Solvation Effect‐Determined Mechanisms of Cation Exchange Reactions for Efficient Multicomponent Nanocatalysts

Abstract Cation exchange (CE) reaction is a classical synthesis method for creating complex structures. A lock of study on intrinsic mechanism limits its understanding and practical application. Using X‐ray absorption spectroscopy, we observed that the evolution from Ru−Cl to Ru−O/OH occurs during the CE between K 2 RuCl 6 and CoSn(OH) 6 in aqueous solution, while CE between K 2 PtCl 6 and CoSn(OH) 6 is inhibited due to the failure of structural evolution from Pt−Cl to Pt−O/OH. Theoretical simulations imply that the interaction between Ru−O and CoSn(OH) 6 with Co vacancy (CoV Co Sn(OH) 6 ) endows the electron transfer, as a result of strengthened adsorption on CoV Co Sn(OH) 6 . Moreover, this mechanism is validated for CE between K 2 RuCl 6 and ASn(OH) 6 (A=Mg, Ca, Mn, Co, Cu, Zn), and CE between K 2 PdCl 6 /Na 3 RhCl 6 /K 2 IrCl 6 and CoSn(OH) 6 . Impressively, the Pt‐free CoRuSn(OH) x produced via CE displays a mass activity and a power density of 15.0 A mg Ru −1 and 11.6 W mg Ru −1 , respectively, for anion exchange membrane fuel cell (AEMFC) exceeding the values of commercial PtRu/C (11.8 A mg Ru+Pt −1 and 9.0 W mg Ru+Pt −1 ). This work, for the first time, reveals the intrinsic mechanism of CE as structural evolution of target ion breaking through the traditional classic etch‐adsorption mechanism and will promote fundamental research and practical application in various fields.