Ni Single Atoms Embedded in Graphene Nanoribbon Sieves for High‐Performance CO2 Reduction to CO

Abstract Ni single‐atom catalysts (SACs) are appealing for electrochemical reduction CO2 reduction (CO2RR). However, regulating the balance between the activity and conductivity remains a challenge to Ni SACs due to the limitation of substrates structure. Herein, the intrinsic performance enhancement of Ni SACs anchored on quasi‐one‐dimensional graphene nanoribbons (GNRs) synthesized is demonstrated by longitudinal unzipping carbon nanotubes (CNTs). The abundant functional groups on GNRs can absorb Ni atoms to form rich Ni–N4–C sites during the anchoring process, providing a high intrinsic activity. In addition, the GNRs, which maintain a quasi‐one‐dimensional structure and possess a high conductivity, interconnect with each other and form a conductive porous framework. The catalyst yields a 44 mA cm−2 CO partial current density and 96% faradaic efficiency of CO (FECO) at −1.1 V vs RHE in an H‐cell. By adopting a membrane electrode assembly (MEA) flow cell, a 95% FECO and 2.4 V cell voltage are achieved at 200 mA cm−2 current density. This work provides a rational way to synthesize Ni SACs with a high Ni atom loading, porous morphology, and high conductivity with potential industrial applications.