Construction of Dual-Active Sites by Interfacing with Polyhydroxy Fullerene on Nickel Hydroxide Surfaces to Promote CO2 Deep Photoreduction to CH4.

Due to the complex series of elementary steps involved, achieving deep photoreduction of CO2 to multielectron products such as CH4 remains a challenging task. Therefore, it is crucial to strategically design catalysts that facilitate the controlled formation of the crucial intermediates and provide precise control over the reaction pathway. Herein, we present a pioneering approach by employing polyhydroxy fullerene (PHF) molecules to modify the surface of Ni(OH)2, creating stable and effective synergistic sites to enhance the formation of CH4 from CO2 under light irradiation. As a result, the optimized PHF-modified Ni(OH)2 cocatalyst achieves a CH4 production rate of 455 µmol g-1 h-1, with an electron-based selectivity of approximately 60%. The combination of in situ characterizations and theoretical calculations reveals that the hydroxyl species on the surface of PHF can participate in stabilizing crucial intermediates and facilitating water activation, thereby altering the reaction pathway to form CH4 instead of CO. This study provides a novel approach to regulating the selectivity of photocatalytic CO2 reduction by exploring molecular surface modification through interfacing with functionalized carbon clusters.

Molecular Co-Catalyst Confined within a Metallacage for Enhanced Photocatalytic CO2 Reduction.

The construction of structurally well-defined supramolecular hosts to accommodate catalytically active species within a cavity is a promising way to address catalyst deactivation. The resulting supramolecular catalysts can significantly improve the utilization of catalytic sites, thereby achieving a highly efficient chemical conversion. In this study, the Co-metalated phthalocyanine (Pc-Co) was successfully confined within a tetragonal prismatic metallacage, leading to the formation of a distinctive type of supramolecular photocatalyst (Pc-Co@Cage). The host-guest architecture of Pc-Co@Cage was unambiguously elucidated by single-crystal X-ray diffraction (SCXRD), NMR, and ESI-TOF-MS, revealing that the single cobalt active site can be thoroughly isolated within the space-restricted microenvironment. In addition, we found that Pc-Co@Cage can serve as a homogeneous supramolecular photocatalyst that displays high CO2 to CO conversion in aqueous media under visible light irradiation. This supramolecular photocatalyst exhibits an obvious improvement in activity (TONCO = 4175) and selectivity (SelCO = 92%) relative to the nonconfined Pc-Co catalyst (TONCO = 500, SelCO = 54%). The present strategy provided a rare example for the construction of a highly active, selective, and stable photocatalyst for CO2 reduction through a cavity-confined molecular catalyst within a discrete metallacage.

Highly Efficient and Selective Visible-Light Driven CO2 Reduction by Two Co-Based Catalysts in Aqueous Solution.

Photocatalytic CO2 reduction has been considered as a promising approach to solve energy and environmental problems. Nevertheless, developing inexpensive photocatalysts with high efficiency and selectivity remains a big challenge. In this study, two Co-based complexes [Co2(L1)Cl2] (1-Co) and [Co(L2)Cl] (2-Co) were synthesized by treating two DPA-based (DPA: dipicolylamine) ligands with Co2+, respectively. Under visible-light irradiation, the performance of 1-Co as a homogeneous photocatalyst for CO2 reduction in aqueous media has been explored by using [Ru(phen)3]2+ as a photosensitizer, and triethylolamine (TEOA) as a sacrificial reductant. 1-Co shows high photocatalytic activity for CO2-to-CO conversion, corresponding to the high TONCO of 2600 and TOFCO of 260 h-1 (TONCO = turnover number for CO; TOFCO = turnover frequency for CO). High selectivity of 97% for CO formation is also achieved. The control experiments catalyzed by 2-Co demonstrated that two Co(II) centers in 1-Co may operate independently and activate one CO2 molecule each. Furthermore, the proposed mechanism of 1-Co for photocatalytic CO2 reduction has been investigated via electrochemical analysis, a series of quenching experiments, and density functional theory calculations.

Analysis of the WHO ICTRP for novel coronavirus clinical trial registrations.

