In one aspect, an oxygenated hierarchically porous carbon (an “O-HPC”) is provided, the O-HPC comprising: a hierarchically porous carbon (an “HPC”), the HPC comprising a surface, the surface comprising: (A) first order pores having an average diameter of between about 1 μm and about 10 μm; and (B) walls separating the first order pores, the walls comprising: (1) second order pores having a peak diameter between about 7 nm and about 130 nm; and (2) third order pores having an average diameter of less than about 4 nm, wherein at least a portion of the HPC surface has been subjected to O2 plasma to oxygenate and induce a negative charge to the surface. In one aspect, the O-HPC further comprises metal nanoparticles dispersed within the first, second, and third order pores. Methods for making and using the metal nanoparticle-impregnated O-HPCs are also provided.