Selective CO₂-to-Formate Conversion Driven by Visible Light over a Precious-Metal-Free Nonporous Coordination Polymer

Abstract

Metal−organic frameworks (MOFs) and coordination polymers (CPs) are potential candidates for high-performance photocatalysts because of their high tunability of electronic and structural properties. For example, MOFs and CPs having a high specific surface area (∼1000 m 2 g −1 ) have been applied as visible-light-driven photocatalysts for CO 2 reduction and water splitting. Herein, we show a unique CP possessing a metal−sulfur bond with Pb 2+ , an earth-abundant metal ion. Different from ordinary high-surface-area MOFs and CPs, this CP is nonporous and has just 0.7 m 2 g −1 surface area. Nevertheless, owing to its capability of absorbing visible light up to ∼500 nm, it efficiently photocatalyzes CO 2 reduction to formate (HCOO − ) under visiblelight irradiation with >99% selectivity and an apparent quantum yield of 2.6% at 400 nm, even without postmodification treatment such as cocatalyst loading. These values are the highest yet reported for a precious-metal-free single-component photocatalyst for the visible-light-driven reduction of CO 2 to HCOO − . This work may thus shed light on the great potential of nonporous CPs as building units of photocatalytic CO 2 conversion systems.

Robust {Cd4}-Organic Framework for Efficiently Catalyzing CO2 Cycloaddition and Knoevenagel Condensation

“…Currently, there have been numerous reports on transforming CO 2 into high-value-added products, mainly in the fields of photochemical products, fine chemical products, and polymeric materials. − Among the many chemicals prepared from CO 2 , the preparation of cyclic carbonates is one of the most promising ways to achieve industrial application prospects for the utilization of CO 2 . Due to the advantages of high boiling point, large polarity, stable properties, safety, and nontoxicity, cyclic carbonates have very wide applications, such as intermediates of fine chemical products, polar aprotic solvents, lithium-ion battery electrolytes, and so on. − To date, many heterogeneous and homogeneous catalysts have successfully been applied to the synthesis of cyclic carbonates, mainly including common organic small molecules (ionic liquids, organic bases, etc. ), metal oxides or salts, MOFs, COFs, and so on .…”

Metal–Organic Framework Catalysts for Solar Fuels: Light-Driven Conversion of Carbon Dioxide into Formic Acid

“…Tanaka, Maeda and co-workers reported the CO 2 photoreduction using nonporous coordination polymer (CP) made with Pb 2+ cations linked by 1,3,4-thiadiazole-2,5-dithiol, named KGF-9, and containing a (−Pb−S−) n infinite structure. 39 KGF-9 presented a very small surface area of 0.7 m 2 /g. Using a solution of 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH) in dimethyl sulfoxide (DMSO) under 370− 500 nm light irradiation, KGF-9 allowed reaching a HCOOH productivity of 1.15 mmol HCOOH /g cat /h.…”

“…Tanaka, Maeda and co-workers reported the CO 2 photoreduction using nonporous coordination polymer (CP) made with Pb 2+ cations linked by 1,3,4-thiadiazole-2,5-dithiol, named KGF-9, and containing a (−Pb–S−) n infinite structure . KGF-9 presented a very small surface area of 0.7 m 2 /g.…”

Tin(II)‐Based Metal–Organic Frameworks Enabling Efficient, Selective Reduction of CO2 to Formate under Visible Light

“…Notably, in the present KGF‐10 CO 2 photoreduction system, the AQY value reached 9.8 % at 400 nm. We have recently reported that another MOF‐type material possessing a Pb−S bond (called KGF‐9) can reduce CO 2 to HCOO − with an AQY of 2.6 % at 400 nm, [13b] which was the highest AQY reported for a precious‐metal‐free single component photocatalyst towards CO 2 conversion into HCOO − . In the present work, better performance (9.8 % AQY) was obtained using Earth‐abundant Sn II ‐based MOFs that do not contain toxic Pb.…”