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In this work, the mechanical lap joint of commercial ReBCO tape from SHSC is prepared. The tape is reinforced with stainless steel bar in both side to reduce the effect of bending moment in the joint tensile test. We use Indium and GaInSn as interlayer material, respectively, and different pressures are applied on the joint by jig during testing. The relationship between joint resistance and applied tensile stress was measured at 77 K. The results shows that for all measured joints under pressure, the voltage rise duo to tensile stress is small at first and then sharply grows until a certain value of stress is reached. The maximum tensile stress is higher for the joint which has lower resistance. Comparing two types of mechanical lap joints with Indium and GaInSn, the former joint shows smaller dispersion on joint resistance than the latter under pressure above 40 Mpa. It is also shown that the joint with Indium can tolerate higher tensile stress than the joint with GaInSn by using the Weibull distribution function analysis.

Applying metal-organic frameworks (MOFs) on the surface of other materials to form multifunctional materials has recently attracted great attention; however, directing the MOF overgrowth is challenging due to the orders of magnitude differences in structural dimensions. In this work, we developed a universal strategy to mediate MOF growth on the surface of metal nanoparticles (NPs), by taking advantage of the dynamic nature of weakly adsorbed capping agents. During this colloidal process, the capping agents gradually dissociate from the metal surface, replaced

The pursuit of two-dimensional (2D) borides, MBenes, has proven to be challenging, not the least because of the lack of a suitable precursor prone to the deintercalation. Here, we studied room-temperature topochemical deintercalation of lithium from the layered polymorphs of the LiNiB compound with a considerable amount of Li stored in between [NiB] layers (33 at. % Li). Deintercalation of Li leads to novel metastable borides (Li similar to 0.5NiB) with unique crystal structures. Partial removal of Li is accomplished by exposing the parent phases to air, water, or dilute HCl under ambient conditions. Scanning transmission electron microscopy and solid-state Li-7 and B-1(1) NMR spectroscopy, combined with X-ray pair distribution function (PDF) analysis and DFT calculations, were utilized to elucidate the novel structures of (Li similar to 0.5NiB) and the mechanism of Li-deintercalation. We have shown that the deintercalation of Li proceeds via a "zip-lock" mechanism, leading to the condensation of single [NiB] layers into double or triple layers bound via covalent bonds, resulting in structural fragments with Li[NiB](2) and Li[NiB](3) compositions. The crystal structure of Li similar to 0.5NiB is best described as an intergrowth of the ordered single [NiB], double [NiB](2), or triple [NiB](3) layers alternating with single Li layers; this explains its structural complexity. The formation of double or triple [NiB] layers induces a change in the magnetic behavior from temperature-independent paramagnets in the parent LiNiB compounds to the spin-glassiness in the deintercalated Li similar to 0.5NiB counterparts. LiNiB compounds showcase the potential to access a plethora of unique materials, including 2D MBenes (NiB).

The study of the reaction mechanism and complex network for heterogeneously catalyzed tandem reactions is challenging but can guide reaction design and optimization. Here, we describe a case study using bifunctional metal–organic framework supported Pd nanoparticles (Pd/UiO-66(HCl)) for the one-pot tandem synthesis of substituted tetrahydroquinolines via the Claisen–Schmidt condensation and reductive intramolecular cyclization. The directly observed evolution of intermediates and products, including reactive species containing hydroxylamine group and unstable intermediate 2-phenyl-3,4-dihydroquinoline, was enabled by operando magic angle spinning nuclear magnetic resonance studies under 50 bar H2. The reaction network of the tandem reaction is deduced based on reaction kinetic information obtained from the operando study. The optimized procedure was applied to various acetophenone and nitrobenzaldehyde derivatives carrying different functional groups, and eight valuable substituted tetrahydroquinolines were obtained in moderate to good yields. This work provides a molecular-level understanding of the catalytic system and brings up new opportunities for efficient and sustainable synthesis of medicinally relevant building blocks.

Harmful algae blooms represent a serious problem for natural waters around the world, and have a great impact on water quality, local economies and human health. To tackle the above challenge, we successfully prepare fluorine-doped titanium oxide (F-TiO2) nanocomposites by a hydrothermal method as a photocatalytic algaecide. The synthesized nanocomposites were characterized by SEM (scanning electron microscope), EDS (energy dispersive spectrometer), XPS (X-ray photoelectron spectroscopy), XRD (X-ray diffraction), and EPR (electron paramagnetic resonance). The results of this study indicated that the crystallinity of anatase in F-TiO2 is enhanced significantly upon fluorine doping. F-TiO2 with a dosage of 0.75 g L−1 exhibited the best anti-algae activity, and the removal rate of algae cells is above 97.5% under solar irradiation for 8 h. When the potential of hydrogen (pH) value was 10.0, F-TiO2 had a good treatment effect. When the pH value was lower than 6.25, it was beneficial to the decline of the chlorophyll a content. The inactivation process of F-TiO2 inhibiting Microcystis aeruginosa fits well with the improved Chick–Waston model and Hom model. During the photocatalytic destruction, fluorine-doped TiO2 oxidized the algae cell walls and membranes, simultaneously degrading the metabolic products and microcystin-LR with high efficiency. The reactive oxygen species contribution of the F-TiO2 photocatalyst in the process of photocatalytic algae removal is h+ > ˙OH > ˙O2−. Compared with traditional algae removal methods, photocatalytic algaecides can rapidly prevent secondary pollution while improving efficiency, and using solar light as an energy source is more suitable for in situ remediation of natural water bodies.

