Search

H2O2 production by photocatalysis has received considerable attention, while using MOF‐based materials as photocatalysts is still less explored. Ligand functionalization of MOFs is a decoration way at the molecular level, which provides the basis for the further modification of MOFs. In this concept, ligand functionalization of MOFs for photocatalytic H2O2 production has been systematically and extensively discussed. The strategies of ligand functionalization include grafting of functional groups (e. g. amino, methoxyl, boron and alkyl) and multiple ligand decoration. Correspondingly, some specific effects are achieved, e. g. improved charge carrier separation, enhanced O2 adsorption and hydrophobicity, which can realize efficient H2O2 production by photocatalysis. Meanwhile, reaction conditions and activities of photocatalytic H2O2 production have also been explicitly introduced in these studies. At last, the future perspectives are proposed. This concept sheds fresh light on the great potential of ligand functionalization of MOFs for photocatalytic H2O2 production. [ABSTRACT FROM AUTHOR]

A series of covalent organic frameworks (COFs) with β‐ketoenamine linkages named TpTt‐COF, TAPT‐COF, and TpPa‐1 were constructed for photocatalytic H2O2 generation in pure water and ambient air under visible light. Among them, TpTt‐COF performed striking H2O2 yield of 2647 μmol L−1, which is 3.5, 17.5, and 176.5‐fold those of TAPT‐COF, TpPa‐1, and bulk g‐C3N4, respectively, attributing to the electron‐deficient trait, short charge diffusion distance, and the narrowest bandgap of TpTt‐COF. Additionally, to achieve the facile recovery, TpTt‐COF was firmly and evenly anchored on melamine sponges (MS) because plenty of amino groups on the surface of MS could be involved in the β‐ketoenamine formation and guide the synthesis of TpTt‐COF on MS. The corresponding H2O2 evolution over this photocatalyst monolith is also respectable and can be well repeated at least four times. This work is quite instructive for photocatalyst construction based on covalent organic frameworks and facile photocatalytic applications. [ABSTRACT FROM AUTHOR]

Porous triazine‐/heptazine‐based carbon nitride (THCN) homojunction with chloride (Cl) doping was synthesized by a simple, one‐step photochemical synthesis route for efficient visible‐light‐driven overall water splitting. The phase ratio of triazine‐based carbon nitride (TCN) and heptazine‐based carbon nitride (HCN), texture and morphology of the THCN isotype junction were finely tuned by varying ultraviolet irradiation time and washing solvents. After washing with acetonitrile, the resulting porous THCN nanosheets with 48 h irradiation contain 21 wt % TCN and 79 wt % HCN units and reveal a significantly improved photocatalytic performance with H2 and O2 production rates up to 7.9 and 4.2 μmol h−1, respectively, about 3.8 times higher than that of THCN prepared by 36 h illumination. The dual‐phase interaction, holey structure, and Cl dopants favor the exposure of active sites, extended visible‐light harvesting, accelerated charge transfer, and enhanced photoreduction ability, thereby improving photocatalytic activity. [ABSTRACT FROM AUTHOR]

Cellulose‐derived carbon (CC) dot‐directed growth of ZnIn2S4 was achieved through hydrothermal treatment of carboxylated cellulose followed by in situ growth of ZnIn2S4 nanosheets. The carbon dots inherited from carboxylated cellulose equip plenty of surface carboxyl groups, which induce the ionic interaction with Zn2+ and In3+ and the guided growth of ZnIn2S4. As a result, the nanosheets of ZnIn2S4 are evenly and intimately grown on the small carbon dots, providing high‐speed channels for charges transfer. In conjunction with the reinforced visible‐light capture and good conductivity of carbon dots, the resultant CC/ZnIn2S4 shows an outstanding photocatalytic activity. As a proof‐of‐concept, visible‐light‐driven 5‐hydroxymethylfurfural oxidation into 2,5‐diformylfuran was conducted. The evolution of 2,5‐diformylfuran over the optimal CC/ZnIn2S4 sample can reach ∼2980 μmol g−1, about 3.4 times that of pristine ZnIn2S4. Additionally, the apparent quantum yield could attain 3.4 % at a wavelength of 400 nm. [ABSTRACT FROM AUTHOR]

