TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The redox catalyst comprises one or more metals selected from platinum (Pt), palladium (Pd), bismuth (Bi), tellurium (Te), tungsten (W), iron (Fe), cobalt (Co), manganese (Mn), molybdenum (Mo), vanadium (V), ruthenium (Ru), copper (Cu) and silver (Ag). The redox catalyst is a nitrogen oxide (NOx). The redox catalyst comprises an organometallic complex, where the organometallic complex is a metal macrocycle or metal chelate complex. The metal complex is M(salophen). The electrolyte solution further comprises a pH buffer that is capable of accepting protons from and giving protons to the redox mediator; and oxygen.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: In the system, the reduced form of the redox mediator is selected from an unsubstituted dihydroxybenzene, a substituted dihydroxybenzene, and a substituted hydroxylamine. The substituted or unsubstituted dihydroxybenzene is 1,2-dihydroxybenzene (catechol) or 1,4-dihydroxybenzene (hydroquinone). One or more hydrogen atoms in the substituted dihydroxybenzene is substituted with a substituent group that is independently selected from an alkyl with less than ten carbons, an aryl, a fused aryl, napthoquinone and derivatives, anthraquinone and derivatives, a heterocycle, an alkenyl, an alkynyl, a cycloalkyl, an amine, a protonated amine, a quaternary amine, sulfate, a sulfonate, sulfonic acid, phosphate, a phosphonate, a phosphinate, a ketone, an aldehyde, a hydrazone, an oxime, a nitrone, an ether, an ester, a halide, a nitrile, a carboxylate, an amide, a thioether, a fluoroalkyl, a perfluoroalkyl, a pentafluorosulfanyl, a sulfonamide, a sulfonic ester, an imide, a carbonate, a carbamate, an urea, a sulfonylurea, an azide, a sulfone, a sulfoxide, an amine oxide, phosphine oxide, a quaternary phosphonium, a quaternary borate, a siloxane, and a nitro. One or more hydrogen atoms in the substituted hydroxylamine is substituted with a substituent group that is independently selected from an alkyl with less than ten carbons, an aryl, a heterocycle, a cycloalkyl, and a bicycloalkyl. One or more of the substituent groups further comprises an alkyl with less than ten carbons, an aryl, a heterocycle, an alkenyl, an alkynyl, a cycloalkyl, an amine, a protonated amine, a quaternary amine, sulfate, a sulfonate, sulfonic acid, phosphate, a phosphonate, a phosphinate, a ketone, an aldehyde, an oxime, a hydrazone, a nitrone, an ether, an ester, a halide, a nitrile, carboxylate, an amide, a thioether, a fluoroalkyl, a perfluoroalkyl, a pentafluorosulfanyl, a sulfonamide, a sulfonic ester, an imide, carbonate, a carbamate, urea, a sulfonylurea, an azide, a sulfone, a sulfoxide, an amine oxide, a phosphine oxide, a quaternary phosphonium, a quaternary borate, a siloxane, a nitro, and combinations of two or more on the same or on different positions on the substituent. The reduced form of the redox mediator is 1,4-dihydroxybenzene (hydroquinone). The redox catalyst is a cobalt organometallic complex. The form of the redox mediator is (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO), 4-acetamidoTEMPO, or 9-azabicyclo(3.3.1)nonane N-oxyl (ABNO).