Electrochemical Method for Producing and Storing Hydrogen by the Redox of Zinc and Water

Abstract

Disclosed herein is an electrochemical method for producing and storing hydrogen, which is a closed system consisting of a gas-generating electrode, an electrolyte and a zinc electrode, the gas-generating electrode and zinc electrode are connected respectively to the external circuits; characterized in that switching on the external circuit of the gas-generating electrode and zinc electrode the hydrogen is to be released, the reduction reaction of water occurs on the gas-generating electrode producing hydrogen; zinc is oxidized on the zinc electrode generating the oxidation products of zinc; when the hydrogen is to be stored, supplementary water is supplied to the closed system, the negative pole of power source is connected to the external circuit of the zinc electrode, and the positive pole of power source is connected to the external circuit of the gas-generating electrode, switching on the direct current, the reduction reaction of zinc occurs on the zinc electrode, the oxidation products of zinc are reduced into zinc, renew the zinc electrode, the oxidation reaction of water occurs on the gas-generating electrode, the oxygen is generated and discharged. A simple and convenient process and widely applied are property of the present invention. It suits to provide hydrogen for hydrogen fuel cells. While providing the hydrogen, it can also generate electricity as secondary product, which generates the electricity together with a fuel cell.

1 . An electrochemical method for producing and storing hydrogen in a closed system consisting of a gas-generating electrode, an electrolyte and a zinc electrode, the gas-generating electrode and zinc electrode are connected respectively to the external circuit; wherein switching on the external circuit of the gas-generating electrode and zinc electrode the hydrogen is to be released, the reduction reaction of water occurs on the gas-generating electrode producing hydrogen, zinc is oxidized on the zinc electrode generating the oxidation products of zinc; when the hydrogen is to be stored, supplementary water is supplied to the closed system, the negative pole of power source is connected to the external circuit of the zinc electrode, and the positive pole of power source is connected to the external circuit of the gas-generating electrode, switching on the direct current, the oxidation products of zinc are reduced into zinc on the zinc electrode, renew the zinc electrode, the oxidation reaction of water occurs on the gas-generating electrode, the oxygen is generated and discharged. 
     
     
         2 . The electrochemical method for producing and storing hydrogen described according to  claim 1 , wherein the gas-generating electrode consists of the hydrogen-generating electrode and oxygen-generating electrode; or consists of the hydrogen-generating electrode that is concurrently as the oxygen-generating electrode. 
     
     
         3 . The electrochemical method for producing and storing hydrogen described according to  claim 1 , wherein the zinc electrode is made of zinc active substance, adhesive, additives, current-collecting device by using physical methods such as compacting, applying paste, agglomerating, boxing or piping, foaming, electrodeposition technology, and is composed of zinc active substance selected from the group consisting of zinc alloy powder, zinc oxide, zinc hydroxide, zinc compound such as zincate or mixtures their of; the adhesive selected from the group consisting of carboxymethyl cellulose, polytetrafluoroethylene emulsion, polyvinyl alcohol, hydroxypropyl emthylcellulose, polyethylene oxide, polyacrylic acid or polyvinylidene fluoride, hexafluoropropylene, or mixture thereof; the additives selected from the group consisting of zinc oxides, calcium oxide, magnesium oxide, cadmium oxide, alumina, indium compounds, bismuth compounds, lead compounds, calcium hydroxide, graphite powder, acetylene black, carbon powder, electric carbon black, active carbon powder, short-cut fiber, or carbon fibers, or mixtures thereof; current-collecting device being made of any one selected from the group consisting of foamed metal, metal mesh, metal tape (metal can be pure metal or alloy) by using the physical and chemical methods such as electroplating, composite plating to treat the surface of the metal; and preferably the punched brass strip, brass screen of the foamed brass, lead plating or tin plating. 
     
     
         4 . The electrochemical method for producing and storing hydrogen described according to  claim 1 , wherein the zinc electrode is a flaky or porous powder structure, and preferably the porous powder structure. 
     
     
         5 . The electrochemical method for producing and storing hydrogen described according to  claim 1 , wherein the electrolyte is an aqueous solution electrolyte, and is absorbed by the battery diaphragm, the pH of the aqueous solution is more than 4, and concentration of the aqueous solution is in range of 0.05 Mol/L-15 Mol/L; the hydroxide aqueous solution selected from the alkali metal or alkaline earth metal or their mixtures, the optimized selection is KOH, NaOH aqueous solution or their mixture, or selected from the group consisting of carbonate, sulfate, fluoride salt aqueous solution of the alkali metal or alkaline earth metal or mixtures thereof, or the mixture mixed with their hydroxide aqueous solution; the diaphragm is selected from the group of materials consisting of hydrated cellulose film, polyethylene graft film, cellophane paper, nylon cloth, hydrated cellulose paper, cotton paper, potassium titanate paper, polyethylene felt, zirconia fiber paper, vinylon non-woven fabric or mixtures of a composite membrane thereof. 
     
