Abstract: A method for producing hydrogen by using different metals includes: providing a metal of lower reduction potential as an anode metal and a metal of higher reduction potential as a cathode metal, then immerse the anode metal and the cathode metal in an electrolyte, while the anode metal and the cathode metal can be combined with appropriate steps before or after being immersed in the electrolyte, whereby hydrogen and side-products generated from a reaction of electrochemistry caused by reduction potential difference between the different metals, that is, the method for producing hydrogen is through spontaneous chemical reaction without extra energy consumption.

Abstract: Methods and apparatuses for in-situ cleaning of semiconductor electroplating electrodes to remove plating metal without requiring !the manual removal of the electrodes from the semiconductor plating equipment. The electrode is placed into the plating liquid and, an electrical current having reverse polarity is passed between the electrode and plating liquid. Plating deposits which have accumulated on the electrode are electrochemically dissolved and removed from the electrode.

Abstract: An improved electrochemical dissolution process for electrochemically dissolving a first metal by simultaneously creating hydrogen evolution at a second metal. The second metal is a metal that has a larger current exchange density for hydrogen evolution than the first metal, and both metals are immersed in an aqueous electrolyte system, wherein the first metal and the second metal are galvanically coupled. By taking measures to reduce inhibition of the hydrogen evolution at the second metal, the rate of dissolution of the first metal is enhanced. The measures to reduce the inhibition comprise selecting suitable temperatures and concentrations of the electrolyte, dividing the electrolyte into two fluids coupled by a selectively permeable device and selecting suitable resistance value for a connecting means electrically connecting the first and the second metal. The invention is particularly useful for removing Zn or Sn from Zn- or Sn-containing steel scrap.