Rational Fabrication of Low‐Coordinate Single‐Atom Ni Electrocatalysts by MOFs for Highly Selective CO 2 Reduction

Single‐atom catalysts (SACs) have attracted tremendous interests due to their ultrahigh activity and selectivity. However, the rational control over coordination microenvironment of SACs remains a grand challenge. Herein, a post‐synthetic metal substitution (PSMS) strategy has been developed to fabricate single‐atom Ni catalysts with different N coordination numbers (denoted Ni‐N x ‐C) on pre‐designed N‐doped carbon derived from metal‐organic frameworks. When served for CO 2 electroreduction, the obtained Ni‐N 3 ‐C catalyst achieves CO Faradaic efficiency (FE) up to 95.6 %, much superior to that of Ni‐N 4 ‐C. Theoretical calculations reveal that the lower Ni coordination number in Ni‐N 3 ‐C can significantly enhance COOH* formation, thereby accelerating CO 2 reduction. In addition, Ni‐N 3 ‐C shows excellent performance in Zn–CO 2 battery with ultrahigh CO FE and excellent stability. This work opens up a new and general avenue to coordination microenvironment modulation (MEM) of SACs for CO 2 utilization.