Targeting Synthesis of Diatomic Catalysts by Selective Etching and Sequential Adsorption of Metal Atom

Diatomic catalysts featuring a tunable structure and synergetic effects hold great promise for various reactions. However, their precise construction with specific configurations and diverse metal combinations is still challenging. Here, a selective etching and metal ion adsorption strategy is proposed to accurately assign a second metal atom (M2) geminal to the single atom site (M1–Nx) for constructing diatomic sites (e.g., Fe–Pd, Fe–Pt, Fe–Ru, Fe–Zn, Co–Fe, Co–Ni, and Co–Cu). In this strategy, hydrogen peroxide selectively etches the positively charged carbon atoms near the M1–Nx moiety (denoted as α-C) and produces vacancy, which could trap the M2 at the subsequent adsorption step. These catalysts show optimized electronic structure and enhanced oxygen reduction activity compared to single-site counterparts, and the representative Fe–Pd–NC and Co–Fe–NC catalysts stand as the most active oxygen reduction reaction catalysts (half-wave potential of 0.92 and 0.91 V, respectively). The selective etching of α-C in single-atom catalysts reported here represents a new post-treatment strategy for the targeting synthesis of diatomic sites.