Metal-Organic Polyhedra (MOPs) as emerging class of metal-organic frameworks for CO2 photocatalytic conversions: Current trends and future outlook

Abstract

Metal-Organic Polyhedra (MOP) is a relatively new class of metal-organic frameworks, and their budding application as photocatalysts for catalytic conversion of CO2 with high activity and specificity has been reported in the last five years. However, challenges such as catalytic stability, the deactivation of active sites, and reusability concerns limit their industrial application. To mitigate these challenges, post-synthetic modifications (PSM) of MOP have proven useful without significantly altering the catalytic activity of the metal-organic framework. PSM can occur at metal centres, organic linkers, and via salt metathesis/ion exchange. These three scenarios are discussed, and useful photosensitive modifiers are highlighted. This study also highlights the potential for homogeneous catalysts to form chemical bonds with or within heterogeneous MOPs to improve CO2 transformation to CO and formic acid with 131 h-1 and 76 h-1 turnover frequencies, respectively. There is a surge in published articles on the application of functionalized MOPs in energy storage, sensors, and membrane separation in the form of hydrogels, dendrimers, hybrid composites and other heterostructures. This suggests the enormous potential of MOPs as building blocks for porous materials. Hence, the development of stable MOP via one-pot synthesis techniques and industrial-scale applications in green energy production and environmental remediation should be further investigated.

Keywords

• CO2 conversion
• Heterostructures
• Metal-organic polyhedra
• Photocatalysis
• Post-synthetic modifications