N‐Heterocyclic Carbene‐Stabilized Ultrasmall Gold Nanoclusters in a Metal‐Organic Framework for Photocatalytic CO₂Reduction

Abstract

Ultrafine gold nanoclusters (Au‐NCs) are susceptible to migrate and aggregate, even in the porosity of many crystalline solids. N‐heterocyclic carbenes (NHCs) are a class of structurally diverse ligands for the stabilization of Au‐NCs in homogeneous chemistry, showing catalytic reactivity in CO2 activation. Herein, for the first time, we demonstrate a heterogeneous nucleation approach to stabilize ultrasmall and highly dispersed gold nanoclusters in an NHC‐functionalized porous matrix. The sizes of gold nanoclusters are tunable from 1.3 nm to 1.8 nm based on the interpenetration of the metal‐organic framework (MOF) topology. Control experiments using amine or imidazolium‐functionalized MOFs afforded the aggregation of Au species. The resultant Au‐NC@MOF composite exhibits a steady and excellent activity in photocatalytic CO2 reduction, superior to control mixtures without NHC‐ligand stabilization. Mechanistic studies reveal the synergistic catalytic effect of MOFs and Au‐NCs through the MOF‐NHC‐Au covalent‐bonding bridges.

Replacing Ru complex with carbon dots over MOF-derived Co3O4/In2O3 catalyst for efficient solar-driven CO2 reduction

“…1–3 The photocatalytic CO 2 reduction reaction suffers from poor activity and product selectivity, as a result of the complex multi-electron transfer path involved. 4–7 Considerable efforts have been made to enhance the photocatalytic CO 2 reduction activity, such as using photosensitizer and/or cocatalyst modification, 8 morphology engineering, 9 doping 10 and heterojunction construction. 11 Among these, the addition of photosensitizer, which can boost the charge transfer efficiency and provide more active sties to activate photocatalytic molecules, has, so far, been widely investigated.…”

Semiconducting MOF@ZnS Heterostructures for Photocatalytic Hydrogen Peroxide Production: Heterojunction Coverage Matters

“…[1][2][3][4][5][6][7][8] Similar to the problems in conventional inorganic photocatalysts (e.g., C 3 N 4 , TiO 2 ), [9,10] the rapid recombination of photogenerated electrons and holes in semiconducting MOFs has dramatically hindered their photocatalytic efficiency. [11][12][13][14][15][16][17][18][19] Construction of heterojunction by conjugating MOFs with other semiconductors with proper band gaps is a useful strategy to promote the separation of photogenerated electron-hole pairs. [15,17,[20][21][22][23][24][25] Among various reported conjugating semiconductors, [15,17,20,23] metal sulfides (MSs) with tunable bands and rich redox functions are widely applied to create MOFs@MSs heterostructures with reinforced photocatalytic performance.…”

Postsynthetic Modification of Metal−Organic Frameworks for Photocatalytic Applications

“…[53] The confinement effect significantly not only enhanced the lifetime of the excited electrons from photosensitizer molecules anchored on MOFs, but also shortened the transport distance of charge carriers from photoactive centers to active sites. [53] In conclusion, metal species incorporated into MOFs by PSM [33,64,70,87,212] contribute to adsorbing and activating CO 2 molecule due to the presence of the Lewis acidÀbase interaction, which reduces the thermodynamic barriers and accelerates the kinetics process of CO 2 reduction. The organic ligands provide an effective approach to regulate the bandgaps of MOFs, thus modulating the visible light response for photocatalytic CO 2 reduction.…”