Natural Alginate as a Graphene Precursor and Template in the Synthesis of Nanoparticulate Ceria/Graphene Water Oxidation Photocatalysts

Using alginate, a natural polysaccharide from algae, simultaneously as a graphene precursor and a templating agent for ceria nanoparticles, we have prepared a series of materials consisting of highly crystalline ceria nanoparticles embedded on a few-layer graphene matrix. XPS analysis indicates that the predominant oxidation state of Ce in the as-synthesized CeOx/graphene material is +III (over 80 atom %). Varying the weight percentage of ceria/alginate and the pyrolysis temperature enabled the preparation of a ceria/graphene photocatalyst that exhibits about 3 times higher photocatalytic activity for water oxidation to oxygen than commercial ceria. Our results on the ceria/graphene composite as a photocatalyst for water oxidation expand and complement the well-known effect of graphene to increase the photocatalytic efficiency of titania/graphene composites.