The overconsumption of single-use plastics is creating a global waste catastrophe, with widespread environmental, economic and health-related consequences. Here we show that the benefits of processive enzyme-catalysed conversions of biomacromolecules can be leveraged to affect the selective hydrogenolysis of high-density polyethylene into a narrow distribution of diesel and lubricant-range alkanes using an ordered, mesoporous shell/active site/core catalyst architecture that incorporates catalytic platinum sites at the base of the mesopores. Solid-state nuclear magnetic resonance revealed that long hydrocarbon macromolecules readily move within the pores of this catalyst, with a subsequent escape being inhibited by polymer–surface interactions, a behaviour that resembles the binding and translocation of macromolecules in the catalytic cleft of processive enzymes. Accordingly, the hydrogenolysis of polyethylene with this catalyst proceeds processively to yield a reliable, narrow and tunable stream of alkane products. Achieving plastic deconstruction with high selectivity is crucial for upcycling schemes, but remains challenging. Here, a processive approach for the selective hydrogenolysis of high-density polyethylene into narrow alkane fractions is introduced relying on a Pt/SiO2 catalyst encapsulated in a mesoporous silica shell.

Bimetallic catalysts are gaining flourishing research interest due to their tunable electronic and geometric structure over monometallic catalysts. Herein, we prepare a series of Pt–Sn nanoparticle...

Multifunctional metal-organic frameworks (MOFs) that possess permanent porosity are promising catalysts in organic transformation. Herein, we report the construction of a hierarchical MOF functionalized with basic aliphatic amine groups and polyvinylpyrrolidone-capped platinum nanoparticles (Pt NPs). The postsynthetic covalent modification of organic ligands increases basic site density in the MOF and simultaneously introduces mesopores to create a hierarchically porous structure. The multifunctional MOF is capable of catalyzing a sequential Knoevenagel condensation-hydrogenation-intramolecular cyclization reaction. The unique selective reduction of the nitro group to intermediate hydroxylamine by Pt NPs supported on MOF followed by intramolecular cyclization with a cyano group affords an excellent yield (up to 92%) to the uncommon quinoline N-oxides over quinolines. The hierarchical MOF and polyvinylpyrrolidone capping agent on Pt NPs synergistically facilitate the enrichment of substrates and thus lead to high activity in the reduction-intramolecular cyclization reaction. The bioactivity assay indicates that the synthesized quinoline N-oxides evidently inhibit the proliferation of lung cancer cells. Our findings demonstrate the feasibility of MOF-catalyzed direct synthesis of bioactive molecules from readily available compounds under mild conditions.

Photo-Fenton processes have been widely studied in wastewater treatment. In this research, the degradation of bisphenol A (BPA) was carried out in a new heterogeneous photo-Fenton process. The ethylenediamine-N,N′-disuccinic acid (EDDS) was used as chelating agent in this system with two different kinds of commercially available nanosized hematite (30 nm and 80 nm) addition. The results showed that the present of EDDS could enhance the degradation efficiency. And can be concluded that the degradation efficiency is better in the system with 30 nm hematite. The TEM, XRD, and specific surface area were conducted to understand the different characteristics of the two size hematite. The adsorption experiments of BPA and EDDS on hematite proved that there was little adsorption of BPA while the EDDS was adsorbed much more on hematite, which has confirmed Fe(III) and EDDS can form Fe(III)-EDDS complex. The effects of different parameters including hematite loading, H2O2, and EDDS concentrations on the degradation process were investigated. According to the results, the optimum condition for BPA degradation using 30 nm (0.8 g L−1 hematite, 0.1 mmol L−1 H2O2, and 1.2 mmol L−1 EDDS) and 80 nm (0.6 g L−1 hematite, 0.05 mmol L−1 H2O2, and 1.2 mmol L−1 EDDS) hematite were selected. It was confirmed that the ·OH plays an important role in the oxidation process through attacking the BPA molecule and produce hydroxyl addition derivative. In addition, O2 can react with electron (e−) and holes (h+) produced by iron oxide under UV irradiation to create 1O2, which could work as potential reactive species to oxidize BPA.

Hyperpolarized propane produced by heterogeneous hydrogenation of cyclopropane with parahydrogen has been proposed as a safe inhalant for sensitivity-enhanced in vivo magnetic resonance imaging. Th...

International audience; In this study, a series of Fe-doped g-C3N4 (Fe–C3N4) samples was synthesized and characterized via X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflection spectroscopy (UV-vis DRS), and photoluminescence (PL) spectroscopy. The photocatalytic activity of the synthesized Fe–C3N4 was investigated toward methylene blue (MB) degradation with hydrogen peroxide (H2O2) assistance. The results showed that the Fe–C3N4 heterogeneous photo-Fenton-like system showed excellent catalytic performance when the pH value was varied from 3.0 to 9.0. Evaluating the effects of various inorganic anions in the Fe–C3N4 heterogeneous photo-Fenton-like system, HCO3− showed a dual effect on MB degradation, and Cl− and NO3− showed an inhibitory effect on MB degradation. Evaluating the effects of inorganic cations, Al3+, Mg2+, and Ca2+ strongly inhibited MB degradation. Recycling experiments demonstrated that Fe–C3N4 possesses good reusability and stability. Quenching experiments were carried out, and it was found that hydroxyl radicals (·OH) were the primary active species in the system. Besides, nine intermediates were identified via LC/MS, and a possible MB degradation pathway in the system was proposed. This study could promote the application of this Fe–C3N4 heterogeneous photo-Fenton-like system in realistic dye wastewater.

The molecular basis for the high cis-alkene selectivity over intermetallic PtSn for alkyne semi-hydrogenation is demonstrated. Unlike the universal assumption that the bimetallic surface is saturated with atomic hydrogen, molecular hydrogen has a higher barrier for dissociative adsorption on intermetallic PtSn due to the deficiency of Pt three-fold sites. The resulting molecular behavior of adsorbed hydrogen on intermetallic PtSn nanoparticles leads to pairwise-hydrogenation of three alkynes to the corresponding cis-alkenes, satisfying both high stereoselectivity and high chemoselectivity.

