Metal Nanoparticle Carbon Gel Composites in Environmental Water Sensing Applications

The synthesis of organic-inorganic nanocomposites that can interact with different environmental pollutants and can be mass-produced are very promising materials for the fabrication of chemical sensor devices. Among them, metal (or metal oxide) nanoparticles doped conductive porous carbon composites can be readily applied to the production of electrochemical sensors and show enhanced sensitivity for the measurement of water pollutants, thanks to the abundant accessible and functional sites provided by the interconnected porosity and the metallic nanoparticles, respectively. In this personal account, an overview of several synthesis routes of porous carbon composites containing metallic nanoparticles is given, paying special attention to those based on sol-gel techniques. These are very powerful to synthesize hybrid porous materials that can be easily processed into powders and thin films, so that they can be implemented in electrode fabrication processes based on screen-printing and lithography techniques, respectively. We emphasize the sol-gel routes developed in our group for the synthesis of bismuth or gold nanoparticle doped porous carbon composites applied to fabricate electrochemical sensors that can be scaled down to produce miniaturized on-chip sensing devices for the sensitive detection of heavy metal pollutants in water. The trend towards the miniaturization of electrochemical sensors to be readily employed as analytical tools in environmental monitoring follow the market requirements of rapid and accurate on-site analysis, small sample consumption and waste production, as well as potential for continuous or semi-continuous in-situ determination of a wide variety of target analytes.