Manipulating local environment and spin-state of single-atom via helical structure for CO2 electroreduction to formate

The underappreciated role of supports has severely constrained the modification of single-atom catalysts. It’s important to develop a strategy for achieving a strong synergy between catalytic structures and active sites. Here, we devise a structure-inducing method involving the manipulation of the chemical reaction environment and spin-state of Cu single-atom with helical carbon nanotube (HCNT) for CO₂ efficient electroreduction to formate. Utilizing in situ characterization and finite element simulation, we find that the helical structure effectively enriches HCO₃⁻ and OH⁻ on the surface of Cu-N₂O₂/HCNT catalyst during electrocatalytic CO₂ reduction, creating a favorable interfacial environment for formate generation. Magnetic characterizations and theoretical calculations reveal spin polarization of Cu-N₂O₂ sites, yielding readily polarized magnetic moments. Consequently, a spin-ordered phase emerges on the surface of Cu-N₂O₂/HCNT under a magnetic field, enhancing formate selectivity. Impressively, Cu-N₂O₂/HCNT achieves 93.6 % formate selectivity at −0.80 V vs. RHE under 200 mT. Under an in situ magnetic field, it maintains over 80 % formate selectivity at −175 mA/cm² for 100 h. Our findings offer novel insights into single-atom catalyst modification.