Abstract: Selectivity of cascade redox reactions: the reduction of nitrobenzene to azoxybenzene and then to azobenzene and the oxidation of benzyl alcohol to benzaldehyde and then to benzoic acid, is discovered to be tuneable via light irradiation over plasmonic gold photocatalysts. The representative photocatalyst of Au/CeO2 was characterized by TEM, EDX, UV-Vis and XPS to determine its morphology, elemental composition, photo absorptivity and oxidation state of gold. The catalytic test results demonstrate that the net contribution of light irradiation correlates with the ability of incident light to excite electrons and light absorption of catalysts. These findings may inspire peer researchers in developing new photocatalytic processes or in designing new photocatalysts for clean chemicals synthesis.Graphical Abstract: [ABSTRACT FROM AUTHOR]

[Display omitted] • The whole advancement of MOF-based photocatalysts for H 2 O 2 production was discussed. • Diverse tailoring strategies on MOFs for H 2 O 2 production were summarized in detail. • H 2 O 2 production pathways, activities and reaction conditions were elucidated. • Outlooks on current challenges and emerging opportunities were presented. Photocatalytic synthesis of H 2 O 2 is currently in the spotlight because of its green and sustainable nature, but the construction of photocatalysts with high efficiency is still the key. In this regard, emerging photocatalysts based on metal–organic frameworks (MOFs) have been revitalized for the green synthesis of H 2 O 2 with the various acclaimed merits of MOFs. Therefore, this review provides an insight into the overall progress of MOF-based photocatalysts for H 2 O 2 production through various modification strategies on MOFs, including molecular-level decoration (ligand and metal center decoration, defect and facet engineering), heterostructure construction (C 3 N 4 /MOFs, metal sulfides/MOFs and metal oxides/MOFs) and derivatization (metal oxides/sulfides and carbonaceous materials). Meanwhile, the corresponding pathways (oxygen reduction reaction and water oxidation reaction), performances and reaction conditions for photocatalytic H 2 O 2 production were elucidated. Finally, outlooks on current challenges and emerging opportunities in this research field were presented. We hope this review will inspire and contribute to the future development of both MOF-based catalysts and H 2 O 2 green production. [ABSTRACT FROM AUTHOR]

Abstract In this study, homogeneous alloy Au Pt nanoparticles were successfully immobilized on ultrathin TiO 2 nanorods via a facile photodeposition technique. The Au Pt/TiO 2 hybrid exhibited high photocatalytic activity and stability during the selective photosynthesis of benzaldehyde from benzyl alcohol under visible light. The optimal performance was obtained with the Au 1 Pt 1 /TiO 2 sample, which had a benzyl alcohol conversion rate of 65.3%. The engineered TiO 2 nanorods (304 m2/g) can be employed as a stabilizing matrix and an excellent dispersant for noble metal particles. Moreover, the formation of the alloy structure substantially enhances the photoinduced carrier separation efficiency compared with loading Au or Pt alone on TiO 2. The bimetallic nanoparticles exhibited the properties related to the individual metals, as well as new properties due to synergistic effects of the electron-accumulating function of Pt and the surface plasmon resonance of Au. Graphical abstract Image 1 Highlights • Au Pt alloy successfully immobilized on ultrathin TiO 2 nanorods. • Au Pt/TiO 2 exhibited enhanced photocatalytic performance and good stability. • Benzyl alcohol conversion rate was 65.3% in the presence of Au 1 Pt 1 /TiO 2. [ABSTRACT FROM AUTHOR]

