Enzyme-Inspired Microenvironment Engineering of a Single-Molecular Heterojunction for Promoting Concerted Electrochemical CO2 Reduction

Challenges remain in the development of novel multifunctional electrocatalysts and their industrial operation on low-electricity pair-electrocatalysis platforms for the carbon cycle. Herein, an enzyme-inspired single-molecular heterojunction electrocatalyst ((NHx)(16)-NiPc/CNTs) with specific atomic nickel centers and amino-rich local microenvironments for industrial-level electrochemical CO2 reduction reaction (eCO(2)RR) and further energy-saving integrated CO2 electrolysis is designed and developed. (NHx)(16)-NiPc/CNTs exhibit unprecedented catalytic performance with industry-compatible current densities, approximate to 100% Faradaic efficiency and remarkable stability for CO2-to-CO conversion, outperforming most reported catalysts. In addition to the enhanced CO2 capture by chemisorption, the sturdy deuterium kinetic isotope effect and proton inventory studies sufficiently reveal that such distinctive local microenvironments provide an effective proton ferry effect for improving local alkalinity and proton transfer and creating local interactions to stabilize the intermediate, ultimately enabling the high-efficiency operation of eCO(2)RR. Further, by using (NHx)(16)-NiPc/CNTs as a bifunctional electrocatalyst in a flow cell, a low-electricity overall CO2 electrolysis system coupling cathodic eCO(2)RR with anodic oxidation reaction is developed to achieve concurrent feed gas production and sulfur recovery, simultaneously decreasing the energy input. This work paves the new way in exploring molecular electrocatalysts and electrolysis systems with techno-economic feasibility.

Automated summary

In this study, an enzyme-inspired single-molecular heterojunction electrocatalyst was designed for CO2 reduction reaction and CO2 electrolysis. It exhibits outstanding catalytic performance, outperforming other catalysts, and its mechanism for improving reaction efficiency is revealed through deuterium kinetic isotope effect and proton inventory studies.