Visible‐Light‐Driven CO₂ Reduction Using Imidazole‐Based Metal–Organic Frameworks as Heterogeneous Photocatalysts

Abstract The development of robust, efficient, and cost‐effective heterogeneous photocatalysts for visible light‐driven CO2 reduction continues to be a significant challenge in the quest for sustainable energy solutions. As a result, increasing attention is being directed towards the exploration of high‐performance photocatalysts capable of converting CO2 into valuable chemical feedstocks. In context to this, Imidazolate Frameworks Potsdam (IFPs), a class of metal‐organic frameworks (MOFs), can be a promising candidate for CO2 photoreduction due to their ease of synthesis, use of low‐cost, earth‐abundant metals, and high chemical and thermal stability. In this study, we report the solvothermal synthesis of Zn(II)‐ and Co(II)‐based IFPs, specifically IFP‐1(Zn) and IFP‐5(Co), for photocatalytic CO2 reduction. Moreover, we demonstrate the enhanced photocatalytic activity of redox‐innocent Zn‐based IFP‐1 by partially substituting Zn(II) with redox‐active Co(II) in IFP‐1(Zn), resulting in the formation of a bimetallic photocatalyst, IFP‐1(Zn/Co). The metal‐exchanged IFP‐1(Zn/Co) exhibited significantly improved CO evolution (637 μmol g−1 in 1 hour), compared to the pristine IFP‐1(Zn) (29 μmol g−1). Notably, among all the prepared photocatalysts, IFP‐5(Co) outperformed both the systems, achieving a CO evolution of 1174 μmol g−1 within 1 hour, due to the presence of catalytic cobalt sites. In addition, through the combination of photophysical and electrochemical studies, along with DFT calculations, we have proposed a plausible mechanism for the photocatalytic CO2 reduction.