Carbothermal reduction assisted by hydrogenation treatment for preparing single-phase CeC₂ nanoscale powders

Abstract

Single-phase CeC2 powders can be successfully prepared through the carbothermal reduction assisted by hydrogenation treatment (CRHT) using 20-50 nm CeO2 as cerium source and 100-200 nm carbon black as carbon source. During the hydrogenation process, the interaction of CeO2 with H2 leads to a partial valence reduction of Ce ions, yielding a partially anoxic phase (CeO1.675) and a hydrogenated phase (CeH2). CeO1.675 can increase the oxygen vacancies required in the reaction process, while CeH2 can produce gas-phase reductant H2 at the reaction temperature, which together promotes the reduction reaction. The results show that the CRHT can obtain single-phase CeC2 powders at a temperature of 1550 ℃, which is 100 ℃ lower than its theoretical temperature. For the preparation of CeC2 powders, the CRHT is a low-temperature and efficient method.