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Cu2O/Ag composite nanospheres (CNSs) with tunable Ag coverage and optical properties have been prepared based on a one-pot room temperature method by adding AgNO3 solution to fresh Cu2O nanosphere-produced mother solution in various ratios. Ag+ ions can be reduced by the primary Cu2O nanospheres in the acidic solution, and the obtained Ag nanoparticles can be deposited on the surfaces of the Cu2O nanospheres. The photocatalytic activity of Cu2O/Ag CNSs has been evaluated for photodegradation of methyl orange (MO) dye under visible-light irradiation, which demonstrates that Cu2O nanospheres with Ag loading exhibit significantly enhanced photocatalytic activity compared with pure Cu2O counterparts, and their photocatalytic properties depend on the coverage density of Ag nanoparticles. The enhanced photocatalytic activity can be attributed to the deposition of Ag acting as electron sinks to prevent the recombination of the photogenerated electrons and holes, and the plasmon resonances of the Ag nanoparticles generating more electron–hole pairs in the semiconductor.

International audienceFor the first time vapour sensors were made by assembling multi-wall carbon nanotube (CNT) decorated poly(methyl methacrylate) microbeads (PMMAµB) by spray layer by layer (sLbL). This combination of materials and technique resulted in an original hierarchical architecture with a segregated network of CNT bridging PMMAµB. The chemo-resistive behaviour of these conductive polymer nanocomposite (CPC) sensors was studied in terms of sensitivity and selectivity towards standard volatile organic compounds (VOC), as well as quantitativity and reproducibility of responses Ar to methanol, water, toluene and chloroform. Results show that 3D sLbL assembly allows boosting CNT network sensitivity by a factor 2 and selectivity for methanol vapour by a factor of 5. Additionally CNT-PMMAµB sensors gave responses proportional to vapour molecules content that could easily be fitted by the Langmuir-Henry-clustering model. Such sensors are thus expected to be good candidates for implementation in electronic noses