     
         6 . The electrochemical method for producing and storing hydrogen described according to  claim 1 , wherein the hydrogen-generating electrode is made of pure metal, metal oxide, and the composite materials made by the alloy or metal and alloy and oxide, by using several physical and chemical methods such as electroplating, composite plating, thermal decomposition, ion plating, ion implantation, ion sputtering, chemical plating, foamed metal technology, or made by combining two or three kinds of technologies; the hydrogen-generating electrode selected from the group preferably consisting of pure metal such as Co, Fe, Mo, W, Pt, Pd, Ru; oxide such as RuO 2 , TiO 2 , ZrO 2 ; alloy such as Ni—Mo, Ni—B, Ni—P, Ni—NiS, Ni—Pt, Ni—Ru, Co—Mo, Ni-Wo, Ni—Sn, Mo—W, Co—W, Ni-storing-hydrogen alloy, and Ni—P—Co—No—W, Ni—Co—Mo, Ni—Co—Mo—W, Ni—P—Mo—Co, Ni—P—W, Ni—P—Co—Mo—W, Ni—B—Co, Ni—B—Mo, Ni—B—Co—Mo, Ni—B—Co—Mo—W, Ni—B—W, Ni—Co-storing-hydrogen alloy; composite material of the metal or alloy with oxide such as Ni—RuO, Ni—Mo—RuO, Ni—NiS, Ni—Mo—W—RuO 2 . 
     
     
         7 . The electrochemical method for producing and storing hydrogen described according to  claim 1 , wherein the oxygen-generating electrode is made of steel, iron, or nickel by using methods of nickel plating, or sulfur coated nickel plating on structures such as mesh, strip, plate, sheet, foamed metal to treat the surface, or the electrode is any one selected from the group consisting of titanium-base platinum group oxide electrode, iridium system coating titanium electrode, manganese dioxide coating titanium electrode, perovskite type oxide electrode. 
     
     
         8 . The electrochemical method for producing and storing hydrogen described according to  claim 1 , wherein the hydrogen-generating electrode that is concurrently as the oxygen-generating electrode described is made of steel, iron, nickel by using methods of the nickel plating or sulfur coated nickel plating on structures such as mesh, strip, plate, sheet and foamed metal to treat the surface. 
     
     
         9 . The electrochemical method for producing and storing hydrogen described according to  claim 1 , wherein the hydrogen-generating electrode, oxygen-generating electrode, and hydrogen-producing electrode that is concurrently as the oxygen-generating electrode described are structured flaky, meshy, porous, gas diffusion electrode. 
     
     
         10 . The electrochemical method for producing and storing hydrogen described according to  claim 3 , wherein the zinc electrode is a flaky or porous powder structure, and preferably the porous powder structure. 
     
     
         11 . The electrochemical method for producing and storing hydrogen described according to  claim 2 , wherein the hydrogen-generating electrode is made of pure metal, metal oxide, and the composite materials made by the alloy or metal and alloy and oxide, by using several physical and chemical methods such as electroplating, composite plating, thermal decomposition, ion plating, ion implantation, ion sputtering, chemical plating, foamed metal technology, or made by combining two or three kinds of technologies; the hydrogen-generating electrode selected from the group preferably consisting of pure metal such as Co, Fe, Mo, W, Pt, Pd, Ru; oxide such as RuO 2 , TiO 2 , ZrO 2 ; alloy such as Ni—Mo, Ni—B, Ni—P, Ni—NiS, Ni—Pt, Ni—Ru, Co—Mo, Ni-Wo, Ni—Sn, Mo—W, Co—W, Ni-storing-hydrogen alloy, and Ni—P—Co—No—W, Ni—Co—Mo, Ni—Co—Mo—W, Ni—P—Mo—Co, Ni—P—W, Ni—P—Co—Mo—W, Ni—B—Co, Ni—B—Mo, Ni—B—Co—Mo, Ni—B—Co—Mo—W, Ni—B—W, Ni—Co-storing-hydrogen alloy; composite material of the metal or alloy with oxide such as Ni—RuO, Ni—Mo—RuO, Ni—NiS, Ni—Mo—W—RuO 2 . 
     
     
         12 . The electrochemical method for producing and storing hydrogen described according to  claim 2 , wherein the oxygen-generating electrode is made of steel, iron, or nickel by using methods of nickel plating, or sulfur coated nickel plating on structures such as mesh, strip, plate, sheet, foamed metal to treat the surface, or the electrode is any one selected from the group consisting of titanium-base platinum group oxide electrode, iridium system coating titanium electrode, manganese dioxide coating titanium electrode, perovskite type oxide electrode. 
     
     
         13 . The electrochemical method for producing and storing hydrogen described according to  claim 2 , wherein the hydrogen-generating electrode that is concurrently as the oxygen-generating electrode described is made of steel, iron, nickel by using methods of the nickel plating or sulfur coated nickel plating on structures such as mesh, strip, plate, sheet and foamed metal to treat the surface. 
     
     
         14 . The electrochemical method for producing and storing hydrogen described according to  claim 2 , wherein the hydrogen-generating electrode, oxygen-generating electrode, and hydrogen-producing electrode that is concurrently as the oxygen-generating electrode described are structured flaky, meshy, porous, gas diffusion electrode.