Abstract: A method of making a porous material is provided. The method includes: preparing a mixture including a sugar, a polymer, and at least one soluble metal source, in water; heating the mixture to obtain a gelled material; thermally curing the gelled material to obtain a cured material; and annealing at least a part of the cured material to obtain a porous material that includes metal nanoparticles, where the metal nanoparticles include at least one metal from the at least one soluble metal source. The porous material can include: sheets of multilayer graphene layers; metal nanoparticles dispersed among the sheets and encapsulated by layers of graphene; and macropores, mesopores or micropores, or any combination thereof, throughout the porous material and on its surface. Methods of using the porous material to separate contaminants from water are also provided.