In a method for manufacturing a nanoparticle, a precursor (e.g., transition metal complex) mixed with polyethylene glycol (PEG) is thermally decomposed. A nanoparticle is formed from the thermal decomposition. PEG is cost effective and less toxic than chemicals that are conventionally used for nanoparticle production, so that costs for manufacturing the nanoparticle may be decreased. Further, PEG may be reused to produce more nanoparticles.