Hydroformylation is an imperative chemical process traditionally catalyzed by homogeneous catalysts. Designing a heterogeneous catalyst with high activity and selectivity in hydroformylation is challenging but essential to allow the convenient separation and recycling of precious catalysts. Here, we report the development of an outstanding catalyst for efficient heterogeneous hydroformylation, RhZn intermetallic nanoparticles. In the hydroformylation of styrene, it shows three times higher turnover frequency (3090 h-1) compared to the benchmark homogeneous Wilkinson's catalyst (966 h-1), as well as a high chemoselectivity toward aldehyde products. RhZn is active for a variety of olefin substrates and can be recycled without a significant loss of activity. Density functional theory calculations show that the RhZn surfaces reduce the binding strength of reaction intermediates and have lower hydroformylation activation energy barriers compared to pure Rh(111), leading to more favorable reaction energetics on RhZn. The calculations also predict potential catalyst design strategies to achieve high regioselectivity.

International audience; Owing to their diverse functional groups, antibiotics can easily form complexes with heavy metals; the complexation alters the migration and transformation behavior of both antibiotics and heavy metals. In this study, we investigated the co-adsorption mechanism of sulfamethazine (SMT) and cadmium (Cd2+) heavy metal ions and created an ideal water model containing two major contaminants: sulfamethazine and heavy metal cadmium ions. Combined with the experimental analysis of the interaction mechanism, the results indicate the heterogeneous multilayer adsorption of SMT on the surface of activated carbon (AC). The bridging role of cadmium ions promotes the adsorption of SMT through the formation of SMT-Cd2+-AC ternary complexes on the surface of activated carbon. Characterization experiments provided further insight into the adsorption behavior of Cd2+ and SMT on activated carbon, revealing a strong correlation between the Cd2+-SMT complexation and the SMT adsorption capacity. These results indicate that the effects of the coexistence of antibiotics and heavy metal ions should be fully taken into account when investigating the environmental behavior of antibiotics and heavy metal ions.

Nanoconfinement could dramatically change molecular transport and reaction kinetics in heterogeneous catalysis. Here we specifically design a core-shell nanocatalyst with aligned linear nanopores for single-molecule studies of the nanoconfinement effects. The quantitative single-molecule measurements reveal unusual lower adsorption strength and higher catalytic activity on the confined metal reaction centres within the nanoporous structure. More surprisingly, the nanoconfinement effects on enhanced catalytic activity are larger for catalysts with longer and narrower nanopores. Experimental evidences, including molecular orientation, activation energy, and intermediate reactive species, have been gathered to provide a molecular level explanation on how the nanoconfinement effects enhance the catalyst activity, which is essential for the rational design of highly-efficient catalysts., Nanoconfinement effects on changing molecular transport and reaction kinetics in heterogeneous catalysis have been widely recognized. Here, the authors design a core-shell nanocatalyst with aligned linear nanopores to uncover nanoconfinement effects on catalytic activity and adsorption strength by single molecule imaging.

The design of efficient catalysts capable of delivering high currents at low overpotentials for hydrogen evolution reactions (HERs) is urgently needed to use catalysts in practical applications. Herein, we report platinum (Pt) alloyed with titanium (Ti) from the surface of Ti3C2Tx MXenes to form Pt3Ti intermetallic compound (IMC) nanoparticles (NPs) via in situ coreduction. In situ X-ray absorption spectroscopy (XAS) indicates that Pt undergoes a temperature-dependent transformation from single atoms to intermetallic compounds, and the catalyst reduced at 550 °C exhibits a superior HER performance in acidic media. The Pt/Ti3C2Tx-550 catalyst outperforms commercial Pt/Vulcan and has a small overpotential of 32.7 mV at 10 mA cm-2 and a low Tafel slope of 32.3 mV dec-1. The HER current was normalized by the mass and dispersion of Pt, and the mass activity and specific activity of Pt/Ti3C2Tx-550 are 4.4 and 13 times higher, respectively, than those of Pt/Vulcan at an overpotential of 70 mV. The density functional theory (DFT) calculations suggest that the (111)- and (100)-terminated Pt3Ti nanoparticles exhibit *H binding comparable to Pt(111), while the (110) termination has an *H adsorption that is too exergonic, thus poisoned in the low overpotential region. This work demonstrates the potential of MXenes as platforms for the design of electrocatalysts and may spur future research for other MXene-supported metal catalysts that can be used for a wide range of electrocatalytic reactions.

Research and development in bimetallic nanoparticles have gained great interest over their monometallic counterparts because of their distinct and unique properties in a wide range of applications such as catalysis, energy storage, and bio/plasmonic imaging. Identification and characterization of these bimetallic surfaces for application in heterogeneous catalysis remain a challenge and heavily rely on advanced characterization techniques such as aberration-corrected electron microscopy and synchrotron X-ray absorption studies. In this article, we have reported a strategy to prepare sub-2 nm bimetallic Pt-Sn nanoclusters confined in the pores of a Zr-based metal-organic framework (MOF). The Pt-Sn nanoclusters encapsulated in the Zr-MOF pores show enhanced chemoselectivity from 51 to 93% in an industrially relevant reaction, furfural hydrogenation to furfuryl alcohol. The presence of bimetallic Pt-Sn surfaces was investigated by a surface-sensitive characterization technique utilizing diffuse reflectance infrared Fourier transform spectroscopy of adsorbed CO to probe the bimetallic surface of the encapsulated ultrafine Pt-Sn nanocluster. Complementary techniques such as aberration-corrected high-angle annular dark-field scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were also used to characterize the Pt-Sn nanoclusters.

