effects of fe2o3 addition and mechanical activation on thermochemical heat storage properties of the co3o4/coo system

Effects of fe2o3 addition (2-20 wt%) with 1 h mechanical activation on redox reactions of co3o4 were studied by tg/dsc, sem, and xrd analyses. the results showed that a fe2o3 addition from 2 to 15 wt% increases the oxygen release from 1.4 to 3.4 wt% and decreases the reduction onset temperature from 1030 to 960 ℃, while it increases the oxygen uptake value and re-oxidation onset temperature respectively from 1.5 to 3.3 wt% and from 930 to 1010 °c. the increase in iron oxide to 20 wt% resulted in loss of heat storage properties due to significant reduction in oxygen release and uptake. moreover, tg/dsc analyses revealed that reduction enthalpy of as-received co3o4, 1 h ball milled co3o4, and 1 h ball milled co3o4-15% fe2o3 are 622, 496, and 895 kj/kg, respectively. phase identification and tg experiments under argon atmosphere demonstrated that fe2o3 participates in the reduction process. furthermore, adding 15 wt% of iron oxide to cobalt oxide and 1 h mechanical activation improved the redox cyclability of cobalt oxide.