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Al-MIL-101-NH2, which was previously regarded as being inactive as a photocatalyst, produces hydrogen peroxide (H2O2) via O2 reduction under visible-light irradiation, accompanied by efficient suppression of undesired H2O2 decomposition. The low-coordination Lewis acid sites in trimetric Al-oxo clusters are crucial for the electron transfer to O2. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) water splitting is a promising approach to convert inexhaustible solar energy to hydrogen energy. In this system, the semiconductor is a crucial part as photoelectrode to harvest the solar light and achieve water splitting on the surface. For the surface modification of semiconductor, cocatalyst loading is an effective method to improve the sluggish reaction kinetics. Due to the specific structure of their organic ligands, the metal‐organic frameworks (MOFs) or molecular catalysts as cocatalysts can provide more reaction sites and overcome the interface recombination between semiconductors and cocatalyst layers. The inorganic metal species derived from the MOFs or molecular catalysts also possess porous structures. This review summarizes the recent developments of MOFs and molecular catalysts as well as their derivatives modifying several representative semiconductors for PEC water oxidation reaction. The synthesis methods and performance enhancements are discussed. Finally, this review addresses remarks on current existing changes and perspectives for the further development. [ABSTRACT FROM AUTHOR]

Much effort has been devoted to photocatalytic production of hydrogen peroxide (H2O2) as an alternative to fossil fuels. From an economic point of view, reductive synthesis of H2O2 from O2 coupled with the oxidative synthesis of value‐added products is particularly interesting. We herein report application of MIL‐125‐NH2, a photoactive metal–organic framework (MOF), to a benzylalcohol/water two‐phase system that realized photocatalytic production and spontaneous separation of H2O2 and benzaldehyde. Hydrophobization of the MOF enabled its separation from the aqueous phase. This resulted in enhanced photocatalytic efficiency and enabled application of various aqueous solutions including extremely low pH solution which is favorable for H2O2 production but fatal to MOF structure. In addition, a highly concentrated H2O2 solution was obtained by simply reducing the volume of the aqueous phase. In the right phase: Hydrogen peroxide (H2O2) is produced in a two‐phase water/benzylalcohol system which contains MIL‐125‐NH2, a Ti‐containing metal–organic framework (MOF) as the photocatalyst. Two products of the catalysis, H2O2 and benzaldehyde, spontaneously separated into the two phases. Hydrophobized MOF dispersed to the organic phase, which enhanced activity and also made it possible to apply various harsh aqueous phases in the photocatalysis. [ABSTRACT FROM AUTHOR]

Abstract: Single‐site photocatalysts generally display excellent photocatalytic activity and considerably high stability compared with homogeneous catalytic systems. A rational structural design of single‐site photocatalysts with isolated, uniform, and spatially separated active sites in a given solid is of prime importance to achieve high photocatalytic activity. Intense attention has been focused on the design and fabrication of single‐site photocatalysts by using porous materials as a platform. Metal–organic frameworks (MOFs) have great potential in the design and fabrication of single‐site photocatalysts due to their remarkable porosity, ultrahigh surface area, extraordinary tailorability, and significant diversity. MOFs can provide an abundant number of binding sites to anchor active sites, which results in a significant enhancement in photocatalytic performance. In this focus review, the development of single‐site MOF photocatalysts that perform important and challenging chemical redox reactions, such as photocatalytic H2 production, photocatalytic CO2 conversion, and organic transformations, is summarized thoroughly. Successful strategies for the construction of single‐site MOF photocatalysts are summarized and major challenges in their practical applications are noted. [ABSTRACT FROM AUTHOR]

Liquid-phase oxidation of alkylaromatics with molecular O2 was examined using a microporous Mn-based metal–organic framework (Mn-MOF-74). Mn-MOF-74 consisting of trimeric Mn clusters and 2,5-dihydroxyterephthalate (dhtp) linkers exhibits superior catalytic activity with good ketone selectivity compared to conventional oxide-supported Mn catalysts without showing any lengthy induction period. Combined analyses by means of XRD, FE-SEM, N2 physisorption and Mn K-edge XAFS reveal that the superior catalytic performance is attributed to the inherently-formed Mn(iii)2(dhtp) moieties embedded in the Mn-MOF-74 framework rather than structural factors associated with the MOF. The catalyst is reusable over multiple catalytic runs along with retaining its original catalytic activity due to the ability of the dhtp ligand to stabilize active Mn(iii) atoms. Owing to high activity, reusability and nontoxicity, Mn-MOF-74 can offer a simple, inexpensive and efficient protocol for the oxidation of some important alkylaromatics, such as ethylbenzene and diphenylmethane to produce the corresponding aromatic ketones. [ABSTRACT FROM AUTHOR]

In this study, monometallic gold and palladium, and bimetallic gold/palladium were respectively deposited on chromium based amine-functionalized metal-organic framework (NH-MIL-101) by using the impregnation method, with the aim to enhance the activity of Pd-catalyzed chemical reaction under the assistance of visible light at ambient temperatures. The oxidation state, size and location of metal nanoparticles were determined by XAFS and TEM. The physical properties of as-synthesized catalysts were also well characterized by UV-vis spectroscopy, BET and XRD. The catalytic activities of those metal nanoparticles deposited MOFs were studies for hydrolysis of ammonia borane and Suzuki-Miyaura coupling reaction. Compared with monometallic counterpart, the bimetallic gold/palladium showed much higher catalytic activity for hydrolysis of ammonia borane and Suzuki-Miyaura coupling reaction under visible light irradiation. The enhancement of the catalytic activity might be attributed to the synergistic effect between plasmonic bimetallic nanoparticles and metal organic framework in effective conversion of solar energy for generating electron rich palladium species to activate the electrophilic compounds as well as nucleophilic partner compounds. This investigation offers a new opportunity to explore the high-performance metal nanoparticle loaded MOFs photocatalysts for efficient utilization of sunlight in a wide range of chemical reactions. [ABSTRACT FROM AUTHOR]

MOFs offers a potential platform for anchoring photosensitizers and catalytic moieties, encapsulating metal nanoparticles, and supporting the semiconductor to drive chemical H 2 production reactions by taking the advantages of large surface area, permanent pores and tunable channels as well as tailorable physical and chemical functions. Recently, considerable attention has been paid to the application of MOFs in heterogeneous photocatalysis for H 2 production. In this review, the latest progress of MOFs involved in the reaction of H 2 production from water and visible-light-enhanced H 2 releasing from hydrogen carriers were summarized. The successful methods to maximize photocatalytic activity of H 2 production from water by introducing light sensitization and anchoring catalytic sites within MOFs, tuning the band gap of MOFs by modification of functional groups were also highlighted. Also the latest advances in heterogeneous organic dye-sensitized metal nanoparticle supported on MOFs for photocatalytic H 2 production and visible light enhanced H 2 production from H 2 carriers were emphasize. In the end, a brief perspective to the challenges and new development directions in the development of highly active MOFs to achieve high photocatalytic activity in the H 2 production is also discussed, which would be of great interest in the solar energy conversion. [ABSTRACT FROM AUTHOR]