The delicate design of photocatalyst monoliths is of great significance for the practical applications of artificial photocatalysis. An in-situ synthesis to prepare ZnIn 2 S 4 /cellulose foam was developed. Cellulose is dispersed in a highly concentrated ZnCl 2 aqueous solution to prepare Zn2+/cellulose foam. Zn2+ ions are pre-anchored by hydrogen bonds on cellulose and become in-situ sites for synthesizing ultra-thin ZnIn 2 S 4 nanosheets. This synthesis method makes ZnIn 2 S 4 nanosheets and cellulose tightly bound and prevents ZnIn 2 S 4 nanosheets from stacking in multiple layers. As a proof of concept, the prepared ZnIn 2 S 4 /cellulose foam exhibits a favorable performance for photocatalytic reduction of Cr(VI) under visible light. By adjusting the concentration of zinc ions, the optimal ZnIn 2 S 4 /cellulose foam is capable to completely reduce Cr(VI) in 2 h and the photocatalytic activities show no decrease after 4 cycles. This work could inspire people to build floating cellulose-based photocatalysts via in-situ synthesis. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Core-shell Bi-MOF@BiOX is fabricated by a one-pot solvothermal strategy. • The competitive coordination effect to Bi3+ makes BiOX and Bi-MOF contact closely. • Bi-MOF@BiOX has nice activities on Cr(VI), tetracycline and o-nitrophenol removal. • For above reactions, more than 13, 7, 5-time enhancements of activity are achieved. • Enhanced activities are observed for the treatment of mixed pollutants. Core-shell Bi-MOF@BiOX (X = I, Br and Cl) hybrids were fabricated by a one-pot solvothermal strategy via regulating the concentration and type of halogen ions in the Bi-based CAU-17 synthesis. By virtue of the competitive coordination effect to Bi3+ between CAU-17 and BiOX, CAU-17 was converted into another Bi-MOF with similar structures and compositions. Moreover, Bi3+ plays the role of "bridge" and endows an intimate interface contact between BiOX and the Bi-MOF, which immensely expedites the charge and mass transportation. The obtained Bi-MOF@BiOX hierarchical heterostructures were applied to photocatalytic elimination of solo and mixed pollutants (Cr(VI)/tetracycline and Cr(VI)/o-nitrophenol), and exhibited favorable performances. Choosing Bi-MOF@BiOI as a typical example, the corresponding performances for Cr(VI) reduction, tetracycline and o-nitrophenol degradation in their solo systems are 14, 10, 8 times higher than those of CAU-17, and 13, 7, 5 times higher than those of BiOI under visible light, respectively. Of note, the above photocatalytic performances could be further improved in the coexisting environment of Cr(VI) and tetracycline or o-nitrophenol, which is attributed to the elevated charge separation efficiency caused by the timely consumption of photo-excited electrons and holes. This work gives some insights into the delicate design of MOF photocatalysts and their applications in environmental restoration. [ABSTRACT FROM AUTHOR]

A novel and highly efficient photocatalyst of Cd 0.5 Zn 0.5 S@ZIF-8 nanocomposite has been developed by a facile self-assembly strategy. This is the first report on the application of Cd x Zn 1−x S and metal-organic framework (MOF) nanocomposite as photocatalysts for the reduction of Cr(VI). The resulting Cd 0.5 Zn 0.5 S@ZIF-8 exhibited higher photocatalytic activity than that of pristine Cd 0.5 Zn 0.5 S and ZIF-8. Particularly, the CZS@Z60 composite with 60 wt% of ZIF-8 exhibited a photocatalytic activity that is about 1.6 times as high as that of Cd 0.5 Zn 0.5 S. The dominant reason for the improved photocatalytic reduction potential is proved to be the newly-formed interfacial S Zn bonds that firmly connect Cd 0.5 Zn 0.5 S and ZIF-8 and substantially improve the separation efficiency of photo-excited electrons and holes. The newly-formed chemical bonds are confirmed by XPS analyses, and the prolonged lifetime of photo-excited electrons is evidenced by the electrochemical measurement of photocurrent, which shows that the photocurrent on Cd 0.5 Zn 0.5 S@ZIF-8 is much higher than that of Cd 0.5 Zn 0.5 S and ZIF-8. This study clearly demonstrates that the MOF-based composite nanomaterials hold great promises for applications in the field of environmental remediation and for design of novel photocatalytic materials. [ABSTRACT FROM AUTHOR]

