NiSe2/CeO2 catalysts from Ce-UiO-66 metal-organic skeletons and their electrocatalytic oxidation of methanol, urea and glycerol.

Hydrogen is a viable alternative energy source to fossil fuels. In order to manufacture enough hydrogen to meet the needs of social growth, finding an alternate energy source that is more effective is essential. Electrochemical water cracking is a more appropriate method for producing hydrogen. The methanol oxidation reaction (MOR), urea oxidation reaction (UOR) and glycerol oxidation reaction (GOR) can be used to replace the anodic oxygen evolution reaction (OER) and indirectly accelerate the hydrogen evolution reaction (HER), which has the advantages of saving energy and reducing environmental pollution. In this study, Ni/CeO2 catalysts were prepared by thermal annealing of MOFs (Ce-UiO-66) containing nickel species and NiSe2/CeO2 nanocrystalline catalysts were obtained through the selenation reaction at different temperatures. The NiSe2/CeO2-450 °C catalysts exhibited superior catalytic performance for the MOR, UOR, and GOR. The MOR showed a peak current density of roughly 186.68 mA cm-2 and a low oxidation potential of around 1.34 V. Similarly, the UOR demonstrated a peak current density of approximately 142.28 mA cm-2 and a low oxidation potential of around 1.32 V. Furthermore, the GOR exhibited a peak current density of approximately 82.56 mA cm-2 and a low oxidation potential of around 1.37 V. NiSe2/CeO2-450 °C could improve electrocatalytic performance for the MOR, UOR, and GOR, which is attributed to the more active sites that were exposed as a result of utilizing MOFs (Ce-UiO-66) as a precursor. Additionally, selenation increased the ability to transfer electrons. This research is crucial for the production of inexpensive, easily accessible transition metals in place of expensive noble metals, for the reduction of wastewater pollution from methanol and urea, and for the creation of effective anodic oxidation electrocatalysts.

Understanding the copper-iridium nanocrystals as highly effective bifunctional pH-universal electrocatalysts for water splitting.

It is pivotal to develop an economical, effective, and stable catalyst to promote the oxygen/hydrogen evolution reaction (OER/HER) throughout pH electrolytes, as the demand for hydrogen energy will increase greatly with the future development. Herein, a series of Ir-Cu nanoparticle composite carbon (IrxCuy/C) catalysts are successfully synthesized using ethylene glycol reduction. In addition, the structure, morphology and composition of the electrocatalysts were systematically characterized, and the OER/HER performance of the catalysts was also tested under different pH conditions. According to experimental findings, amorphous Ir3Cu/C has superior competent performance to catalyze oxygen (O2) production in alkaline and acidic environments. The comparatively low overpotentials required are 222 mV and 304 mV, respectively, while generating a current density of 10 mA cm-2. The reduced amount of precious metal and the further improvement in activity and durability make Ir3Cu/C an excellent noble metal-based electrocatalyst. Meanwhile, IrCu/C has significant electrocatalytic performance for the HER in acidic media.

Preparation of 3D Nd2O3-NiSe-Modified Nitrogen-Doped Carbon and Its Electrocatalytic Oxidation of Methanol and Urea.

Developing renewable energy sources and controlling water pollution are critical but challenging problems. Urea oxidation (UOR) and methanol oxidation (MOR), both of which have high research value, have the potential to effectively address wastewater pollution and energy crisis problems. A three-dimensional neodymium-dioxide/nickel-selenide-modified nitrogen-doped carbon nanosheet (Nd2O3-NiSe-NC) catalyst is prepared in this study by using mixed freeze-drying, salt-template-assisted technology, and high-temperature pyrolysis. The Nd2O3-NiSe-NC electrode showed good catalytic activity for MOR (peak current density ~145.04 mA cm-2 and low oxidation potential ~1.33 V) and UOR (peak current density ~100.68 mA cm-2 and low oxidation potential ~1.32 V); the catalyst has excellent MOR and UOR characteristics. The electrochemical reaction activity and the electron transfer rate increased because of selenide and carbon doping. Moreover, the synergistic action of neodymium oxide doping, nickel selenide, and the oxygen vacancy generated at the interface can adjust the electronic structure. The doping of rare-earth-metal oxides can also effectively adjust the electronic density of nickel selenide, allowing it to act as a cocatalyst, thus improving the catalytic activity in the UOR and MOR processes. The optimal UOR and MOR properties are achieved by adjusting the catalyst ratio and carbonization temperature. This experiment presents a straightforward synthetic method for creating a new rare-earth-based composite catalyst.

Porous Electrospun Films with Reversible Photoresponsive Microenvironmental Humidity Regulation: A Controllable Hydrogen-Bonding Synergistic Effect Exhibited by Acrylic Acid Segments.

