Effect of Micropores of a Porous Coordination Polymer on the Product Selectivity in RuII Complex-catalyzed CO2 Reduction

Unveiling Advancements: Trends and Hotspots of Metal-Organic Frameworks in Photocatalytic CO2 Reduction

Metal-organic frameworks (MOFs) are robust, crystalline, and porous materials featured by their superior CO2 adsorption capacity, tunable energy band structure, and enhanced photovoltaic conversion efficiency, making them highly promising for photocatalytic CO2 reduction reaction (PCO2RR). This study presents a comprehensive examination of the advancements in MOFs-based PCO2RR field spanning the period from 2011 to 2023. Employing bibliometric analysis, the paper scrutinizes the widely adopted terminology and citation patterns, elucidating trends in publication, leading research entities, and the thematic evolution within the field. The findings highlight a period of rapid expansion and increasing interdisciplinary integration, with extensive international and institutional collaboration. A notable emphasis on significant research clusters and key terminologies identified through co-occurrence network analysis, highlighting predominant research on MOFs such as UiO, MIL, ZIF, porphyrin-based MOFs, their composites, and the hybridization with photosensitizers and molecular catalysts. Furthermore, prospective design approaches for catalysts are explored, encompassing single-atom catalysts (SACs), interfacial interaction enhancement, novel MOF constructions, biocatalysis, etc. It also delves into potential avenues for scaling these materials from the laboratory to industrial applications, underlining the primary technical challenges that need to be overcome to facilitate the broader application and development of MOFs-based PCO2RR technologies.

Unlocking Solid-State Organometallic Photochemistry with Optically Transparent, Porous Salt Thin Films

Synthetic porous materials continue to garner attention as platforms for solid-state chemistry and as designer heterogeneous catalysts. Applications in photochemistry and photocatalysis, however, are plagued by poor light harvesting efficiency due to light scattering resulting from sample microcrystallinity and poor optical penetration that arises from inner filter effects. Here we demonstrate the layer-by-layer growth of optically transparent, photochemically active thin films of porous salts. Films are grown by sequential deposition of cationic Zr-based porous coordination cages and anionic Mn porphyrins. Photolysis facilitates the efficient reduction of Mn(III) sites to Mn(II) sites, which can be observed in real-time by transmission UV-vis spectroscopy. Film porosity enables substrate access to the Mn(II) sites and facilitates reversible O2 activation in the solid state. These results establish optically transparent, porous salt thin films as versatile platforms for solid-state photochemistry and in operando spectroscopy.

Flexible Cuprous Triazolate Frameworks as Highly Stable and Efficient Electrocatalysts for CO2 Reduction with Tunable C2 H4 /CH4 Selectivity

Cu-based metal-organic frameworks have attracted much attention for electrocatalytic CO₂ reduction, but they are generally instable and difficult to control the product selectivity. We report flexible Cu(I) triazolate frameworks as efficient, stable, and tunable electrocatalysts for CO₂ reduction to C₂ H₄ /CH₄ . By changing the size of ligand side groups, the C₂ H₄ /CH₄ selectivity ratio can be gradually tuned and inversed from 11.8 : 1 to 1 : 2.6, giving C₂ H₄ , CH₄ , and hydrocarbon selectivities up to 51 %, 56 %, and 77 %, respectively. After long-term electrocatalysis, they can retain the structures/morphologies without formation of Cu-based inorganic species. Computational simulations showed that the coordination geometry of Cu(I) changed from triangular to tetrahedral to bind the reaction intermediates, and two adjacent Cu(I) cooperated for C-C coupling to form C₂ H₄ . Importantly, the ligand side groups controlled the catalyst flexibility by the steric hindrance mechanism, and the C₂ H₄ pathway is more sensitive than the CH₄ one.