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Abstract:
If different active sites in a catalyst have optimal binding to different reaction intermediates and short reaction paths among them,} they may work cooperatively to enhance the oxygen evolution reaction (OER) activity. Based on this design principle{,} in this study{,} we start with a B-site ordered double perovskite Sr2FeMoO6−δ with poor OER activity as the host material to fulfill the requirement of a short pathway{,} and then{,} replace Mo with Ni and Fe with Co to optimize the synergistic interplay of the multi-active sites. Replacing Mo with Ni indeed dramatically enhances the OER activity and structural/operating stability. Further improvement in OER performance is realized by partial substitution of Fe with Co{,} leading to the development of a material with the nominal composition of Sr2Fe0.8Co0.2Mo0.65Ni0.35O6−δ{,} which outperforms the noble metal oxide IrO2 and is better than most of the electrocatalysts developed based on a single descriptor{,} such as Ba0.5Sr0.5Co0.8Fe0.2O3−δ (eg occupancy close to unity){,} PrBaCo2O5+δ (O 2p-band center relative to the Fermi level){,} and La0.5Sr0.5CoO3−δ (charge-transfer energy) in many aspects. As a universal method{, combined structural and compositional tuning to create a cooperative effect among different active sites for intermediate adsorption and reaction in an ordered structure may provide a new way for the design of superior electrocatalysts for various applications.
