Controllable synthesis of hollow hierarchical palladium nanostructures with enhanced activity for proton/hydrogen sensing

The hollow Pd nanostructures were fabricated using Co nanoparticles as sacrificial templates to obtain two geometries, namely, raspberry-like and nanotube-like hierarchical architectures. These hollow nanostructures are extensively characterized by TEM, XRD, HRTEM, SEM, and energy dispersive X-ray analysis. Particularly, hollow raspberry-like Pd nanostructure exhibit enhanced activity for proton/hydrogen sensing compared to solid Pd nanoparticles (diameter ca. 3 nm), Pd microparticles (diameter 1-1.5 mu m), and a planar 3 mm diameter Pd electrode. It is the contribution of the hollow nanostructure and the presence of the smaller nanoparticles on its shell that allow the weakly capped structure to produce this stronger and more specific stable response.