STOICHIOMETRY OF H-2 EVOLUTION IN THE 2-STEP WATER-SPLITTING BY A CIO-LAYERED NI(II)-FERRITE

The stoichiometry of H-2 evolution in the 2-step water splitting with the ClO-layer (carbon iron oxide-layer) of the Ni(II)-ferrite (step 1: activation step, where the oxygenis released from ClO-layer; step 2: H-2 evolution step by water splitting with the activated CIO-layer), w hich can be repeated at 300 degrees C, has been studied. The H-2, evol ution profile showed that there exist two types of H-2 evolution react ions (Types I and II). Type I is water splitting by the activated form of ClO-layer (alpha), (n=repetition number) where the activated form changes to the original form (beta(n)) Type II is the H-2 evolution fr om water by the oxidation of ClO-layer, where the original CIO-layer f orm (beta(n) changes to a slightly oxidized form (beta(n+)). The measu rement of the O-2 volume in the activation step (ClO-layer (beta(n))-- >ClO-layer (alpha(n))+1/20(2)) showed that about 0.4-0.8 moles of the oxygen were released from the ClO-layer (beta(n)) by passing O-2-free Ar gas at 300 degrees C, when one mole of H-2 gas was evolved by the T ype I reaction of the activated ClO-layer (ClO-layer (alpha)) with wat er at 300 degrees C. The reaction mechanism for the activation of the ClO-layer is discussed. (C) 1997 International Association for Hydroge n Energy.