Hydrogen separation using proton-conducting perovskites

Two methods of hydrogen separation using proton-conducting perovskites, electrochemical hydrogen pumping with proton-conducting electrolytes and hydrogen sieving through protonic-electronic mixed conductors, are stated. In the former case, high temperature proton conductors (HTPCs) enable the hydrogen transport by external application of electricity. In the latter case, it is a fundamental concern how the protonic and electronic charge carriers coexist in oxides to allow hydrogen permeation. Experimental results and the problems for future investigations are discussed. (c) 2005 Elsevier B.V. All rights reserved.