Ordered Ni–N–C Nanofibers Enable Spatially Uniform H+/CO2 Distribution for Voltage-Tolerant CO2-to-CO Electroreduction

Single-atom catalysts (SACs) hold great promise for the electrochemical reduction of CO 2 to CO; however, the high selectivity is typically restricted within a narrow potential window, limiting their practical implementation. In this study, Ni–N–C catalysts were supported on ordered and disordered carbon nanofiber membranes (denoted as o-NiNC and d-NiNC, respectively) via electrospinning to elucidate the effect of nanofiber alignment on CO 2 reduction activity. The results demonstrate that o-NiNC catalysts allow for spatially uniform H + /CO 2 delivery and consumption, thereby mitigating the selectivity variations arising from uneven spatial distribution of reactants. As a result, the o-NiNC catalysts achieve a CO Faradaic efficiency (FE) of 98.5% at −1.0 V and maintain an FE above 90% across a broad potential range (−0.6 to −1.6 V). This work provides new insights into the rational design of high-performance CO 2 reduction electrocatalysts through geometric engineering.