Efficient acidic oxygen evolution reaction electrocatalyzed by iridium-based 12L-perovskites comprising trinuclear face-shared IrO6 octahedral strings
Development of cost-effective and highly active oxygen evolution catalysts operating well in acidic media is a critical challenge in proton exchange membrane water electrolysis . Herein, we present a class of iridium-based 12L-perovskites (Ba 4 MIr 3 O 12 ; M = Pr, Bi, Nb) as novel low-iridium electrocatalysts for oxygen evolution reaction under acidic conditions. These 12L-perovskites contain trinuclear face-shared IrO 6 octahedral strings—unique subunits that are not found in the previously-reported iridium-based electrocatalysts . The catalytic activities of 12L-perovskites (Ba 4 MIr 3 O 12 ) are found to be related to the location of O 2 p -band center, which is influenced by the B-site nonprecious element ( i.e. , Pr, Bi or Nb). Our experimental results show that Ba 4 PrIr 3 O 12 is the most active electrocatalyst among the materials we synthesize, and contains 55% less iridium than the benchmark catalyst IrO 2 , while exhibiting higher catalytic activity. In the presence of Ba 4 PrIr 3 O 12 , transient leaching process of Ba and Pr takes place during electrochemical process , contributing to the surface reconstruction of the pristine catalysts. Further experimental results reveal that the formation of under-coordinated IrO x -rich surface and easier generation of active intermediate Ir V are mainly responsible for the good activity of Ba 4 PrIr 3 O 12 .
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