Suitable relative humidity is essential for the preservation of cultural relics, food storage, and so on. A special material that can regulate the relative humidity in the microenvironment is particularly important. In this work, several innovative electrospun films with reversible photoresponsive wettability and the ability to regulate microenvironmental relative humidity were prepared. The spiropyran unit of the synthesized copolymer played the most important role in humidity regulation due to its reversible transition between a nonpolar ring-closed state and a polar ring-opened state induced by alternating ultraviolet/visible illumination. More interestingly, the introduction of acrylic acid segments exhibited a controllable hydrogen bond synergistic effect for increasing the range of humidity regulation. The color change and the reversible change ranges of wettability and microenvironmental relative humidity under ultraviolet/visible irradiation are all closely related to the number of acrylic acid segments. Cassie theory, density functional theory (DFT), and interaction region indicator (IRI) analysis were used to characterize this phenomenon. Electrospinning is a promising method to achieve large-scale production that can put such material into practical applications.

Revealing the Real Role of Etching during Controlled Assembly of Nanocrystals Applied to Electrochemical Reduction of CO2.

In recent years, the use of inexpensive and efficient catalysts for the electrocatalytic CO2 reduction reaction (CO2RR) to regulate syngas ratios has become a hot research topic. Here, a series of nitrogen-doped iron carbide catalysts loaded onto reduced graphene oxide (N-Fe3C/rGO-H) were prepared by pyrolysis of iron oleate, etching, and nitrogen-doped carbonization. The main products of the N-Fe3C/rGO-H electrocatalytic reduction of CO2 are CO and H2, when tested in a 0.5 M KHCO3 electrolyte at room temperature and pressure. In the prepared catalysts, the high selectivity (the Faraday efficiency of CO was 40.8%, at -0.3 V), and the total current density reaches ~29.1 mA/cm2 at -1.0 V as demonstrated when the mass ratio of Fe3O4 NPs to rGO was equal to 100, the nitrogen doping temperature was 800 °C and the ratio of syngas during the reduction process was controlled by the applied potential (-0.2~-1.0 V) in the range of 1 to 20. This study provides an opportunity to develop nonprecious metals for the electrocatalytic CO2 reduction reaction preparation of synthesis and gas provides a good reference.

Water-Tolerant Boron-Substituted MCM-41 for Oxidative Dehydrogenation of Propane.

Boron-based catalysts for oxidative dehydrogenation of propane (ODHP) have displayed excellent olefin selectivity. However, the drawback of deboronation leading to catalyst deactivation limited their scalable applications. Hereby, a series of mesoporous B-MCM-41 (BM-x, B/Si = 0.015-0.147) catalysts for ODHP were prepared by a simple hydrothermal synthesis method. It was found that propane conversion was increased and the initial reaction temperature was reduced with an increase of boron content, and the optimal values appeared on BM-2.0 (B/Si = 0.062), while olefins' (ethylene and propylene) selectivity was maintained at ca. 70-80%. Most importantly, BM-1.0 (B/Si = 0.048) exhibited favorable activity, stability, and water tolerance after washing treatment or long-time operation (e.g., propane conversion of ca. 15% and overall olefin selectivity of ca. 80% at 550 °C) because its high structural stability prevented boron leaches. These features were identified by X-ray diffraction (XRD), N2 physisorption, inductively coupled plasma-mass spectrometry (ICP-MS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and solid-state magic-angle-spinning nuclear magnetic resonance (MAS NMR) spectroscopy studies. The tri-coordinated B-OH species incorporated into the mesoporous silica framework are considered to be the active sites for ODHP.

Controlled assembly of nitrogen-doped iron carbide nanoparticles on reduced graphene oxide for electrochemical reduction of carbon dioxide to syngas.

The electrocatalytic CO2 reduction reaction (CO2RR) decreases the amount of greenhouse gas in the atmosphere while enabling a closed carbon cycle. Herein, iron oleate was used as a precursor to produce oleic acid-coated triiron tetraoxide nanoparticles (Fe3O4@OA NPs) by pyrolysis, which was then assembled with reduced graphene oxide (rGO) and doped with dicyandiamide as a nitrogen source to obtain nitrogen-doped iron carbide nanoparticles assembled on rGO (N-Fe3C/rGO NPs). The catalyst prepared by nitrogen doping at 800 °C with an Fe3O4@OA NPs to rGO weight ratio of 20:1 showed good activity and stability for the CO2RR. At -0.3 to -0.4 V, the H2/CO ratio of the product from the catalyzed CO2RR was close to 2; thus, the product can be used for Fischer-Tropsch synthesis. The results of a series of experiments and X-ray photoelectron spectroscopy analysis showed that the synergy between the CN and FeN groups in the catalyst can promote the reduction of CO2 to CO. This work demonstrates a facile method for improving the catalytic reduction of CO2.

