Decoupled Solar Energy Storage and Dark Photocatalysis in a 3D Metal–Organic Framework

Abstract

Materials enabling solar energy conversion and long‐term storage for readily available electrical and chemical energy are key for off‐grid energy distribution. Herein, the specific confinement of a rhenium coordination complex in a metal–organic framework (MOF) unlocks a unique electron accumulating property under visible‐light irradiation. About 15 C gMOF−1 of electric charges can be concentrated and stored for over four weeks without loss. Decoupled, on‐demand discharge for electrochemical reactions and H2 evolution catalysis is shown and light‐driven recharging can be conducted for >10 cycles with ≈90% of the initial charging capacity retained. Experimental investigations and theoretical calculations link electron trapping to MOF‐induced geometry constraints as well as the coordination environment of the Re‐center, highlighting the key role of MOF confinement on molecular guests. This study serves as the seminal report on 3D porous colloids achieving photoaccumulation of long‐lived electrons, unlocking dark photocatalysis, and a path toward solar capacitor and solar battery systems.

Decoupled Artificial Photosynthesis

“…) under irradiation (Figure 5h). [50] Moreover, the composite after irradiation remained stable over 4 weeks. Such long-lived reductive equivalents, specifically, radical anions, allowed the delayed discharge for on-demand hydrogen evolution.…”

“…For instance, Lotsch et al demonstrated that highly reductive radicals with lifetimes longer than the diurnal cycle can be formed on a cyanamide-functionalized carbon nitride polymeric network under irradiation (Figure 5g). [48] Then, the trapped electrons were released for hydrogen production in the dark, thus [40] e) Ti-MIL-125-NH 2 with the formation of reductive Ti 3 + intermediate induced by the ligand-to-metal charge transfer (LMCT), [46] f) metal oxides with oxygen vacancies as the electron trapping sites, [47] Copyright 2022, Wiley-VCH GmbH, Weinheim, g) functionalized C x N y , [48] h) MOF confined Ru-bpy hybrids, [50] i) Cu-based metal complex that can store and release two electrons, [51] and j) POMs/Ru-bpy molecular dyad integrating the properties of photosensitizers and photocatalysts. [52] Copyright 2022, Nature Publishing Group.…”

“…d)-j) Typical decoupled photocatalytic systems that undergo light harvesting and charge transfer and separation processes under irradiation and produce chemicals or fuels in the dark. d) Conjugated organic polymer films (COPFs) bearing tautomer motifs and performing overall CO 2 splitting,[40] e) Ti-MIL-125-NH 2 with the formation of reductive Ti 3 + intermediate induced by the ligand-to-metal charge transfer (LMCT),[46] f) metal oxides with oxygen vacancies as the electron trapping sites,[47] Copyright 2022, Wiley-VCH GmbH, Weinheim, g) functionalized C x N y ,[48] h) MOF confined Ru-bpy hybrids,[50] i) Cu-based metal complex that can store and release two electrons,[51] and j) POMs/Ru-bpy molecular dyad integrating the properties of photosensitizers and photocatalysts [52]. Copyright 2022, Nature Publishing Group.…”

New Function of Metal–Organic Framework: Structurally Ordered Metal Promoter

“…A kind of Zr-based MOF (bpy-UiO) was utilized as carrier to incorporate Pd NPs and to chelate metal promotes for its high stability and abundant chelation sites in ligands (bpydc). [48][49][50] Pd NPs were selected as catalytically active sites for that Pdbased catalysts usually possess certain selectivity and high activity in NS hydrogenation. Pristine Pd/bpy-UiO catalyst was prepared by loading Pd NPs uniformly onto porous bpy-UiO Moreover, the diffuse reflectance ultraviolet-visible-near infrared (UV-vis-NIR) spectrum of Pd/bpy-UiO-Cu shows obvious metal-to-ligand charge transfer band at about 740 nm (Figure 2e), which suggests strong coordination between bpydc ligand and Cu promoters.…”

Photocatalytic CO2‐to‐Syngas Evolution with Molecular Catalyst Metal‐Organic Framework Nanozymes

“…[9][10][11] Here, porous colloids such as metal-organic frameworks (MOFs) offer unique benefits as their compositional modularity provides topologically versatile porous environments, adjustable chemical and optical properties, and high reaction surface areas. [12] In solar fuel production, various MOF-derived materials have been reported, [13][14][15] and specifically MOFs and molecular catalysts have been combined to modulate reaction environments, [16][17][18][19][20] enhance/control electron transfer, [21][22][23] or directly integrate biocatalysts. [24,25] All such composites, however, are practically constrained by framework stability in aqueous environments, moderate weight-based loading, limited light absorption mired with light scattering, and non-productive excited state quenching.…”