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales. However, predictive modeling requires incorporation of realistic rates for relaxation mechanisms, e.g., periphery diffusion and intermixing, in numerous local environments (rather than the use of generic prescriptions). Alternative coarse-grained modeling must also incorporate appropriate mechanisms and kinetics. At the level of individual NCs, we present analyses of reshaping, including sintering and pinch-off, and of compositional evolution in a vacuum environment. We also discuss modeling of coarsening including diffusion and decay of individual NCs and unconventional coarsening processes. We describe high-level modeling integrated with scanning tunneling microscopy (STM) studies for supported 2D epitaxial nanoclusters and developments in modeling for 3D NCs motivated by in situ transmission electron microscopy (TEM) studies.

Intermetallic compounds are unique catalyst platforms for mechanistic studies and industrial applications, because of their ordered structures in comparison to random alloys. Despite the intrinsically defined stoichiometry of intermetallic compounds, compositional deviations can still occur in intermetallic catalysts. The location of the extra metal atoms could differ the catalytic properties of intermetallic compounds with non-stoichiometric composition if those metal atoms end up on/near the surface. In this study, we synthesized PtSn intermetallic compounds with accurate stoichiometry and slightly Pt-/Sn-rich compositions. We used furfural hydrogenation and acetylene semi-hydrogenation as probe reactions to investigate the surface structures of PtSn intermetallic catalysts after reduction at different temperatures. Even though the intermetallic PtSn is the major bulk phase among non-stoichiometric compositions, the intermetallic PtSn surface can only be observed under the high-temperature reduction in Sn-rich PtSn intermetallic nanoparticles (iNPs), while the Pt-rich PtSn iNPs show Pt-rich-surfaces regardless of reduction temperatures. Four structural models were constructed based on the comprehensive surface and bulk characterizations. This work extends the understanding of intermetallic catalysts with non-stoichiometric compositions to tailor the intermetallic surface structures for catalysis.

The high glucose (HG)-induced epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) serves an important role in peritoneal fibrosis (PF) during peritoneal dialysis. Our previous study reported that zinc (Zn) supplementation prevented the HG-induced EMT of rat PMCs in vitro. In the present study, the role of Zn in HG-induced EMT was investigated in vivo using a rat model of PF. Additionally, the molecular mechanisms underlying HG-induced EMT were studied in human PMCs (HPMCs). In the rat model of PF, HG treatment increased the glucose transfer capacity and decreased the ultrafiltration volume. Histopathological analysis revealed peritoneal thickening, increased expression of vimentin and decreased expression of E-cadherin. ZnSO4 significantly ameliorated the aforementioned changes, whereas Zn inhibition by clioquinol significantly aggravated the effects of HG on rats. The effects of Zn on HPMCs was assessed using western blot analysis, Transwell assays and flow cytometry. It was revealed that Zn also significantly suppressed the extent of the EMT, and reduced reactive oxygen species production and the migratory ability of HG-induced HPMCs, whereas Zn inhibition by N',N',N',N'-tetrakis (2-pyridylmethyl) ethylenediamine significantly potentiated the HG-induced EMT of HPMCs. HG-stimulated HPMCs exhibited increased expression of nuclear factor-like 2 (Nrf2) in the nucleus, and total cellular NAD(P)H quinone dehydrogenase 1 (NQO1) and heme oxygenase-1 (HO-1), the target proteins of the Nrf2 antioxidant pathway. Zn supplementation further promoted nuclear Nrf2 expression, and increased the expression of target proteins of the Nrf2 antioxidant pathway, whereas Zn depletion decreased nuclear Nrf2, NQO1 and HO-1 expression compared with the HG group. In conclusion, Zn supplementation was proposed to suppress the effects of HG on the EMT by stimulating the Nrf2 antioxidant pathway and subsequently reducing oxidative stress in PMCs.

Mesoporous silica encapsulated Pt (Pt@mSiO(2)) and PtSn (PtSn@mSiO(2)) nanoparticles (NPs) are representatives of a novel class of heterogeneous catalysts with uniform particle size, enhanced catalytic properties, and superior thermal stability. In the ship-in-a-bottle synthesis, PtSn@mSiO(2) intermetallic NPs are derived from Pt@mSiO(2) seeds where the mSiO(2) shell is formed by polymerization of tetraethyl orthosilicate around a tetradecyltrimethylammonium bromide template, a surfactant used to template MCM-41. Incorporation of Sn into the Pt@mSiO(2) seeds is accommodated by chemical etching of the mSiO(2) shell. The effect of this etching on the atomic-scale structure of the mSiO(2) has not been previously examined, nor has the extent of the structural similarity to MCM-41. Here, the quaternary Q(2), Q(3) and Q(4) sites corresponding to formulas Si(O(1/2))(2)(OH)(2), Si(O(1/2))(3)(OH)(1) and Si(O(1/2))(4), in MCM-41 and the mesoporous silica of Pt@mSiO(2) and PtSn@mSiO(2) NPs were identified and quantified by conventional and dynamic nuclear polarization enhanced Si-29 Magic Angle Spinning Nuclear Magnetic Resonance (DNP MAS NMR). The connectivity of the -Si-O-Si-network was revealed by DNP enhanced two-dimensional (29)Si-(29)Si correlation spectroscopy.

Selective oxidation of olefins to α,β-unsaturated ketones under mild reaction conditions has attracted considerable interest, since α,β-unsaturated ketones can serve as synthetic precursors for various downstream chemical products. The major inherent challenges with this chemical oxidation are chemo- and regio-selectivity as well as environmental concerns, i.e. catalyst recycle, safety and cost. Using atmospheric oxygen as an environmentally friendly oxidant, we found that a metal–organic framework (MOF) constructed with Mn and a tetrazolate ligand (CPF-5) showed good activity and selectivity for the allylic oxidation of olefins to α,β-unsaturated ketones. Under the optimized conditions, we could achieve 98% conversion of cyclohexene and 87% selectivity toward cyclohexanone. The combination of a substoichiometric amount of TBHP (tert-butylhydroperoxide) and oxygen not only provides a cost effective oxidation system but significantly enhances the selectivity to α,β-unsaturated ketones, outperforming most reported oxidation methods. This catalytic system is heterogeneous in nature, and CPF-5 could be reused at least five times without a significant decrease in its catalytic activity and selectivity.

