Constructing a metal-free 2D covalent organic framework for visible-light-driven photocatalytic reduction of CO2: a sustainable strategy for atmospheric CO2 utilization

Abstract

A 2D polyimide-linked covalent organic framework (COF) is developed as a stable and efficient porous photocatalyst, associated with a very low band gap energy of 2.2 eV. Different characterization studies have been conducted to identify the structural and morphological features of the material. The photocatalyst shows CO₂ reduction to formic acid, formaldehyde and methanol with a maximum production rate of 30.62 mol g_cat⁻¹ h⁻¹, 23.1 mol g_cat⁻¹ h⁻¹ and 46.67 mmol g_cat⁻¹ h⁻¹, respectively in the absence of any metal in the photocatalytic system. The catalyst is recyclable for multiple reaction cycles without losing its structural stability as well as its efficiency. Hence, the current study affords a viable path for exploring the application of COFs to improve photocatalytic processes which can be used to expand photo-induced CO₂ conversion in solar fuel-based devices.