NOVELTY - A catalyst (C1) comprising at least one catalytically active element and at least one helper catalyst, is new.    USE - As a catalyst used in carbon dioxide (CO2) sensor and fuel cell, and for making a chemical reaction product comprising at least one of the following: carbon monoxide (CO), hydroxy (OH-), aldehyde (HCO), formaldehyde (H2CO), HCO2-, formic acid (H2CO2), methanol (CH3OH), methane (CH4), ethylene (C2H4), ethanol (CH3CH2OH), acetyl acetate (CH3COO), acetic acid (CH3COOH), ethane (C2H6), oxygen (O2), hydrogen (H2), carboxylic acid ((COOH)2), (COO-)2, chlorine (Cl2), bromine (Br2), iodine (I2), sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium hypochlorite (NaClO), sodium chlorate (NaClO3), potassium chlorate (KClO3), and trifluoroacetic acid (CF3COOH) (claimed), and used in homogeneously or heterogeneously catalyzed reactions, chemical reactions in chemical plants, power plants, in pollution control equipment and devices, chemical reactions in fuel cells and in sensors.    ADVANTAGE - The catalyst mixture can overcome the limitations of low rates, high overpotentials and low electron conversion efficiencies (namely, selectivities) for catalytic reactions and high power for sensors. The catalyst mixture includes at least one catalytically active element, and at least one helper catalyst. When the catalytically active element and the helper catalyst are combined, the rate and/or selectivity of a chemical reaction can be enhanced over the rate seen in the absence of the helper catalyst. For e.g. the overpotential for electrochemical conversion of carbon dioxide can be reduced, and the current efficiency (namely, selectivity) for CO2 conversion can be increased. The catalysts that include catalytically active elements and helper catalysts enhance the rate of a wide variety of chemical reactions including: homogeneously catalyzed reactions, heterogeneously catalyzed reactions, chemical reactions in chemical plants, chemical reactions in power plants, chemical reactions in pollution control equipment and devices, chemical reactions in fuel cells, and chemical reactions in sensors.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for making a chemical reaction product, involving: combining a catalytically active element and helper catalyst in the presence of a reactant; allowing a reaction to proceed to produce a reaction product.