Ligand Engineering in Nickel Phthalocyanine to Boost the Electrocatalytic Reduction of CO₂

Abstract

Abstract Designing and synthesizing efficient molecular catalysts may unlock the great challenge of controlling the CO 2 reduction reaction (CO 2 RR) with molecular precision. Nickel phthalocyanine (NiPc) appears as a promising candidate for this task due to its adjustable Ni active‐site. However, the pristine NiPc suffers from poor activity and stability for CO 2 RR owing to the poor CO 2 adsorption and activation at the bare Ni site. Here, a ligand‐tuned strategy is developed to enhance the catalytic performance and unveil the ligand effect of NiPc on CO 2 RR. Theoretical calculations and experimental results indicate that NiPc with electron‐donating substituents (hydroxyl or amino) can induce electronic localization at the Ni site which greatly enhances the CO 2 adsorption and activation. Employing the optimal catalyst—an amino‐substituted NiPc—to convert CO 2 into CO in a flow cell can achieve an ultrahigh activity and selectivity of 99.8% at current densities up to −400 mA cm −2 . This work offers a novel strategy to regulate the electronic structure of active sites by ligand design and discloses the ligand‐directed catalysis of the tailored NiPc for highly efficient CO 2 RR.