Highly dispersed Co sites in highly porous N-doped carbon (Co-NC) were synthesized by high-temperature pyrolysis of Zn/Co bimetallic zeolitic imidazolate framework-8 (CoxZn100−x-ZIF). Wide characterization indicated that the pyrolysis atmosphere and temperature play crucial roles in the metal dispersion and pore structure of the resulting materials. A hydrogen treatment at elevated temperatures is found to favour the Zn volatilization and restrict the pore shrinkage of the ZIF precursor, thus yielding efficient catalysts with highly dispersed Co, a high surface area (1090 m2 g−1) and pore volume (0.89 cm3 g−1). When used as a catalyst for aerobic oxidation of ethylbenzene (EB), Co1Zn99-ZIF-800-H2 contributes to 98.9% EB conversion and 93.1% ketone selectivity under mild conditions (60 °C, 1 atm O2), which is 41.3 times more active in comparison to the ZIF-67-derived Co catalyst. Co-NC is stable and could be reused four times without obvious deactivation. This catalyst displays good chemoselectivity to the corresponding ketones when using a broad scope of hydrocarbon compounds.

Tandem catalysis, often inspired by biological systems, offers many advantages in the synthesis of highly functionalized small molecules. NH2-grafted porous C3N4 nanosheet with rich N species and surface area of 138 m2/g was fabricated via a NH3-exfoliation method. After supporting Pd nanoparticles, the resulting bifunctional catalyst (Pd/C3N4–NH2) could catalyze a one-step tandem condensation-hydrogenation reaction between ketones and nitriles to form α-alkylated nitriles at room temperature. Under 2 MPa H2 for 8 h, Pd/C3N4–NH2 could afford 99.7% cyclohexanone conversion and 99.8% selectivity without other side reactions, which is much higher than that of bulk C3N4-supported Pd. Compared with commonly used two-step processes, this one-step tandem reaction could largely shorten reaction time and allow condensation-hydrogenation to take place at room temperature. We also found that the hydrogenation step accelerated the condensation step, which increased the overall efficiency of the tandem transformation....

A versatile and straightforward room-temperature strategy is demonstrated to synthesize boundary defect-rich ultrathin transition metal hydroxide nanosheet networks by in situ etching of a cobalt metal–organic framework (Co-MOF, ZIF-L-Co). The resultant defect-rich ultrathin Co(OH)2 (D-U-Co(OH)2) nanoarray is one of the most active monometal-based oxygen evolution catalysts to date. Its activity is 3–4 times higher than that of the commercial RuO2 and superior to that of the reported exfoliated bimetallic catalysts. Co-MOF can also be grown on various substrates, and the chemical composition of the defect-rich 2D materials is tunable by changing the metal ions in the etchants. Owing to these merits of the unique synthesis route, our work provides an opportunity for synthesizing advanced nanomaterials that are difficult to get access to by conventional methods.

Background: Injectable somatostatin receptor ligands (iSRLs) have been a mainstay in acromegaly treatment. Oral octreotide capsules (OOC; MYCAPSSA®) were recently approved in the United States. Results from the placebo-controlled CHIASMA OPTIMAL and open-label CH-ACM-01 studies showed an OOC safety profile consistent with that of iSRLs with no new or unexpected safety signals. Results of the MPOWERED trial have enabled a comparison of OOC safety and efficacy with iSRLs. Methods: To enter MPOWERED, patients must have the following: acromegaly diagnosis, biochemical control of acromegaly (insulin-like growth factor I Results: In the RCT, incidence of treatment-emergent adverse events (TEAEs) was similar between groups; 39 patients (70.9%) in the OOC group and 26 (70.3%) in the iSRL group had ≥1 TEAE. 19 patients (34.5%) in the OOC and 15 (40.5%) in the iSRL group had treatment-related TEAEs. Occurrence was similar for serious AEs (OOC, 5.5%; iSRL, 8.1%) as well as TEAEs classified as severe (OOC, 9.1%; iSRL, 10.8%). One patient in the OOC group discontinued due to a TEAE. The most common gastrointestinal TEAEs were flatulence (OOC, 25.5%; iSRL, 21.6%), nausea (OOC, 20.0%; iSRL, 8.1%), diarrhea (OOC, 10.9%; iSRL, 13.5%), abdominal pain (OOC, 9.1%; iSRL, 8.1%), and constipation (OOC, 5.5%; iSRL, 13.5%). AEs of interest were infrequent, including cholelithiasis (OOC, n=0; iSRL, n=1 [2.7%]) and secondary hypothyroidism (OOC, n=1 [1.8%]; iSRL, n=0). In the iSRL group, 32.4% of patients reported injection site reactions (ISRs) during the RCT, and 47% of patients reported ISRs as part of the Acromegaly Treatment Satisfaction Questionnaire, a newly validated patient-reported outcome tool.1 Conclusion: Safety results from MPOWERED align with prior trials, showing that the OOC safety profile is consistent with that of iSRLs as well as the acromegaly disease burden. No new or unexpected safety signals were identified during the trial. Safety results were mostly similar between OOC and iSRLs, although patients in the OOC group did not experience any ISRs. 1Fleseriu M, et al. Pituitary. 2020 Aug;23(4):347-358.

Heterogeneous single-metal-site catalyst or single-atom catalyst research has grown rapidly due to the accessibility of modern characterization techniques that can provide invaluable information at the atomic-scale. Herein, we study the structural evolution of isolated single Pt sites incorporated in a metal–organic framework containing bipyridine functional groups using in situ diffuse reflectance infrared Fourier transform spectroscopy with CO as the probe molecule. The structure and electronic properties of the isolated Pt sites are further corroborated by x-ray photoelectron spectroscopy and aberration-corrected scanning transmission electron microscopy. We find the prerequisite of high temperature He treatment for Pt activation and CO insertion and inquire into the structural transformation of Pt site process by dynamic nuclear polarization-enhanced solid-state nuclear magnetic resonance spectroscopy.

