Solid-Diffusion Synthesis of Single-Atom Catalysts Directly from Bulk Metal for Efficient CO ₂ Reduction

Electroreduction of CO ₂ into value-added products is an effective approach to remit the environmental and energy issues. However, the development of an effective, accessible, and simple method for mass production of electrocatalyst is challenging. Herein, we demonstrate the solid-state diffusion between the N-doped carbon phase and bulk Ni metal can be utilized to synthesize hierarchical, self-supported, and atomistic catalyst. Strikingly, this hierarchical catalyst is programmable and scalable to meet the industrial demand and can be directly used as a binder-free electrode toward the CO ₂ electroreduction, delivering a state-of-the-art current density of 48.66 mA cm ⁻² at −1.0 V versus reversible hydrogen electrode (RHE) and high faradic efficiency of 97% to CO. The selectivity can be retained over 90% in a wide range of working potential of −0.7 to −1.2 V versus RHE. This solid-state diffusion strategy presents great potential to produce hierarchical and atomistic catalysts at industrial levels. The excessive emission of CO ₂ through massive fossil fuel consumption results in serious environmental issues. There is an urgent need to convert CO ₂ into chemical fuels to mitigate atmospheric CO ₂ levels and alleviate the energy crisis. Therefore, the design and synthesis of high-performance and flexible self-supported electrocatalysts for CO ₂ reduction are highly desirable to realize high-efficiency practical devices. Herein, we successfully synthesize a hierarchical and atomistic catalyst through a solid-state diffusion strategy. This synthesis is initiated by the direct solid-state diffusion of Ni atoms from bulk Ni foil into the contacted carbon shell. Catalyzed by the Ni “seeds” derived from the bulk Ni, self-supported nanotube fiber-based carbon paper decorated by abundant isolated atomistic Ni sites are successfully “cultivated.” This hierarchical catalyst is programmable and scalable to meet the industrial demand for CO ₂ conversion.