Lowering the kinetic barrier via enhancing electrophilicity of surface oxygen to boost acidic oxygen evolution reaction

The acidic oxygen evolution reaction (OER) is essential for many renewable energy conversion and storage technologies. However, the high energy required to break the strong covalent O-H bond of H2O in acidic media results in sluggish OER kinetics. Here, we report the critical role of iron in a new family of iron-containing yttrium ruthenate (Y2-xFexRu2O7-δ) electrocatalysts in highly increasing the electrophilicity of surface oxygen, leading to a significant reduction of the kinetics barrier by 33%, thus an exceptional OER mass activity of 1,021 A·gRu−1 up to 12.4 and 7.7 times that of Y2Ru2O7-δ and RuO2, respectively. Introducing iron reduces the Mulliken atomic charge on the O sites in the generated Ru-O-Fe structure, thereby facilitating the acid-base nucleophilic assault from H2O and reducing the free energy on the rate-determining step of OER. This work provides an effective strategy to reduce the kinetics barrier to achieve highly efficient and economic OER in acidic conditions. [Display omitted] •The charge transfer from O and Ru to Fe is demonstrated in the Ru-O-Fe structure•Iron incorporation increases the electrophilicity of surface oxygen from catalysts•Iron incorporation increases the water adsorption ability of the catalysts•Iron incorporation reduces the energy barrier for water dissociation Oxygen evolution reaction (OER) is the primary reaction occurring at the anode in many electrochemical energy conversion processes. Despite more favorable kinetics for alkaline OER, acidic OER is more applicable to commercialization because of the successful development and large-scale applications of proton exchange membranes. However, the large kinetic barrier for acidic OER from surface water adsorption and dissociation has been long neglected, which limits the catalytic performance of electrocatalysts for acidic OER. The development of acid-resistant electrocatalysts with the capability to significantly reduce the kinetics barrier to achieve efficient OER remains a great challenge. Here, enhancing the electrophilicity of surface oxygen via iron incorporation assists water adsorption and dissociation, providing an effective strategy to reduce the kinetics barrier for efficient and economic OER in acidic conditions. Tremendous energy is required to break the strong covalent O-H bond of H2O in acidic media, resulting in sluggish OER kinetics. Herein, the authors report a one-stone-two-birds strategy to effectively enhance the electrophilicity of surface