NOVELTY - Electrochemical cell (10) comprises: either a fluid phase, where the fluid phase includes a hydrogen evolution suppressor comprising a cation having at least one positive group including ammoniums or phosphoniums, and at least one polar group; or a catalytically active element and helper catalyst mixture.    USE - The electrochemical cell is useful as fuel cell, sensor or cell for conversion of carbon dioxide (claimed).    ADVANTAGE - The electrochemical cell: suppress undesired side reactions, i.e. evolution of hydrogen gas from the electrolysis of water; and utilizes the helper catalyst which (improves the rate or yield of a desired reaction, while simultaneously decreasing the rate or yield of an undesired reaction) reduces the cathode overpotential, and low electron conversion efficiencies of chemical reactions.    DETAILED DESCRIPTION - Electrochemical cell (10) comprises: either a fluid phase, where the fluid phase includes a hydrogen evolution suppressor comprising a cation having at least one positive group including ammoniums or phosphoniums, and at least one polar group including -OR, -COR, -COOR, -NR2, -PR2, -SR or X, where -COOR is not a carboxylic acid; or a catalytically active element and helper catalyst mixture.    R2 = linear, branched or cyclic 1-4C aliphatic group or H; and    X = halide.    INDEPENDENT CLAIMS are also included for:    (1) suppressing hydrogen gas evolution from water present in the electrochemical cell or operating the electrochemical cell at negative potentials with respect to reversible hydrogen electrode (RHE), comprising: providing the electrochemical cell having the fluid phase and a negative electrode; providing in the fluid phase the hydrogen evolution suppressor comprising the cation; and operating the electrochemical cell with the negative electrode at a potential that is negative with respect to the RHE; and    (2) a catalyst mixture, comprising the catalytically active element and the helper catalyst, where the helper catalyst also functions as a director molecule.    DESCRIPTION OF DRAWING(S) - The figure shows a view of the electrochemical cell.    Electrochemical cell (10)    Anode (50)    Cathode (51)    Membrane (52)    Electrolyte (53)