Catalyst mixtures
Catalysts that include at least one catalytically active element and one helper catalyst can be used to increase the rate or lower the overpotential of chemical reactions. The helper catalyst can simultaneously act as a director molecule, suppressing undesired reactions and thus increasing selectivity toward the desired reaction. These catalysts can be useful for a variety of chemical reactions including, in particular, the electrochemical conversion of CO 2 or formic acid. The catalysts can also suppress H 2 evolution, permitting electrochemical cell operation at potentials below RHE. Chemical processes and devices using the catalysts are also disclosed, including processes to produce CO, OH − , HCO − , H 2 CO, (HCO 2 ) − , H 2 CO 2 , CH 3 OH, CH 4 , C 2 H 4 , CH 3 CH 2 OH, CH 3 COO − , CH 3 COOH, C 2 H 6 , O 2 , H 2 , (COOH) 2 , or (COO − ) 2 , and a specific device, namely, a CO 2 sensor.
1. An electrochemical cell having a fluid phase, the fluid phase comprising a hydrogen evolution suppressor comprising a cation having at least one positive group selected from ammoniums and phosphoniums, and the cation further having at least one polar group covalently bonded to said cation and selected from the group consisting of —OR, —COR, —COOR, —NR 2 , —PR 2 , —SR and —X, where each R independently can be H or a linear, branched, or cyclic C1-C4 aliphatic group, —COOR is not a carboxylic acid, and —X is a halide.
2. The electrochemical cell of claim 1 , wherein the cation comprises a quaternary amine group and at least one halide or hydroxyl group, and the cation further contains no carboxylic acid or ionized carboxylic acid group.
3. The electrochemical cell of claim 1 , wherein said cation is choline, or a choline derivative of the form R 1 R 2 R 3 N + (CH 2 ) n Y, wherein n=1-4, R 1 , R 2 , and R 3 are independently selected from the group consisting of aliphatic C 1 -C 4 groups, —CH 2 OH, —CH 2 CH 2 OH, —CH 2 CH 2 CH 2 OH and —CH 2 CHOHCH 3 , and Y is selected from the group consisting of hydroxide and halides.
4. The electrochemical cell of claim 1 , wherein at least one of the reactants or the products of the reaction comprise at least one of the following: CO 2 , CO, CO 3 2− , HCO 3 − , HCO − , H 2 CO, (HCO 2 ) − , H 2 CO 2 , CH 3 OH, CH 4 , C 2 H 4 , CH 3 CH 2 OH, CH 3 COO − , CH 3 COOH, C 2 H 6 , (COOH) 2 , (COO − ) 2 .
5. The electrochemical cell of claim 1 , wherein the electrochemical cell is a fuel cell.
6. The electrochemical cell of claim 1 , wherein the electrochemical cell is a sensor.
7. The electrochemical cell of claim 1 , wherein the electrochemical cell is a cell for conversion of carbon dioxide.
8. The electrochemical cell of claim 1 , said cell further comprising at least one Catalytically Active Element, wherein the Catalytically Active Element comprises at least one of the following chemical elements: V, Cr, Mn, Fe, Co, Ni, Cu, Sn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Ir, Pt, Au, Hg, Al, Si, In, Tl, Pb, Bi, Sb, Te, U, Sm, Tb, La, Ce, and Nd.