Up-to-date information on the current progress made in the research and development to control the global COVID-19 pandemic is important. The study aimed to analyze the clinical trial characteristics and vaccine development progress of the new Coronavirus Disease 2019 (COVID-19) registered with the World Health Organization International Clinical Trial Registry Platform (WHO ICTRP).A comprehensive search of COVID-19 clinical trials since the establishment of the ICTRP to June 11, 2020, was conducted to record and analyze relevant characteristics. Chi-Squared test was used to compare the statistical differences between different research types, interventions, and sources.A total of 3282 COVID-19 clinical trials in 17 clinical trial registration centers were registered with the WHO ICTRP. The main research sources for the present study were ClinicalTrials.gov and ChiCTR. There were significant differences in the parameters of study location (P = .000), number of participants (P = .000), study duration (P = .001), research stage (P = .000), randomization procedure (P = .000), and blinding method (P = .000) between the 2 registration sources. There were significant differences in all the parameters between different kinds of intervention methods. Hydroxychloroquine, plasma therapy, and Xiyanping injection were the high-frequency research drugs used. Ten different vaccine studies were registered under phases I-II.Amongst the studies researched, heterogeneity existed for various parameters. Differences in the type of study, interventions, and registration sources of the studies led to significant differences in certain parameters of the COVID-19 clinical trials. The statistics of high-frequency drugs and the progress of vaccine trials may provide an informative reference for the prevention and control of COVID-19.

Nitrogen-doped MoS2 quantum dots: Facile synthesis and application for the assay of hematin in human blood.

Nitrogen-doped MoS2 quantum dots (N-MoS2 QDs) were synthesized via a facile hydrothermal approach, and exhibited high fluorescence quantum yield (QY, 14.9%), excellent photostability, biocompatibility and water solubility. A novel method with good selectivity and sensitivity was established to assay hematin using N-MoS2 QDs as a fluorescent probe based on inner filter effect (IFE). Fluorescent quenching of N-MoS2 QDs has a fine linear dependence with the concentration of hematin in the range of 0.5-15 µmol/L and a limit of detection of 0.32 µmol/L (S/N = 3). By the detection method, average concentration of hematin in real health human erythrocytes was measured as 22.5 ± 3.9 µmol/L. And, recoveries range varied from 94 to 108% through standard recovery experiment. The N-MoS2 QDs probe shows excellent photostability, low cytotoxicity and anti-interference ability for hematin assay, which may become a promising method for the test of hematin in human blood.

Highly efficient and selective photocatalytic CO2 to CO conversion in aqueous solution.

Five molecular complexes with different non-noble metal centers were synthesized. The Co-based complex displays the highest photocatalytic performance for CO2 to CO conversion in aqueous media. It achieves high activity (TON = 41 017 and TOF = 3.80 s-1) and selectivity (87%) for the production of CO.

Gas-assisted growth of boron-doped nickel nanotube arrays: rapid synthesis, growth mechanisms, tunable magnetic properties, and super-efficient reduction of 4-nitrophenol.

Highly ordered noncrystalline boron-doped nickel nanotube arrays are rapidly synthesized within 150 s by template-based electroless deposition. The as-prepared nanotubes have tunable magnetic properties and exhibit super efficient catalytic activity (∼70 s) for the reduction of 4-nitrophenol.

Graphene oxide sheet-prussian blue nanocomposites: green synthesis and their extraordinary electrochemical properties.

A facile and green method for the synthesis of graphene oxide sheets (GOs)-prussian blue nanocomposites has been presented via a spontaneous redox reaction in a aqueous solution containing FeCl3, K3[Fe(CN)6] and graphene oxide sheets. Electrochemical property investigation demonstrates PB nanocubes formed on the surface of GOs retain their excellent electrochemical activity and the GOs can enhance the electron transfer between PB and GC electrode. Moreover, the obtained nanocomposites even have shown a higher sensitivity toward the electrocatalytical reduction of H2O2 than that of multiwalled carbon nanotube/PB nanocomposites. Given their extraordinary electrochemical properties and the green preparation, as-prepared GO-PB nanocomposites have great potential in the field of electrochemical sensor and biofuel cell.

(E)-Ethyl 3-(3-bromo-phen-yl)-2-cyano-acrylate.

The title mol-ecule, C(12)H(10)BrNO(2), adopts an E configuration with respect to the C=C bond of the acrylate unit. In the crystal structure, mol-ecules are connected by a pair of inter-molecular C-H⋯O hydrogen bonds, forming a centrosymmetric dimer.

2-(3-Methoxy-phen-yl)butane-dinitrile.

In the title compound, C(11)H(10)N(2)O, the dicyano-ethyl-ene portion has an anti conformation. The crystal structure features non-classical C-H⋯N and C-H⋯O inter-actions.

[Synthesis and spectral properties of novel C60 derivative/Ag nanocomposites].