Ultradispersed Ir x Ni clusters as bifunctional electrocatalysts for high-efficiency water splitting in acid electrolytes.

Design and synthesis of electrocatalysts with high activity and low cost is an important challenge for water splitting. We report a rapid and facile synthetic route to obtain Ir x Ni clusters via polyol reduction. The Ir x Ni clusters show excellent activity for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic electrolytes. The optimized Ir2Ni/C clusters exhibit an electrochemical active area of 18.27 mF cm-2, with the overpotential of OER being 292 mV and HER being 30 mV at 10 mA cm-2, respectively. In addition, the Ir2Ni/C used as the cathode and anode for the H-type hydrolysis tank only needs 1.597 V cell voltages. The excellent electrocatalytic performance is mainly attributed to the synergistic effect between the metals and the ultra-fine particle size. This study provides a novel strategy that has a broad application for water splitting.

Rational design of Cu3PdN nanocrystals for selective electroreduction of carbon dioxide to formic acid.

The selective electrochemical reduction of CO2 yields value-added products that are important renewable energy resources for carbon recycling. In this study, Cu3PdN nanocrystals (NCs) exhibited higher electrocatalytic activity for carbon dioxide (CO2) reduction to formic acid (HCOOH) than as-prepared Cu3N and Cu3Pd NCs. In addition, the reaction yielded small amounts of CO (<5%), H2, and HCOOH as the main products, and the electrocatalytic activity of the Cu NCs was significantly enhanced by modification with N and Pd. This work demonstrates a simple and effective strategy for improving the electrochemical reduction of CO2.

One pot synthesis of diarylfurans from aryl esters and PhI(OAc)2 via palladium-associated iodonium ylides.

The example of palladium-catalyzed intermolecular cyclization for the synthesis of various diarylfurans in which one of the aromatic rings originates from the phenolic part of the starting ester and the other one from PhI(OAc)2 has been reported. The reaction is carried out through two steps: the rearrangement of palladium-associated iodonium ylides to form o-iodo diaryl ether and then palladium catalyzed intramolecular direct arylation. This reaction can tolerate a variety of functional groups and is alternative or complementary to the previous methods for the synthesis of diarylfurans.

Energy-efficient green catalysis: supported gold nanoparticle-catalyzed aminolysis of esters with inert tertiary amines by C-O and C-N bond activations.

Catalyzed by supported gold nanoparticles, an aminolysis reaction between various aryl esters and inert tertiary amines by C-O and C-N bond activations has been developed for the selective synthesis of tertiary amides. Comparison studies indicated that the gold nanoparticles could perform energy-efficient green catalysis at room temperature, whereas Pd(OAc)2 could not.

Aminolysis of aryl ester using tertiary amine as amino donor via C-O and C-N bond activations.

An aminolysis reaction between various aryl esters and inert tertiary amines by C-O and C-N bond activations has been developed for the selective synthesis of a broad scope of tertiary amides under neutral and mild conditions. The mechanism may undergo the two key steps of oxidative addition of acyl C-O bond in parent ester and C-N bond cleavage of tertiary amine via an iminium-type intermediate.

[Active oxygen species of Co-V-O catalysts in propane oxidative dehydrogenation analyzed by FTIR and XPS spectra].

A series of Co-V-O (meta-CoV2O6, pyro-Co2 V2 O7, and ortho-Co3 V2 O8) catalysts were prepared by microwave oxalate co-precipitation method and characterized by (XRD), TEM, BET, FTIR, XPS, H2-TPR and conductivity measurement. The catalytic characters of the catalysts for propane oxidative dehydrogenation were investigated. The FTIR spectra of catalysts were obtained in the range of 400-1 100 cm(-1) and their major bands were assigned. The peak separation fitting of O(1s) XPS spectra was carried out and the quantity of oxygen species was calculated. The results of XRD characterization showed that pure meta-CoV2O6, pyro-Co2 V2O7, and ortho-Co3 V2O8 with nice structure were obtained. The TEM images demonstrated that the catalysts showed uniform particle with the mean particle size of 20-30 nm. The diagram of the relationship between electrical conductivity and oxygen partial pressure of Co3V2O8 and Co2 V2O7 showed dsigma/dPo2 > 0, which implied that these were p-type semiconductor, and CoV2O6 reverse showed dsigma/dPo2 < 0, which implied n-type semiconductor. 48.12%, 47.82% and 35.24% of C3 H6 selectivities were obtained for p-type semiconductor Co3 V2O8, CO2 V2O7 and n-type CoV2O6 catalysts respectively at 10% C3H6 conversion, and the results showed that p-type semiconductor catalysts Co3 V2O8 and Co2 V2O7 showed higher activity than n-type catalyst CoV2O6. The results of FTIR, XPS, H2-TPR and conductivity measurement indicated that transferring between non-stoichiometric and lattice oxygen that easily happened in Co3 V2O8 and Co2 V2O7 catalysts might promote the oxidation-reduction reaction between different valence vanadium species, and promoted the oxygen vacancy formation. Furthermore, the forming of Co-O-V bridge bond that was easy to shift between Co and V increased the mobile oxygen species of O2-, O2(2-) and O- and made the redox reaction among different valence V be realized. It is concluded that high catalytic properties of p-type semiconductor Co3 V2O8 and Co2 V2O7 can be attributed to the abundant oxygen species O- that existed in these catalysts.