The van der Waals (vdW) chromium trihalides (CrX3) exhibit field-tunable, two-dimensional magnetic orders that vary with the halogen species and the number of layers. Their magnetic ground states with proximity in energies are sensitive to the degree of ligand-metal (p-d) hybridization and relevant modulations in the Cr d-orbital interactions. We use soft X-ray absorption (XAS) and resonant inelastic X-ray scattering (RIXS) spectroscopy at Cr L-edge along with the atomic multiplet simulations to determine the key energy scales such as the crystal field 10 Dq and interorbital Coulomb interactions under different ligand metal charge transfer (LMCT) in CrX3 (X= Cl, Br, and I). Through this systematic study, we show that our approach compared to the literature has yielded a set of more reliably determined parameters for establishing a base Hamiltonian for CrX3.

Heterogenous ferrum-based materials usually suffer from large overpotential between the redox of Fe3+/Fe2+ and two-electron oxygen reduction reaction (2e- ORR), leading to less desired performance in electro-Fenton (EF) process. Herein, heterogeneous vanadium oxide EF system (VO-EF) was proposed by electrodepositing VO on carbon paper cathode (VOx@CP) and anode (V3O7@CP) for levofloxacin degradation. The VOx@CP cathode showed the optimal potential of 2e- ORR at -0.90 V (vs. SCE) with H2O2 generation rate of 1.44 × 10-4 mmol·L-1·cm-2·s-1. Though overpotential disparity of 0.35 V was exhibited between the redox of VOx and 2e- ORR, rapid H2O2 consumption rate was still achieved and facilitated ·OH generation. The oxygen vacancies existed in V3O7@CP anode reduced oxygen evolution reaction potential, leading to the cell voltage decrease of 0.36 V. Levofloxacin (30 mg·L-1) degradation efficiency of 97.67% was achieved in the VO-EF system within 120 min, and 19.19 mg·L-1 TOC was mineralized with energy consumption of 12.3 J·mg·L-1 TOC under neutral pH condition. Complete mineralization and low H2O2 residue allowed good bioavailability in the effluent. Levofloxacin degradation pathways and mechanism were proposed based on identified intermediates and theoretical calculation. This study provides inspiration for developing novel EF systems for efficient pollutants degradation.

Nuclear spin hyperpolarization derived from parahydrogen can enable nuclear magnetic resonance spectroscopy and imaging with sensitivity enhancements exceeding four orders of magnitude. The NMR signal enhancement is proportional to 4 x p - 1 , where x p is the parahydrogen mole fraction. For convenience, many labs elect to carry out the ortho–para conversion at 77 K where 50% enrichment is obtained. In theory, enrichment to 100% yields an automatic three-fold increase in the NMR signal enhancement. Herein, construction and testing of a simple and inexpensive continuous-flow converter for high para-enrichment is described. During operation, the converter is immersed in liquid helium contained in a transport dewar of the type commonly found in NMR labs for filling superconducting magnets. A maximum enrichment of 97.3 ± 1.9% at 30 K was observed at 4.5 bar and 300 mL/min flow rate. The theoretically predicted 2.9-fold increase in the signal enhancement factor was confirmed in the heterogeneous hydrogenation of propene to propane over a PdIn/SBA-15 catalyst. The relatively low-cost to construct and operate this system could make high parahydrogen enrichment, and the associated increase in the parahydrogen-derived NMR signals, more widely accessible.

Nanoconfinement imposes physical constraints and chemical effects on reactivity in nanoporous catalyst systems. In the present study, we lay the groundwork for quantitative single-molecule measurements of the effects of chemical environment on heterogeneous catalysis in nanoconfinement. Choosing hydrophobicity as an exemplary chemical environmental factor, we compared a range of essential parameters for an oxidation reaction on platinum nanoparticles (NPs) confined in hydrophilic and hydrophobic nanopores. Single-molecule experimental measurements at the single particle level showed higher catalytic activity, stronger adsorption strength, and higher activation energy in hydrophobic nanopores than those in hydrophilic nanopores. Interestingly, different dissociation kinetic behaviors of the product molecules in the two types of nanopores were deduced from the single-molecule imaging data.

Catalytic cleavage of strong bonds including hydrogen-hydrogen, carbon-oxygen, and carbon-hydrogen bonds is a highly desired yet challenging fundamental transformation for the production of chemicals and fuels. Transition metal-containing catalysts are employed, although accompanied with poor selectivity in hydrotreatment. Here we report metal-free nitrogen-assembly carbons (NACs) with closely-placed graphitic nitrogen as active sites, achieving dihydrogen dissociation and subsequent transformation of oxygenates. NACs exhibit high selectivity towards alkylarenes for hydrogenolysis of aryl ethers as model bio-oxygenates without over-hydrogeneration of arenes. Activities originate from cooperating graphitic nitrogen dopants induced by the diamine precursors, as demonstrated in mechanistic and computational studies. We further show that the NAC catalyst is versatile for dehydrogenation of ethylbenzene and tetrahydroquinoline as well as for hydrogenation of common unsaturated functionalities, including ketone, alkene, alkyne, and nitro groups. The discovery of nitrogen assembly as active sites can open up broad opportunities for rational design of new metal-free catalysts for challenging chemical reactions., Metal-free catalysts can offer uniquely different activity and selectivity from transition metal-based counterparts. Here, the authors report metal-free nitrogen-assembly carbon with closely-placed nitrogen as active sites, achieving catalytic cleavage of strong bonds including H-H, C-O and C-H.

