The invention belongs to the technical field of water
electrolysis, and particularly relates to a two-
step method and device for producing
hydrogen through water
electrolysis on the basis of a three-
electrode system. According to the device, an electrolytic bath comprises a
hydrogen evolution
catalysis electrode, an
oxygen evolution
catalysis electrode and a
nickel hydroxide electrode. According to the method, water molecules are electrochemically reduced to
hydrogen gas on the surface of the
hydrogen evolution catalysis electrode, a Ni(OH)2 electrode is electrochemically oxidized to form a NiOOH electrode at the same time, and electrons flow to the
hydrogen evolution catalysis electrode from the Ni(OH)2 electrode through an
external circuit in the process; the NiOOH electrode is electrochemically reduced to the Ni(OH)2 electrode, hydroxyl ions are electrochemically oxidized to form
oxygen gas on the surface of the
oxygen evolution catalysis electrode, and the electrons flow to the NiOOH electrode from the
oxygen evolution catalysis electrode through the
external circuit in the process. According to the device and the method, the
hydrogen production step and the oxygen production step which are synchronous in conventional water
electrolysis are effectively separated, the high-purity hydrogen gas can be prepared without any diaphragms through the electrolysis device because the
hydrogen production step and the oxygen production step are completely separated, and therefore the cost of producing the hydrogen through water electrolysis is lowered further.