The reduced graphene oxide (RGO) loaded Zn 0.5 Cd 0.5 S nanocomposite has been successfully prepared by a facile solvothermal method. The as-prepared photocatalysts were characterized by a combination of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and N 2 absorption-desorption. The Zn 0.5 Cd 0.5 S@RGO composites with a RGO content of 0.5 wt% (GS-0.5) showed the highest photocatalytic activity for the degradation of various dyes (methylene blue, methyl orange and Rhodamine B), which is mainly due to the uniform dispersion of nanoparticles on RGO sheets and the enhanced separation rate of photo-induced electrons and holes. The GS-0.5 photocatalyst can be repetitively used without significant loss of activity. This new material holds great promise for applications in the field of water purification as well as optoelectronic fields at a large scale. [ABSTRACT FROM AUTHOR]

N-doped titania is prepared using ethylenediamine as the nitrogen source by a sol–gel method. The preparation conditions, such as the volume ratio of ethylenediamine to sol, and the heat temperature on the nitrogen doping are systematically examined. UV results indicate the N-doped TiO 2 catalysts have enhanced absorption in the visible light region, and exhibit high activities on the visible light photocatalytic reactions to the hydrogen production and methyl orange degradation. X-ray diffraction (XRD) and FT-IR results reveal that N species have been incorporated into the TiO 2 lattice at a high N-doping level. N-doped titania prepared with an ethylenediamine to sol volume ratio of 1:1 and sintering temperature of 500 °C performed the highest hydrogen production rate (2.98 mmol g −1 h −1 ) and best methyl orange degradation performance. A conceivable structure change of N-doped TiO 2 sintered at different temperature was proposed. [ABSTRACT FROM AUTHOR]

MIL-101(Cr)@ZnIn 2 S 4 hierarchical heterojunction was delicately designed and fabricated through the in-situ growth of ZnIn 2 S 4 on MIL-101 and electrostatic self-assembly. It is affirmed that the Cr–S interface bonding between MIL-101 and ZnIn 2 S 4 in their composite was established based on the characterization results of X-ray photoelectron spectroscopy, Raman and zeta potential. Thus, a high-speed channel for charges transfer is offered due to the Cr–S bond, intimate interface contact and hierarchical structure of MIL-101@ZnIn 2 S 4 , which largely inhibits the recombination of photo-induced charge carriers and promises a remarkable photocatalytic activity. Choosing visible-light-driven reduction of Cr(VI) as a model, the optimal MIL-101@ZnIn 2 S 4 sample can reduce 95% of Cr(VI) within 30 min, corresponding to a rate constant of 0.107 min−1, which is 2.9-fold compared with blank ZnIn 2 S 4 counterpart (MIL-101 has a negligible performance). Additionally, a conspicuous apparent quantum yield of 9.7% can be achieved at a wavelength of 420 nm. Eventually, to reinforce the practicability of MIL-101@ZnIn 2 S 4 , the composite powders were manufactured as aerogels utilizing bacterial cellulose as a substrate. The MIL-101@ZnIn 2 S 4 aerogel still exerts an enviable performance for photocatalytic reduction of Cr(VI) and stability. This work could inspire the material design and environmental remediation based on MOFs. [Display omitted] • MIL-101@ZnIn 2 S 4 hierarchical heterojunction with Cr–S bonds was delicately designed. • A high-speed channel for charges transfer is presented over MIL-101@ZnIn 2 S 4. • Efficiently photocatalytic reduction of Cr(VI) is achieved over MIL-101@ZnIn 2 S 4. • Aerogel was prepared from powder to improve the practicability of MIL-101@ZnIn 2 S 4. [ABSTRACT FROM AUTHOR]

