Coordination Equilibrium-Assisted Coprecipitation Synthesis of Atomically Dispersed 3d Metal Catalysts

As a frontier of heterogeneous catalysis, single-atom catalysts (SACs) have been extensively studied fundamentally. One obstacle that limits the industrial application of SACs is the lack of a synthetic method that can prepare the catalysts on a large scale. Wet-chemistry methods that are conventionally used to prepare nanoparticle-based industrial catalysts might be a solution. In this work, we report a coprecipitation method using ethylenediaminetetraacetic acid (EDTA) as an equilibrium regulator to synthesize a series of atomically dispersed 3d metal over the Mg(OH)2 support. Mg(OH)2 is formed from the spontaneous dissolution of MgO, which is also the alkali source for coprecipitation to occur. The dissolution–precipitation equilibria of metal hydroxides compete with the coordination equilibria of EDTA-coordinated metal cations, leading to the coprecipitation of loaded metal and Mg2+ cations. The synthetic strategy is applicable for Fe, Co, Ni, and Cu, forming four catalysts that are active for the photodegradation of methylene blue under visible light.