An energy conversion device for conversion of chemical energy into electricity. The energy conversion device has a first and second electrode. A substrate is present that has a porous semiconductor or dielectric layer placed thereover. The porous semiconductor or dielectric layer can be a nano-engineered structure. A porous catalyst material is placed on at least a portion of the porous semiconductor or dielectric layer such that at least some of the porous catalyst material enters the nano-engineered structure of the porous semiconductor or dielectric layer, thereby forming an intertwining region.