Electrocatalytic materials for applications in batteries, fuel cells or chemical synthesis are often composites of (conducting) carbon and nanostructured metal particles. Metals used for this purpose are typically from the family of platinum metals or nickel and therefore share similar problems with poisoning (e.g. by CO) or deactiviation by agglomeration processes, thus often limiting the usefulness for instance of direct methanol fuel cells. In
order to overcome the inherent limitations of this class of materials, this work explores the electrocatalytic activity of semiconducting zinc chalcogenide nanoparticles, especially of those with a large band gap, in order to take advantage of their inherent chemical stability. From the literature, the photocatalytic activity of e.g. ZnS nanoparticles is well known, and thus the principal set of redox reactions that may be accelerated. Since ZnS nanoparticles are bad conductors, they have to be integrated into a carbon-based host before electrodes can be fabricated.
This work will present first data on the electrocatalytic activity of Zn(S,Se)/carbon nanocomposites in the presence of various organic materials in aqueous solution, especially alcohols. Suitable approaches to prepare the necessary semiconductor nanoparticles will be presented as well. Carbon hosts employed are varied from powder-based pastes to microporous materials, in order to acommodate the Zn(S,Se) nanoparticles in a conductive matrix. The experimental electrochemical stability window for the electrodes fabricated this way will be compared to the potential windows at which various potentially useful redox reactions are taking place. First results on ethanol oxidation on such electrodes will be presented, as derived from voltammetric analysis of the electrodes. |