Structural features and catalytic properties of AgFeO₂ binary oxide in the СО oxidation reaction

Structural features and catalytic properties of silver and iron binary oxide AgFeO₂ in the СО oxidation reaction are investigated. Binary oxide samples are obtained by coprecipitation and hydrothermal synthesis techniques at different temperatures. In the temperature range of 140-180 °С, well crystallized AgFeO₂ particles are formed primarily with a 3R polytype structure (~90%), and at T = 60-120 °С highly dispersed particles with a developed defect structure are obtained. It is shown that calculated X-ray diffraction patterns of models of delafossite crystals with microtwinning are well consistent with experimental curves. Binary oxide AgFeO₂ samples demonstrate a high activity in the СО oxidation reaction, which increases with a decrease in the synthesis temperature. The highest specific catalytic activity is found for highly dispersed samples with a developed defect structure. During catalytic experiments the effect of the reaction medium modifies the surface composition due to the partial exit of silver from the delafossite structure.