The studies on the synthesis and properties of fullerene derivatives had been an active topic in the fullerene chemistry. So synthesis of novel fullerene derivatives and their assembly with functional nanoparticles are very meaningful. In this paper a new bipyridine-substituted [60] fullerene derivative N-methyl-2-[4'-(4"-methyl-2', 2"-bipyridinyl)]-3,4- [60] fulleropyrrolidine (C60 BPY) was synthesized by a 1,3-dipolar cycloaddition reaction with C60, 4-methyl-2,2'-bipyridine-4'-carbaldehyde and Sarcosine. Well-fined C60 BPY/Ag nanoparticles and nanostructure film were prepared by reduction method using NaBH4 as reagent and self-assembly approach with silver colloid, respectively. Transmission electronic microscope images showed that the diameters of two hybrid structures were about 30-45 nm and 40-55 nm, respectively. The nanoparticles were regular in shape with an uniform size distribution. The results indicated that C60 BPY molecule could effectively control the growth and aggregation of silver particles, and make them stable and dispersible well during the process of forming C60 BPY/Ag nanocomposites. The UV-Visible absorption spectra showed the surface plasma resonance peaks of silver nanoparticles at 430 and 490 nm in the two nanocomposites, respectively. A red shift of the plasma peak with increasing the size of the nanoparticles was also observed. The fluorescence emission peaks of C60 BPY at 720 and 805 nm were significantly quenched by the formation of the C60 BPY/Ag nanocomposites. Then the mechanism of quenching was discussed. These nanocomposites may have potential applications in optoelectrionic devices, sensors and catalysis.

Surface modification of polypropylene macroporous membrane to improve its antifouling characteristics in a submerged membrane-bioreactor: H(2)O plasma treatment.

To improve the antifouling characteristics of polypropylene hollow fiber macroporous membranes in a submerged membrane-bioreactor for wastewater treatment, the membranes were surface modified by H(2)O plasma treatment. Structural and morphological changes on the membrane surface were characterized by X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM). The change of surface wettability was monitored by contact angle measurement. The static water contact angle of the modified membrane reduced obviously with the increase of plasma treatment time. The total surface free energy and its dispersive component decreased, while the polar component increased with the increase of treatment time. The relative pure water flux for the modified membranes increased gradually with the increase of plasma treatment time. The tensile strength and the tensile elongation at break for the membranes decreased after plasma treatment. After continuous operation in a submerged membrane-bioreactor for about 68 h, flux recovery after water and caustic cleaning, flux ratio after fouling were improved by 2.0, 3.6 and 22.0%, while reduction of flux was reduced by 1.1% for the 1 min H(2)O plasma treated membrane, compared to those of the unmodified membrane.

A one-dimensional zigzag coordination polymer: catena-poly[[[triaqua-cadmium(II)]-[µ-2,2'-(5-methyl-1,3-phenyl-enedi-oxy)diacetato-κO,O':O'',O''']] monohydrate].

In the title one-dimensional coordination polymer, {[Cd(C(11)H(10)O(6))(H(2)O)(3)]·H(2)O}(n), the 2,2'-(5-methyl-1,3-phenyl-enedi-oxy)diacetate dianions connect Cd(II) ions in a head-to-tail fashion to generate zigzag chains. The coordination geometry of the Cd atom is distorted penta-gonal bipyramidal. There are O-H⋯O hydrogen bonds between the carboxyl O atoms, the aqua ligands and the uncoordinated water mol-ecules.

Surface modification of polypropylene microporous membrane to improve its antifouling characteristics in an SMBR: N2 plasma treatment.

Fouling is the major obstacle in membrane processes applied in water and wastewater treatment. The polypropylene hollow fiber microporous membranes (PPHFMMs) were surface modified by N(2) low-temperature plasma treatment to improve the antifouling characteristics. Morphological changes on the membrane surface were characterized by field emission scanning electron microscopy (FE-SEM). The change of surface wettability was monitored by contact angle measurements. The static water contact angle of the modified membrane reduced obviously; the relative pure water flux of the modified membranes increased with the increase of plasma treatment time. To assess the relation between plasma treatment and membrane fouling in a submerged membrane bioreactor (SMBR), filtration of activated sludge was carried out by using synthetic wastewater. After continuous operation in the SMBR for about 90 h, flux recoveries for the N(2) plasma-treated PPHFMM for 8 min were 62.9% and 67.8% higher than those of the virgin membrane after water and NaOH cleaning. The irreversible fouling resistance decreased after plasma treatment.

[Study on photocatalytic decomposition of azo-dyes by ZnO/carbon nanotubes composites by UV-Vis spectroscopy].

