Photochemical loading of metal nanoparticles on reduced graphene oxide sheets using phosphotungstate

Well-dispersed reduced graphene oxide (r-GO) sheets loaded with metal nanoparticles were produced in dimethylformamide (DMF). The r-GO suspension was prepared through the photocatalytic reduction of graphene oxide (GO) using a phosphotungstate as a homogeneous photocatalyst under UV irradiation. Immediately after UV lamp was turned off, the injection of precursors of Ag, Au, and Pd caused the rapid nucleation because photoreduced phosphotungstates as well as electrons stored in r-GO directly reduced metal ions. Furthermore, the r-GO sheets not only provided the nucleation sites but also prohibited the metal nanoparticles from agglomeration. As a result, relatively uniform-sized metal nanoparticles were formed on the r-GO sheets. With phosphotungstates and UV light irradiation, both GO and metal ions can be reduced to form the hybrids of Ag, Au, and Pd/r-GO as a suspension in DMF or an isolated paper sheet without using any toxic reagents.