Hierarchically driven nanostructure electrocatalysts for direct sensing of biomolecules

Applying nanoscale device fabrications toward biomolecules, ultra sensitive, selective, robust, and reliable chemical or biological microsensors have been one of the most fascinating research directions in our life science. It is still challenging to make miniaturized sensors having the sensitive delectability to biologically relevant species due to limitations in terms of catalytic efficiency and sustainability. We introduce hierarchically driven iridium dioxide nanowires (IrO$_{2}$ NWs) directly on a platinum (Pt) microwire, which allows a simple fabrication of the amperometric sensor and shows a favorable electronic property desired for sensing of H$_{2}$O$_{2}$ and NADH without aid of enzymes. We have prepared highly crystalline IrO$_{2}$ needlelike-NWs by an atmospheric pressure chemical vapor deposition of IrO$_{2}$ powder without catalyst on a Pt wire surface, IrO$_{2}$ NWs-Pt, which was tested as an amperometric microsensor. The structures and morphologies of the IrO$_{2}$ NWs were characterized using FE-SEM, HRTEM and Raman spectroscopy. This rational engineering of a nanoscale architecture based on the direct formation of the 1-D nanostructures on an electrode can offer a useful platform for high performance electrochemical biosensors efficiently, sensitive detection of biologically important molecules.