Boosting oxygen evolution reaction by enhanced intrinsic activity in Ruddlesden−Popper iridate oxides

A prototypical family of Ruddlesden−Popper (R-P) iridate oxides Srn+1IrnO3n+1 (n = 1, 2, and ∞) was investigated to intensify systematic understanding of the intrinsic activity of the bulk crystal structure on oxygen evolution reaction (OER). Compared with IrO2, these oxides contain less iridium and show higher catalytic activity. Especially, Sr3Ir2O7 (n = 2) displays enhanced activity of the optimum that is programmed by the dimensionality of the bulk crystal structure. As n decreased, a distinct d-band center downshift leads to weakened adsorption of oxygen intermediates, which accelerates the kinetics. Calculations also reveal an elevated conductivity in overall values from n = 1, 2 to ∞. Both the increased conductivity and optimized binding energy contribute the exceptional OER activity of Sr3Ir2O7. This work suggests a significant advance in understanding the relationship between intrinsic activity and the bulk crystal structure of R-P oxides.