Total conversion of centimeter-scale nickel foam into single atom electrocatalysts with highly selective CO2 electrocatalytic reduction in neutral electrolyte

To improve the atomic utilization of metals and reduce the cost of industrialization, the one-step total monoatomization of macroscopic bulk metals, as opposed to nanoscale metals, is effective. In this study, we used a thermal diffusion method to directly convert commercial centimeter-scale Ni foam to porous Ni single-atom-loaded carbon nanotubes (CNTs). As expected, owing to the coating of single-atom on porous, highly conductive CNT carriers, Ni single-atom electrocatalysts (Ni-SACs) exhibit extremely high activity and selectivity in CO2 electroreduction (CO2RR), yielding a current density of > 350 mA/cm2, a selectivity for CO of > 91% under a flow cell configuration using a 1 M potassium chloride (KCl) electrolyte. Based on the superior activity of the Ni-SACs electrocatalyst, an integrated gas-phase electrochemical zero-gap reactor was introduced to generate a significant amount of CO current for potential practical applications. The overall current can be increased to 800 mA, while maintaining CO Faradaic efficiencies (FEs) at above 90% per unit cell. Our findings and insights on the active site transformation mechanism for macroscopic bulk Ni foam conversion into single atoms can inform the design of highly active single-atom catalysts used in industrial CO2RR systems.