Search

Ruthenium oxide is a model pseudocapacitive materials exhibiting good electronic and protonic conduction and has been shown to achieve very high gravimetric capacitances. However, the capacitance of thermally prepared ruthenium oxide is generally low because of low protonic conductivity resulting from dehydration of the oxide upon annealing. High-temperature processing, however also produces the electrically conducting ruthenium oxide rutile phase, which is of great interest for electrochemical capacitors. Here, unusual electrochemical characteristics were obtained for thermally prepared ruthenium oxide when fabricated in the presence of alkyl-thiols at high temperature. The performance characteristics have been attributed to enhanced multifunctional properties of the material resulting from the novel processing. The processing method relies on a simple, solution-based strategy that utilizes a sacrificial organic template to sterically direct hierarchical architecture formation in electro-active ruthenium oxide. Thin films of the templated RuO2exhibit energy storage characteristics comparable to hydrous ruthenium oxide materials formed under dramatically different conditions. Extensive materials characterization has revealed that these property enhancements are associated with the retention of molecular-sized metal oxide clusters, high hydroxyl concentrations, and formation of hierarchical porosity in the ruthenium oxide thin films.

The integration of zinc oxide (ZnO) and cadmium sulfide (CdS) has shown promise in applications such as sensing and photovoltaics. We describe here a room temperature, aqueous synthetic strategy to selectively grow nanocrystalline CdS on ZnO. In particular, we describe an experimentally simple process that selectively grows a conformal nanocrystalline coating only 1 nanocrystal (10−20 nm) thick on planar and three-dimensional extended ZnO structures. We explore the synthesis, characterization, and mechanisms involved in the formation of this composite material, and we demonstrate a promising optical response from these composite structures that may prove valuable for future optoelectronic applications.