Heptazine-based conjugated polymeric carbon nitrides (PCNs) are promising metal-free photocatalysts, yet their synthesis is challenging due to the electron-deficiency and insolubility of heptazine units. Indeed, heptazine-containing polymers have only been prepared through nucleophilic substitution with amines by using toxic cyameluric chloride as the starting material. Herein, we report the novel and environmentally friendly method for preparing heptazine-based mesoporous PCNs with hydrazone links formed through a simple Schiff base condensation of melem-NH2 and aldehydes. Unlike cyameluric chloride, melem-NH2 is non-toxic, stable, and can be readily obtained from melem and hydrazine in solution. We demonstrate that the hydrazone linkages and the heptazine units synergistically enhance the photocatalytic activity of PCNs in visible-light-driven aerobic oxidation of benzyl alcohol to benzaldehyde. In particular, the polymer constructed from melem-NH2 and p-phthalaldehyde shows 17 times more activity than graphitic carbon nitride (g-C3 N4 ).

International audience; The application of carboxylic acid and natural iron oxide in heterogeneous AOP systems for the treatment of organic pollutants in water has attracted extensive attention. In this work, ethylenediamine-N,N′-disuccinic acid (EDDS) was complexed with ferrihydrite to improve the photo-Fenton system for bisphenol A (BPA) degradation, and the mechanism of the system was investigated. TEM, XRD and BET were used to investigate the morphology, structure and specific surface area of ferrihydrite. The characterization results revealed that ferrihydrite was amorphous and agglomerated, its main composition was 2–2lfh, and its specific surface area was 297.5 m2 g−1. BPA degradation experiments, carried out at different influence factors including the initial concentration of EDDS, amount of ferrihydrite and initial concentration of H2O2, showed a maximum degradation rate of BPA of 85.1% under the optimal conditions (at 1.0 mmol L−1 EDDS, 0.6 g L−1 ferrihydrite and 0.5 mmol L−1 H2O2). Finally, in order to analyze the mechanism of BPA degradation, 2-propanol and chloroform were used as free radical scavengers to capture hydroxyl radicals (˙OH) and superoxide anion radicals (˙O2−) respectively. The results indicated that ˙OH radicals and 1O2 play an important role under aerobic conditions, while ˙O2− radicals produced by the reaction of H2O2 and holes are non-negligible under anaerobic conditions. Moreover, the iron dissolution also plays a promoting role in BPA degradation. Overall, Fe(III) and Fe(II) redox processes are accelerated due to the Fe(III)–EDDS complex reaction under irradiation and in the presence of ˙O2− radicals and trace iron dissolution, which increases the number of reactive species in the system. The BPA degradation is facilitated by various reactive species including ˙OH radicals, 1O2 and ˙O2− radicals.

Due to the large radius of K-ion, K-ion batteries (KIBs) involving K-ion insertion and extraction processes generally exhibit an insufficient cycle life and poor rate performance. In this work, sulphur-doped reduced graphene oxide (S-RGO) sponges, which are used as free-standing anodes for KIBs, are obtained via simple freeze-drying of graphene oxide solution and subsequent thermal treatment in sulphur steam. After sulphur doping, our S-RGO sponges deliver preeminent electrochemical performance. Such free-standing electrodes exhibit high K-ion storage capacity of 361 mAh g −1 at 50 mA g −1 over 50 cycles. Furthermore, even at a high current density of 1 A g −1 , they also display a highly stabile K-ion storage with a capacity of 229 mAh g −1 over 500 cycles, which outperforms all previously reported carbon-based materials for KIBs. Such preeminent performance is attributed to the S-RGO sponges’ unique conductive structure and the sulphur doping, which effectively enhance the insertion of large K ions. We also utilize ex-situ XPS to illuminate the reaction process of our sample during potassiation/depotassiation and highlight the role of sulphur doping in improving K-ion storage performance.

Ordered mesoporous N-doped carbon (OMNC) encapsulating Co nanoparticles (NPs) have been prepared under direct polymerization between [Co(NH2CH2CH2NH2)2]Cl2 and carbon tetrachloride through a hard template method. The catalysts (Co@OMNC) are pyrolyzed at various temperatures and characterized by elemental analysis, Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). In the quinoline transfer hydrogenation with formic acid (FA) as the hydrogen source under a base-free condition, the encapsulated Co NPs are physically isolated from the acidic reaction solution, which prevents them from poisoning or leaching. The rich mesopores and N dopants afford enhanced adsorption of quinoline. Co@OMNC-700 (pyrolyzed at 700 °C) gives the best activity (98.8% conversion) as well as >99% 1,2,3,4-tetrahydroquinoline (THQ) selectivity at 140 °C for 4 h, exhibiting significantly improved performance compared to using H2 as the hydrogenation ...

Covalent organic frameworks (COFs) as drug-delivery carriers have been mostly evaluated in vitro due to the lack of COFs nanocarriers that are suitable for in vivo studies. Here we develop a series of water-dispersible polymer-COF nanocomposites through the assembly of polyethylene-glycol-modified monofunctional curcumin derivatives (PEG-CCM) and amine-functionalized COFs (APTES-COF-1) for in vitro and in vivo drug delivery. The real-time fluorescence response shows efficient tracking of the COF-based materials upon cellular uptake and anticancer drug (doxorubicin (DOX)) release. Notably, in vitro and in vivo studies demonstrate that PEG-CCM@APTES-COF-1 is a smart carrier for drug delivery with superior stability, intrinsic biodegradability, high DOX loading capacity, strong and stable fluorescence, prolonged circulation time and improved drug accumulation in tumors. More intriguingly, PEG350-CCM@APTES-COF-1 presents an effective targeting strategy for brain research. We envisage that PEG-CCM@APTES-COF-1 nanocomposites represent a great promise toward the development of a multifunctional platform for cancer-targeted in vivo drug delivery., Despite their potential application as drug-delivery carriers, covalent organic frameworks (COF) have been only evaluated in vitro. Here the authors show by real time tracking in vivo the cell uptake of anticancer-drug loaded and water dispersible COFs.

