Metal‐Free Guanidium‐Based Ionic Covalent Organic Polymer as an Efficient Catalyst for Visible‐Light‐Assisted CO ₂ Reduction

Abstract To address the growing greenhouse effect, one emerging focus in environmental remediation is the development of efficient porous adsorbents capable of rapidly capturing atmospheric CO 2 . The present study introduces a synthetic approach for the sustainable production of formic acid via visible‐light‐driven CO 2 reduction employing a guanidinium‐based ionic covalent organic polymer (Tp‐TAG‐Cl iCOP) as a metal‐free photocatalyst. The nitrogen‐rich TpTAG‐Cl iCOP, synthesized in an economically viable and scalable manner using the Schiff base condensation procedure, was thoroughly characterized by analytical techniques including XRD, FT‐IR, N 2 adsorption–desorption studies, FESEM, HRTEM, XPS, and solid‐state UV–visible (vis) spectroscopy. It exhibits a narrow bandgap of 2.0 eV, facilitating effective absorption of visible light and resulting in high photocatalytic performance. Under optimal circumstances, the catalyst attained a remarkable formic acid production rate of 21 mol g −1 h −1 and a methanol production rate of 0.25 mol g −1 h −1 with a white LED light source of 20 W. The light dependency reaction was confirmed, and the photocatalyst exhibited excellent stability and reusability over multiple cycles. These results highlight a promising strategy for environmentally friendly CO 2 conversion using metal‐free catalyst.