The unforeseen consequences of the environmental release of potentially harmful and toxic waste chemicals and solvents used during manufacturing processes are often ignored. Nanotechnology offers technological advances in numerous areas, from medicine to engineering, and can be more environmentally friendly. This research study describes two different eco-friendly (“green”) routes to chemically create multifunctional nanomaterialsNanomaterials with tunable sizes, morphologies (hollow and solid), and compositions. We employed a citrate approach to generate solid nanospheres with well-defined compositions (Au, Ag, Pt, Pd), sizes (20–50 nm), and properties. Silver nanospheres were used as sacrificial templates for the production of hollow bimetallicBimetallic hollow nanoparticles Ag-Au, Ag-Pt, and Ag-Pd nanostructures. Materials were characterized by electron microscopy, UV–visible spectroscopy, energy-dispersive X-ray analysis, dynamic light scattering, and zeta seizer to elucidate their properties. An added benefit of these technologies is that these processes are based on the use of a biodegradable reducing reagent, sodium citrate while maximizing the use of precursors.