ZnO/carbon nanotubes composites were prepared by hydrothermal treatment of the mixture of zinc nitrate and acid-treated multiwalled carbon nanotubes and characterized by transmission electron microscope (TEM) and X-ray powder diffraction (XRD). The TEM image indicated that ZnO nanoparticles with a diameter about 28 nm covered the carbon nanotubes. The XRD pattern shows that ZnO nanoparticles attached to the MWNTs exhibit a hexagonal phase. The diffraction peaks can be assigned to (100), (002), (101), (102), (110), (103), (200), (112) and (201) planes of the crystalline ZnO, respectively. The average size of the crystalline ZnO, calculated from the half-width of the (100) diffraction peak by the Scherrer equation, is 27.8 nm, which accords with the TEM observation. The ZnO/carbon nanotubes composites were used as a photocatalyst under sunlight for the decomposition of azo-dye, which was studied by UV-Vis spectroscopy. The effects of the illumination time, catalyst amount, initial dye concentration and the different structures of the dye on the photocatalytic process were investigated. It was noted that the intensity of the absorption peak corresponding to the azo-dye decreased rapidly at 400 nm during the photolysis process and the decomposition of azo-dye was a quasi-first order reaction. The decomposition rates for azo-dyes such as acid orange, Acid bright red, Acid light yellow are 0.09, 0.28 and 0.22 mg x L(-1) x min(-1), respectively, which maybe resulted from their different functional groups. It can be stated that the complete removal of color, after selection of optimum operation parameters, can be achieved in relatively short time by using ZnO/carbon nanotubes composites. After recycling 5 times, the catalyst still has more than 50% efficiency.

[Microwave-assisted route to fibre-like ternary NaFeS2 nanoparticles and its XPS].

Ternary NaFeS2 nanoparticles were obtained in aqueous solution at room temperature via microwave-assisted route. The products were fibre-like with the diameter less than 10 nm, which were characterized with X-ray diffraction (XRD) pattern, transmission electron microscope (TEM) image, selected area electron diffraction (SAED) pattern and X-ray photoelectron spectroscope (XPS) pattern. The results indicated that the composition of fibre-like ternary nanoparticles are with atomic ratio of Na:Fe:S=1:1.1:1.9. The mechanism for the formation of fibre-like NaFeS2 nanoparticles is discussed.

Selective response of dopamine in the presence of ascorbic acid at multi-walled carbon nanotube modified gold electrode.

The acid-treated multi-walled carbon nanotubes (MWNTs), which were modified on the surface of gold electrode, offers substantial improvements in voltammetric sensitivity and selectivity towards the determination of dopamine (DA). It can inhibit the voltammetric response of ascorbic acid (AA) while the redox reaction of dopamine is promoted. When a differential pulse voltammetric (DPV) technique was used, the peak separation between DAs and AAs was 244 mV. Based on this, a selective method could be constructed to detect DA in the presence of 1,000 times higher concentration of AA. The effect of various experimental parameters on the voltammetric response of dopamine was investigated. Under the chosen conditions, the peak currents are correspondent linearly to the concentrations of DA in the range of 5 x 10(-7) approximately 4 x 10(-4) mol L(-1) with a limit of detection of 2 x 10(-7) mol L(-1). The proposed method can be applied to detect DA in real samples.

A reagentless biosensor of nitric oxide based on direct electron transfer process of cytochrome c on multi-walled carbon nanotube.

Direct electron transfer between Cytochrome c (Cyt.c) and electrode can be achieved through immobilizing Cyt.c on the surface of multi-walled carbon nanotubes (MWNTs). Under the condition of cyclic potential scans, Cyt.c can be adsorbed on the surface of MWNTs that were modified on a glassy carbon (GC) electrode to form an approximate monolayer. The redox characteristic and bioactivity of Cyt.c could be remained after it was adsorbed on MWNTs' surface. This provides a way to construct a new biosenser based on the activity of Cyt.c. Further investigation displayed that Cyt.c adsorbed on MWNTs showed an enzyme-like activity to catalyze the reduction of nitric oxide (NO). Due to catalyzing by Cyt.c, the reduction of NO in aqueous solution was achieved, which reductive potential appeared at -0.747V (vs. SCE). The peak currents were linearly proportional to concentration of NO in the range from 2 to 48 micromol/l with a limit of detection of 1.3 microM. The biosensor showed a good stability and excellent repeatability.

Determination of proteins with fullerol by a resonance light scattering technique.

Fullerol has been synthesized through the reaction of fullerene C60 with NaOH in aqueous solution by means of ultrasonic agitation and characterized by infrared and 1H-nuclear magnetic resonance spectroscopy. The fullerol obtained shows good solubility and excellent stability in water. A weak resonance light scattering (RLS) spectrum of fullerol was observed in aqueous solution. However, the intensity of the RLS signal could be enhanced in the presence of proteins, including bovine serum albumin (BSA), human serum albumin (HSA), pepsin (Pep), and lysozyme (Lys). Based on the enhancement of the RLS, a sensitive method for the determination of proteins has been established. The quantitative conditions were considered with regard to the effects of the pH, the ion strength, and the concentration of the fullerol. Under the optimum conditions, the intensity of the RLS was proportional to the concentration of proteins with the limits of detection of 9.7, 10.9, 57.4, and 8.5 ng mL(-1) for BSA, HSA, Pep, and Lys, respectively. Almost no interference can be observed from some amino acids, nucleic acids, and most of the metal ions. The model samples and human serum samples were determined satisfactorily with the proposed method.