Enhanced oxygen reduction reaction with nano-scale pyrochlore bismuth ruthenate via cost-effective wet-chemical synthesis

Abstract

Pyrochlore ruthenate oxides are promising electrocatalytic materials for lower temperature solid oxide fuel cell (LT-SOFC) cathodes due to their high catalytic activity toward oxygen reduction reaction (ORR) which is the major rate-limiting step at reduced temperatures (below 750 °C). Here we report for the first time highly pure pyrochlore bismuth ruthenate (Bi₂Ru₂O₇, BRO7) synthesized via a practical and cost-effective glycine–nitrate (GNC) combustion method. The synthesis parameters including glycine to nitrate ratio and calcination conditions were systematically optimized, resulting in nanoparticles with crystallite size of ∼30 nm and significant reduction in synthesis steps. Incorporating the synthesized BRO7 nanoparticles with highly conductive bismuth oxide as an SOFC cathode results in significant enhancement of ORR, showing 9 times lower SOFC cathode area specific resistance, compared to that of BRO7 via conventional solid-state reaction. Thus, this result demonstrates the feasibility of BRO7 nanoparticles via GNC to enhance the ORR for lower temperature SOFC applications.