Search

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]

A hydrophobic MOF, OPA/MIL-125-NH2, whose Ti cluster was alkylated with octadecylphosphonic acid (OPA), was found to enhance photocatalytic H2O2 production in a two-phase system. Its activity exceeded that of linker-alkylated MIL-125-NH2. OPA/MIL-125-NH2 was modified on its outermost surface, which resulted in the activity enhancement while preserving the inner pores of the inherent MOF. [ABSTRACT FROM AUTHOR]

Pd nanoparticles (NPs) supported on Ti-doped graphitic carbon nitride (g-C3N4) were synthesized by a deposition-precipitation route and a subsequent reduction with NaBH4. The features of the NPs were studied by XRD, TEM, FTIR, XPS, EXAFS and N2-physisorption measurements. It was found that the NPs had an average size of 2.9 nm and presented a high dispersion on the surface of Ti-doped g-C3N4. Compared to Pd loaded on pristine g-C3N4, the Pd NPs supported on Ti-doped g-C3N4 exhibited a high catalytic activity in formic acid dehydrogenation in water at room temperature. The enhanced activity could be attributed to the small Pd NPs size, as well as the strong interaction between Pd NPs and Ti-doped g-C3N4. [ABSTRACT FROM AUTHOR]

A straightforward aqueous synthesis of MoO3− x nanoparticles at room temperature was developed by using (NH4)6Mo7O24⋅4 H2O and MoCl5 as precursors in the absence of reductants, inert gas, and organic solvents. SEM and TEM images indicate the as-prepared products are nanoparticles with diameters of 90-180 nm. The diffuse reflectance UV-visible-near-IR spectra of the samples indicate localized surface plasmon resonance (LSPR) properties generated by the introduction of oxygen vacancies. Owing to its strong plasmonic absorption in the visible-light and near-infrared region, such nanostructures exhibit an enhancement of activity toward visible-light catalytic hydrogen generation. MoO3− x nanoparticles synthesized with a molar ratio of MoVI/MoV 1:1 show the highest yield of H2 evolution. The cycling catalytic performance has been investigated to indicate the structural and chemical stability of the as-prepared plasmonic MoO3− x nanoparticles, which reveals its potential application in visible-light catalytic hydrogen production. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H 2 O 2) has attracted considerable interest due to its status as an eco-friendly oxidant and a sustainable energy carrier. This review summarizes current advancements in various photocatalysts, including metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), titanium dioxide (TiO 2), ionic carbon nitride, quantum dots (QDs), coordination polymer (CP), and heterojunction materials, applied for H 2 O 2 production in several types of two-phase systems, composed of benzyl alcohol (BA), toluene or octanol organic phase and water phase. Such two-phase media enables spontaneous separation of the produced reduction product (H 2 O 2) from oxidation product, benzaldehyde (BAL) or octanal and photocatalysts suppressing H 2 O 2 decomposition. The goal of the present review is to provide more fresh perspective on the future developments in the field of sustainable H 2 O 2 production in two-phase system. [Display omitted] • Two-phase systems with organic and water phases were used in H 2 O 2 photo-synthesis. • The biphasic system inhibits H 2 O 2 decomposition via separating H 2 O 2 from catalysts. • Different methods of hydrophobic modification on diverse materials were summarized. • Autocatalysis of benzyl alcohol/benzaldehyde shows little impact on this system. [ABSTRACT FROM AUTHOR]

