatic ligands with an azide-bearing amphiphilic polymer, followed by the coupling of DNA to the polymer using strain-promoted azide-alkyne cycloaddition (also known as copper-free azide-alkyne click chemistry), nanoparticles bearing a high-density shell of nucleic acids can be created regardless of nanoparticle composition. This method provides a route to a virtually endless class of programmable atom equivalents for DNA-based colloidal crystallization.