Partial Exsolution Enables Superior Bifunctionality of Ir@SrIrO3 for Acidic Overall Water Splitting

Abstract The pursuit of efficient and durable bifunctional electrocatalysts for overall water splitting in acidic media is highly desirable, albeit challenging. SrIrO3 based perovskites are electrochemically active for oxygen evolution reaction (OER), however, their inert activities toward hydrogen evolution reaction (HER) severely restrict the practical implementation in overall water splitting. Herein, an Ir@SrIrO3 heterojunction is newly developed by a partial exsolution approach, ensuring strong metal‐support interaction for OER and HER. Notably, the Ir@SrIrO3‐175 electrocatalyst, prepared by annealing SrIrO3 in 5% H2 atmosphere at 175 °C, delivers ultralow overpotentials of 229 mV at 10 mA cm−2 for OER and 28 mV at 10 mA cm−2 for HER, surpassing most recently reported bifunctional electrocatalysts. Moreover, the water electrolyzer using the Ir@SrIrO3‐175 bifunctional electrocatalyst demonstrates the potential application prospect with high electrochemical performance and excellent durability in acidic environment. Theoretical calculations unveil that constructing Ir@SrIrO3 heterojunction regulates interfacial electronic redistribution, ultimately enabling low energy barriers for both OER and HER.


Figure S1 .
Figure S1.Schematic diagram of the synthesis of partially exsolved Ir@SrIrO3

Figure S5 .
Figure S5.Fitting result of corresponding structure of SrIrO3 in a) R space, b) k space.

Figure S6 .
Figure S6.Fitting result of corresponding structure of Ir@SrIrO3-175 in a) R space, b)

Figure S15 .
Figure S15.Theoretical structural models of OER intermediates adsorbed on Ir. (Ir atom:

Figure S16 .
Figure S16.Theoretical structural models of OER intermediates adsorbed on SrIrO3-Ir

Figure S17 .
Figure S17.Theoretical structural models of OER intermediates adsorbed on Ir-SrIrO3

Figure S18 .
Figure S18.Theoretical structural models of HER intermediate (H*) adsorbed on (a)

Table S3 .
Comparation of the overpotentials of the OER and HER over Ir@SrIrO3-175 with the reported electrocatalysts at 10 mA cm -2 in acid media.