Photochemical Reduction of Low Concentrations of CO₂ in a Porous Coordination Polymer with a Ruthenium(II)–CO Complex

Abstract

Direct use of low pressures of CO 2 as aC 1s ource without concentration from gas mixtures is of great interest from an energy-saving viewpoint. Porous heterogeneous catalysts containing both adsorption and catalytically active sites are promising candidates for such applications.H ere,w e report ap orous coordination polymer (PCP)-based catalyst, PCP-Ru II composite,b earing aR u II -CO complex active for CO 2 reduction. The PCP-Ru II composite showed improved CO 2 adsorption behavior at ambient temperature.I nt he photochemical reduction of CO 2 the PCP-Ru II composite produced CO,H COOH, and H 2 .C atalytic activity was comparable with the corresponding homogeneous Ru II catalyst and ranks among the highest of knownP CP-based catalysts. Furthermore,c atalytic activity was maintained even under a5 %C O 2 /Ar gas mixture,r evealing as ynergistic effect between the adsorption and catalytically active sites within the PCP-Ru II composite.Use of CO 2 as aC 1s ource is an important contemporary research topic for various reasons,s uch as reducing CO 2 emissions and developing an alternative energy feedstock for fossil fuels.T ransformations of CO 2 into organic chemicals have been studied extensively.[1] Among these processes,CO 2 reduction (hydrogenation) is of particular interest because the products (for example CO,H COOH, MeOH, and CH 4 ) are regarded as energy carriers and are key materials in C1 chemistry.A lthough several homogeneous and heterogeneous catalysts with high efficiency have been developed for such reactions,t hey usually require high temperature and/or high CO 2 pressures, [1,2] which is unfavorable from both energetic and economic viewpoints.I nt his context, direct use of low partial pressures of CO 2 without concentration from gas mixtures,s uch as flue gas (5-15 %C O 2 )a nd air (400 ppm CO 2 ), [2] are interesting from an energy-saving perspective.Porous heterogeneous catalysts containing both adsorption and catalytically active sites are promising candidates for catalyzed CO 2 transformations.P orous coordination polymers (PCPs), also known as metal-organic frameworks (MOFs), [3] are anew class of porous heterogeneous catalysts with highly tailorable characteristics.[4] Several research groups have reported PCP-based catalysts for CO 2 reduction, [5][6][7][8] with ac haracteristic focus upon the stability of heterogeneous catalysts over extended periods,o rt heir recyclability.A lthough CO 2 capture and separation have been actively investigated within the PCP research field [9] the adsorption properties of these materials have not been adequately correlated with their catalytic properties. Herein, we report an ew PCP-based catalyst with aR u II -CO complex, [Ru II (bpy)(terpy)(CO)](PF 6 ) 2 (1;b py = 2,2'-bipyridine,t erpy = 2,2':6',2''-terpyridine;S upporting Information, Scheme S2), [10] incorporated in the form of am etallolinker. After integrating the CO 2 reducing catalyst 1 into aC O 2 -adsorptive PCP,t he resulting PCP-Ru II composite produced CO and HCOOH with high turnov...

Metal‐Organic Frameworks for CO2 Chemical Transformations

“…At this time, heterogeneous MOF photocatalysts have been achieved by introducing photoactive catalytic sites (e.g., metal ions or metallolinkers) in MOF materials . Lin and co‐workers incorporated Re(bpydc)(CO) 3 Cl complexes into UiO‐67 to achieve a photocatalytic MOF for CO 2 reduction to carbon monoxide (CO) using a mix‐and‐match synthetic strategy .…”

“…Motivated by the above example, intensive research efforts have been made to explore and synthesize such heterogeneous MOF photocatalysts for visible‐light‐driven CO 2 reduction. Kajiwara and co‐workers introduced molecular catalyst (Ru 2+ (H 2 bpydc)(terpy)(CO))(PF 6 ) 2 or H 2 RuCO complex (ligand modified from (Ru 2+ (bpy)(terpy)(CO))(PF 6 ) 2 or Ru 2+ ‐CO) via post‐synthetic exchange into the UiO‐67 framework forming Zr‐bpdc/RuCO photocatalyst ( Figure a) . The resulting material exhibited high catalytic activity for CO 2 photoreduction to CO, HCOOH and H 2 .…”

“…b) Photochemical reduction of CO 2 with H 2 RuCO and Zr‐bpdc/RuCO: left γ‐axis, catalytic activity (bar graph); right γ‐axis, product selectivity (line graph). Reproduced with permission . Copyright 2016, Wiley‐VCH.…”

Facile electron delivery from graphene template to ultrathin metal-organic layers for boosting CO2 photoreduction

“…To address these issues, metal-organic frameworks (MOFs), bene ting from their porous feature, ordered structure and molecular tunability, have been widely used to mediate photocatalytic CO 2 reduction. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In this eld, Lin et al, 16 incorporated Re(CO) 3 (bpy)Cl (bpy = bipyridine) modules into the UiO-67 framework, achieving a total turnover number (TON) of 10.9 in photocatalytic CO 2 -to-CO conversion. Wang et al achieved a high TON of 450 by using a Co-based zeolitic imidazolate framework as the cocatalyst in the presence of [Ru(bpy) 3 ] 2+ photosensitizer (PS).…”

Incorporation of Functional Groups Expands the Applications of UiO‐67 for Adsorption, Catalysis and Thiols Detection

“…It was also reported that RuDCBPY‐doped UiO‐67 could be grown onto the glass substrates coated with the conductive fluorine‐doped tin oxide (FTO) without changing the excited state properties of the material . Before long, RuDCBPY‐doped UiO‐67 films were studied to grow onto TiO 2 and in order to generate a sensitizing material for photovoltaic solar cell applications in the report of Maza et al . The synthetic MOFs sensitized solar cells could generate a moderate photocurrent in response to the 1 sun illumination which was simulated.…”