Fig. 1.
Scheme of delafossite analog of AxBO2H1-x (A, Ag; B, Co and Fe; x, 1/4) based on the mutation of the delafossite and oxyhydroxide and their OER activity. (A–D) The atomic structures (side view) of different configurations: AgCoO2 (A), CoOOH (B), AgxCoO2H1-x (x = 1/4) (C), and AgxFeyCo1-yO2H1-x (x = 1/4, y = 1/4) (D), and the top views of the atomic structures are shown below the panels. (E–G) The electronic configurations and the corresponding crystal fields: low-spin Co3+ (E), high-spin Co3+ (F), and high-spin Fe3+ (G). (H–J) The calculated ∆G of the OER: CoOOH (H), Ag1-xCoO2Hx (I), and AgxFeyCo1-yO2H1-x (J). Here, the white, red, blue, green, and silver balls represent H, O, Co, Fe, and Ag atoms, respectively. The dark blue, sky blue, and green polygons stand for the octahedral crystal fields of the original Co–O, stretched Co–O, and Fe–O, respectively.