In recent years, organic-inorganic composites have aroused considerable attention due to their tunable properties, where cellulose tailored semiconductors for artificial photocatalysis are typical examples. In virtue of the unique fibrous structure and abundant surface functional groups, cellulose employed in the design of photocatalysts could endow good hydrophilicity, dispersity, stability, high porosity, conductivity, large surface area and even unexpected morphologies. In this review, the modification strategies of cellulose to semiconductors (function as assistants and sacrifice as bio-templates), diverse monoliths (films, gels and textiles) and their photocatalytic applications (contaminants treatment and H 2 production) are summarized in detail. In addition, the challenges and outlook of semiconductor/cellulose photocatalysts are also discussed. • Cellulose tailored semiconductors for photocatalysis were summarized in detail. • Two strategies including cellulose as assistant and bio-template were introduced. • Diverse semiconductor/cellulose photocatalyst monoliths were depicted. • Various photocatalytic applications over semiconductors/cellulose were described. [ABSTRACT FROM AUTHOR]

Highlights: [•] Preparation of aliphatic pinacol for the first time in an aqueous solution at room temperature. [•] Photocatalytic C C coupling reaction using isopropanol as the starting material. [•] Phase and pore structure modulation of commercial TiO2 by calcination. [Copyright &y& Elsevier]

• BiOI/MIL-121 photocatalyst is constructed by a facile hydrothermal method. • BiOI/MIL-121 performs excellently for tetracycline degradation under visible light. • Free carboxyl in BiOI/MIL-121 can adsorb tetracycline through hydrogen bond. A series of BiOI/MIL-121(Al) hybrid photocatalysts has been prepared by a facile hydrothermal method. Two-dimensional BiOI sheets are intimately anchored on rod-like MIL-121 due to the electrostatic and coordination effects between Bi3+ and carboxyl. The BiOI/MIL-121(Al) hybrid exhibits favorable performances for visible-light-driven degradation of tetracycline. The degradation performance of the optimal sample BM-20 is more than twice as that of pure BiOI. Apart from the close contacts between BiOI and MIL-121, the hydrogen bond induced by carboxyl in MIL-121 promotes the adsorption of tetracycline, which is also conducive to the photocatalytic degradation process. Moreover, results show that photo-induced holes and superoxide radicals are both the main active species for the photocatalytic degradation of tetracycline over BiOI/MIL-121 composites. This work would inspire the materials design with specific functional groups for efficient (photo)catalytic reaction. [ABSTRACT FROM AUTHOR]

• Cd x Zn 1-x S/ZnO nanocomposites were readily fabricated via a facile one-pot method. • The Cd/Zn molar ratios were tuned by altering the amounts of Na 2 S and Na 2 S 2 O 3. • Cd x Zn 1-x S/ZnO showed glorious performance on photocatalytic reduction of Cr(VI). • Cd 0.68 Zn 0.32 S/ZnO nanoparticles have tiny diameters of about 5−8 nm. Cd x Zn 1-x S/ZnO nanohybrids were fabricated by using mixed Na 2 S and Na 2 S 2 O 3 as the sulfur source via a facile one-pot synthesis. Cd x Zn 1-x S/ZnO with x = 0.54, 0.58, 0.62, 0.68 and 0.75 was successfully tuned by altering the molar ratio of Na 2 S and Na 2 S 2 O 3. Sole sulfur source Na 2 S or Na 2 S 2 O 3 could only generate Cd 0.5 Zn 0.5 S or CdS/ZnO, respectively. The in-situ co-growth of Cd x Zn 1-x S and ZnO makes them combine penetratingly in Cd x Zn 1-x S/ZnO nanohybrids, giving them a highly intimate contact. The natural matched band-edge positions and highly intimate contacts between Cd x Zn 1-x S and ZnO are conductive to charge separation and transfer. Benefiting from the structural and compositional merits, the optimized Cd x Zn 1-x S/ZnO nanohybrid with sizes of about 5−8 nm exhibited outstanding performance for Cr(VI) reduction under visible-light illumination. The newly designed one-pot synthetic strategy in this work may provide a brand-new pathway in developing high-efficiency multi-component photocatalysts for practical use. [ABSTRACT FROM AUTHOR]