• Lanthanum Strontium Cobalt (LSC) perovskites were prepared by sol-gel method. • Doped-LSC perovskites were assessed in ammonia borane decomposition. • The closer interaction Cu-Co might be favoring the catalytic activity. • Cu doping was found to be a good option to boost the catalytic activity. Lanthanum Strontium Cobalt (LSC) perovskite-based catalysts were prepared and evaluated in the ammonia borane dehydrogenation reaction. Doping with additional non-noble metals, such as Ni or Cu greatly enhanced the catalytic performance, especially in the case of Cu. In order to evaluate the effect of the Cu loading, catalysts with various Cu contents ranging from 0.82 to 5.42 wt.% were synthesized. It was found that the Cu-doped sample with a nominal formula of La 0.7 Sr 0.3 Co 0.90 Cu 0.10 O 3 containing 2.72 wt.% of Cu displayed the highest catalytic activity among investigated, which outperformed the counterpart Cu-supported catalyst (Cu/La 0.7 Sr 0.3 CoO 3). La 0.7 Sr 0.3 Co 0.90 Cu 0.10 O 3 showed good durability during five consecutive reaction runs, confirming the suitability of perovskite-type catalysts in stabilizing the catalytic active phase. The present catalytic system provides a cost-effective alternative to the noble-metal-based catalysts commonly used to catalyze the ammonia borane dehydrogenation reaction. [ABSTRACT FROM AUTHOR]

Photocatalytic synthesis of hydrogen peroxide (H 2 O 2) coupled with benzyl alcohol (BA) oxidation reaction is preferred based on the economic consideration. Herein, we developed a hydrophobic TiO 2 material (DNOPA-TiO 2), co-modified with 2,3-dihydroxynaphthalene (2,3-DN) and octadecylphosphonic acid (OPA), which enables H 2 O 2 synthesis under visible-light-irradiation in a two-phase system consisting of BA and water. This system allows the separation of generated H 2 O 2 in the aqueous phase from benzaldehyde (BAL), the product of BA oxidation, present in the organic phase. The hydrophobic DN2OPA2-TiO 2 exhibited higher and more stable H 2 O 2 production (3522 μmol L−1) over an 8-hour reaction under visible light (λ > 450 nm). The addition of 2,3-DN facilitates visible light harvesting and donates electrons to TiO 2 through the formation of charge-transfer complexes, which promotes the O 2 reduction reaction (ORR) and improves H 2 O 2 production. Moreover, the remarkable stability of DN2OPA2-TiO 2 is originated from the hydrophobic nature of the catalysts thanks to OPA modification. This modification allows TiO 2 to exist in the organic phase with better dispersion, inhibiting the decomposition of H 2 O 2 resulting from direct contact between produced H 2 O 2 and TiO 2. [Display omitted] • DN/OPA-TiO 2 is used for photocatalytic H 2 O 2 production in a two-phase system. • 2,3-DN enhances visible light absorption by forming charge-transfer complexes. • OPA imparts TiO 2 hydrophobic and inhibits the decomposition of produced H 2 O 2. • DN2OPA2-TiO 2 exhibits higher visible-light activity (3522 μmol L−1, λ > 450 nm). [ABSTRACT FROM AUTHOR]

The inside back cover of the journal "Chemistry: A European Journal" is presented.

Carbon/g-C 3 N 4 composites (C/g-C 3 N 4 ) with various carbon contents have been prepared by a simple experimental protocol from glucose and dicyandiamide. The results of the characterization of the as-prepared materials indicated that the skeleton structure of g-C 3 N 4 was not altered upon formation of the composite supports and the resulting composites showed a gradual increasing light harvesting capability with the carbon content. Ru-supported catalysts were synthesized from C/g-C 3 N 4 and assessed in the ammonia borane dehydrogenation reaction under dark and visible light irradiation conditions. The enhanced performance displayed by Ru/C/g-C 3 N 4 photocatalysts as compared to Ru/g-C 3 N 4 counterpart might be the result of the effect of the addition of carbon in dispersing and stabilizing small Ru nanoparticles and enhancing the optical absorption properties. [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]