We report a facile strategy to synthesize intermetallic nanoparticle (iNP) electrocatalysts via one-pot pyrolysis of a zeolitic imidazolate framework, ZIF-8, encapsulating precious metal nanoparticles (NPs). ZIF-8 serves not only as precursor for N-doped carbon (NC), but also as Zn source for the formation of intermetallic or alloy NPs with the encapsulated metals. The resulting sub-4 nm PtZn iNPs embedded in NC exhibit high sintering resistance up to 1,000 °C. Importantly, the present methodology allows fine-tuning of both composition (e.g., PdZn and RhZn iNPs, as well as AuZn and RuZn alloy NPs) and size (2.4, 3.7, and 5.4 nm PtZn) of the as-formed bimetallic NPs. To the best of our knowledge, this is the first report of a metal-organic framework (MOF) with multiple functionalities, such as secondary metal source, carbon precursor, and size-regulating reagent, which promote the formation of iNPs. This work opens a new avenue for the synthesis of highly uniform and stable iNPs.

Noble metal-based bimetallic nanoparticles (NPs) synthesized using colloidal methods always contain organic capping agents. These NPs show high selectivities in many chemoselective hydrogenation reactions benefitting from both capping agents and secondary metals. However, it is challenging to separately identify the role of the secondary metal and the capping agents in the bimetallic NPs because the complete removal of the capping agents can often cause their aggregation or structural/compositional changes. Herein we report the synthesis of Pt5Fex (x = 1, 2 and 4) bimetallic NPs capped by an inorganic mesoporous silica (mSiO2) shell, which could prevent NP aggregation during high-temperature treatment to remove capping agents. Using these Pt5Fex@mSiO2 NPs with a clean surface, we could demonstrate the role played independently by the bimetallic composition in the selective hydrogenation of cinnamaldehyde and furfural. Understanding the functions of the secondary metal and the surface modifying ligands on the selectivity enhancement of bimetallic NPs is necessary for the design of high-performance chemoselective catalysts.

The establishment of structure–property relationships in heterogeneous catalysis is of prime importance but remains a formidable challenge. Metal–organic frameworks (MOFs) featuring excellent chemical tunability are emerging as an auspicious platform for the atomic-level control of heterogeneous catalysis. Herein, we encapsulate palladium nanoparticles (Pd NPs) in a series of isoreticular mixed-linker MOFs, and the obtained MOF-Pd NPs catalysts were used to unveil the electronic and steric effects of linker substitution on the activity of these catalysts in the Suzuki–Miyaura cross-coupling reactions. Significantly, m-6,6′-Me2bpy-MOF-Pd exhibits a remarkable enhancement in the activity compared to non-functionalized m-bpy-MOF-Pd and m-4,4′-Me2bpy-MOF-Pd. This study unambiguously demonstrates that the stereoelectronic properties of linker units are crucial to the catalytic activity of nanoparticles encapsulated in MOFs. More interestingly, the trend of activity change is consistent with our previous work on catalytic sites generated in situ from Pd(II) coordinated in MOFs bearing the same functional groups, which suggests that both MOF-Pd NPs and MOF-Pd(II) catalysts generate similar active centers during Suzuki–Miyaura coupling reactions. This work paves a new avenue to the fabrication of advanced and tunable MOF-based catalysts through rational linker engineering. We encapsulate palladium nanoparticles in a series of isoreticular mixed-linker MOFs, and the obtained Pd-doped MOFs catalysts were used to unveil the electronic and steric effects of linker substitution on the activity of these catalysts in the context of Suzuki–Miyaura cross-coupling reactions. Impressively, m-6,6′-Me2bpy-MOF-Pd exhibits a remarkable enhancement in the activity compared to non-functionalized m-bpy-MOF-Pd and m-4,4′-Me2bpy-MOF-Pd, thus implementing atomic-level controls of heterogeneous catalysis.

The outbreak of cyanobacterial blooms has posed a huge threat to drinking water safety and the natural water environment. Among the harmful cyanobacterial bloom types, Microcystis aeruginosa is a force to be recognized with. The purpose of this work was to develop an efficient and eco-friendly technology to curb harmful cyanobacteria blooms and purify bodies of water from polluting algal organic matter. A novel and efficient electrochemical system with a graphite felt (GF) anode and Pt cathode was proposed to treat water containing M. aeruginosa, and its performance and mechanism were investigated. Without chemical consumption, the GF-Pt system with a pH widely ranging from three to nine can inactivate approximately 90% of algal cells in a short time. The ideal GF-Pt system for the removal of algal cells and Microcystin-LR operated under a pH of 7 at 75 mA, achieving removal efficiencies of 94 ± 2% and 50%, respectively. The removal mechanism was determined to be the continuous direct discharging of the anodes, with superior electro-adsorption being the key to anodization efficiency enhancement. After only flushing and drying the GF anodes before reuse, the GF-Pt system was able to maintain an algal cell removal efficiency of 83% after 10 cycles.

A metal catalyst supported on an inert substrate could consist of both metal nanoparticles and singly dispersed metal atoms. Whether these singly dispersed metal atoms are active and how different their catalytic mechanism could be in contrast to a supported metal catalyst are fundamentally important for understanding catalysis on a supported metal or oxide. By taking reduction of NO with CO on singly dispersed Rh atoms anchored on an inert support SiO2 as a probe system (Rh1/SiO2), here we demonstrated how singly dispersed metal atoms on an inert support could perform a complex multi-step catalytic cycle through a mechanism distinctly different from that for a supported metal nanoparticle with continuously packed metal sites. These singly dispersed Rh1 atoms anchored on SiO2 are active in reducing nitric oxide with carbon monoxide through two reaction pathways that are different from those of Rh nanoparticles. In situ IR studies show that a CO molecule and a NO molecule coadsorb on a singly dispersed Rh ...