Tuning d-Band Structure of CuII in Coordinated Polymer via d-π Conjugation for Improving CO2 Electroreduction Selectivity toward C2 Products.

Abstract

Copper-coordinated catalysts are reported to be effective for electrocatalytic CO2 reduction reaction (CO2 RR) to C2 products but suffer from low selectivity. Herein a strategy was developed to tune the d-band structure of CuII via coordinating with aromatic ligands to form Cu-based conjugated polymers for CO2 RR to C2 chemicals. The catalysts derived from copper chloride coordinating with tetraminobenzoquinone (TABQ) and with 1,2,4,5-benzenetetramine possessed high-density and compact Cu single-atom sites and displayed high activity for CO2 RR to C2 products. Especially, Cu-TABQ exhibited a maximum C2 faradaic efficiency of 63.2 % with a current density of 423 mA cm-2 at -1.17 V (vs. reversible hydrogen electrode). Density functional theory calculations indicated that the TABQ linker possessing C=O groups significantly widened the d-band of coordinated CuII , which facilitated binding of *CO intermediate on the catalyst and thus enhanced C-C coupling. This work provides mechanistic insight into the CuII -coordinated polymers for CO2 RR with high selectivity toward C2 products.