The catalytic ability of graphitic carbon nitride (g-C 3 N 4)-supported composition-controlled PdCo catalysts towards H 2 generation from the formic acid dehydrogenation reaction was assessed in this study and a noticeable composition dependence was evidenced. It was seen that the alloying effect combined with the nitrogen functionalities present on g-C 3 N 4 assisted the formation of small and well-distributed nanoparticles. This fact, combined with the electronic promotion of Pd species via charge transfer from Co and basic features of the support, resulted in enhanced catalytic activities compared to that displayed by the counterpart Pd/g-C 3 N 4 , reaching a TOF value of 1193 h−1 for the most active catalyst among investigated (PdCo/g-C 3 N 4 (1/0.7)). Furthermore, the present catalytic system showed high selectivity towards formic acid dehydrogenation, suppressing the generation of undesired CO via formic acid dehydration, which makes it a suitable candidate for practical application in fuel cells. Image 1 • Small NPs achieved because of alloying effect and N-functionalities of the support. • Electronic promotion of Pd species via charge transfer from Co. • Activity of PdCo/g-C 3 N 4 related to the size of NP, composition and electronic state. • PdCo/g-C 3 N 4 (1/0.7) was the most active among investigated with a TOF of 1193 h−1. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Pd/N-doped carbon xerogels for the formic acid dehydrogenation were synthetized. • The effect of pore texture and N content was investigated. • The presence of N-functionalities is beneficial for the final catalytic activity. • An initial TOF value of 2014 h−1 on the basis of the total Pd loading was obtained. Abstract N-doped carbon xerogels synthesized from melamine-resorcinol-formaldehyde aqueous gels were used as supports for the preparation of Pd-based catalysts for the formic acid dehydrogenation reaction. The effect of the pore texture and nitrogen content of the carbon xerogels on the catalytic activity for the hydrogen production was investigated. It was observed that an appropriate nitrogen doping in a well-defined micro-mesoporous carbon xerogel enables the preparation of Pd catalysts with appreciable catalytic enhancement towards the formic acid dehydrogenation as compared to the N-free counterpart, reaching an initial TOF value of 2014 h−1. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The importance of H 2 in the renewable and pollutant-free energy scenario is pointed out. • Synthetic strategies of N-doped carbon materials and related catalysts are summarized. • HCOOH, NH 3 BH 3 and H 2 O are exemplified as hydrogen molecular carriers. • N-functionalities play a key role in attaining highly performing catalysts for H 2 production. Abstract Nitrogen-doped carbon materials have emerged as versatile candidates with outstanding features as both support of metal-based catalysts and metal-free catalytic systems. Their use has been traditionally linked to electrochemical applications, but the number of applications in which these materials show their virtues has been exponentially increasing in the last decade. Particularly, catalysts based on metal nanoparticles supported on nitrogen-doped carbon materials have shown to be attractive for important catalytic reactions as they display enhanced performances endowed by well-dispersed, stabilized and electronically promoted nanoparticles as well as by the modified acid-base properties of the support. The present review is focused on the most recent breakthroughs achieved by these catalytic systems in the hydrogen production from some of the most representative hydrogen carrier molecules by highlighting the effect of the incorporation of nitrogen in the support matrix. [ABSTRACT FROM AUTHOR]

Highly efficient carbon-supported Ru catalysts towards the H 2 production from the ammonia borane (AB: NH 3 BH 3 ) hydrolysis reaction have been developed by using tri(2,2′-bipyridyl) ruthenium (II) chloride hexahydrate as metal precursor. Different temperatures were used to decompose the metal precursor, which afford the preparation of various nanoparticles sizes, ranging from 3.8 to 13.5 nm. The catalytic results revealed that both geometric and electronic features of the metal nanoparticles are crucial to attain optimum catalytic activity towards the H 2 production from the hydrolysis of AB. The optimum catalyst under the experimental condition used was that prepared at 800 °C, which efficiently boosts the hydrolysis of AB, achieving an average TOF number of 670 mol H 2 /mol metal min, which is among the highest values ever reported for a monometallic Ru catalyst in this reaction up to date. [ABSTRACT FROM AUTHOR]