[Determination of trace elements in mongolian medicine curing hyperlipidemia disease by ICP-AES].

During the study of the Mongolian medicine, we found that the Mongolian medicine contains great amount and a variety of trace elements needed for human body, but the heavy metals are very little. A method for the determination of Ca, Cu, Zn, Fe, Mg, Mn and Pb in the Mongolian medicine. (1# the morning medicine, 2# the noon medicine and 3# the evening medicine.) by ICP-AES with microwave, digestion was studied. The recoveries of standard addition are in the range of 94.63%-106.40%. The relative standard deviation is < or = 3.41, and detection limit is in the range of < or = 0.009 microg x L(-1). The results show that 1#, 2# and 3# are different kinds of medicine with some difference in the trace elements quantity, but can cure hyperlipidemia disease by their combination.

[Study on performance of Ni3 V2O8 catalyst and analysis of X-ray photoelectron spectroscopy].

Ni3V2O8 catalyst was prepared by oxalate co-precipitation method with microwave heating in this paper. In order to study the relationship between the catalytic performance and the surface species, the catalyst was characterized by XRD, BET, H2-TPR, XPS, TEM and conductivity measurement. The surface property of Ni3V2O8 was studied by XPS and the catalytic performance of the oxidative dehydrogenation of propane to propylene was also investigated. The results of XRD showedthat pure Ni3V2O8 with nice structure was obtained. TEM experiments results demonstrated that the prepared Ni3V2O8 catalyst at 700 degrees C calcination showed uniform particle with the mean particle size of 30 nm. The surface area of the catalyst was 8.623 m2 x g(-1). The diagram of the relationship between electrical conductivity and oxygen partial pressure of Ni3V2O8 showed dsigma/dPO2, >0, implying that Ni3V2O8 catalyst was a p-type semiconductor. H2-TPR results showed that only one unsymmetrical reduction peak appeared at 663.5 degreesC within 300-900 degrees C region over Ni3V2O8 catalyst and no obvious shoulder peak was observed. It could also be found that the ratio of non complete reduction oxygen species was about 33.59% (O(-) 27.55%, O2(2-) 6.04%) from the O(1s) XPS result and more V4+ species existed on the Ni3V2O8 catalyst surface. The TPR and XPS results illustrated that the transformation of the lattice oxygen to non-complete reduction oxygen in NiV2O8 catalyst might promote the oxidation-reduction reaction between different valence vanadium and promoted the oxygen vacancy formation. This then led to abundant non-complete reduction oxygen O(-) and V4+ species formation on the surface of Ni3V2O8 catalyst. The active result of oxidative dehydrogenation of propane to propylene showed that the 60.02% propylene selectivity could be reached at 18.60% propane conversion. Compared with the reported results over the coexistent NiO and Ni3V2O8 system from the literature, pure Ni3V2O8 catalyst system in this present paper showed higher propylene selectivity than the coexistent NiO and Ni3V2O8 system under the same propane conversion condition, suggesting that the performance of propane to propene is correlated to the oxidation-reduction of V4+ / V5+ couple and non complete reduction oxygen species (O(-) or O2(2-)). This result further illustrated that NiV2O8 was active phase for oxidative dehydrogenation of propane to propylene. Combining the active and characterization results, it was found that catalytic activity was correlated to the surface non-complete reduction O(-) and V4+ species, which was beneficial to improving the propylene selectivity.

Effect of Maotai liquor in inducing metallothioneins and on hepatic stellate cells.

AIM: To explore the possible mechanism why drinking Maotai liquor dose not cause hepatic fibrosis. METHODS: After being fed with Maotai for 56 days consecutively, the male SD rats were decollated for detecting the biological indexes, and the livers were harvested to examine the liver indexes and the level of hepatic metallothioneins (MT). Hepatic stellate cells (HSC) proliferation and collagen generation were also observed. RESULTS: Hepatic MT contents were 216.0 ng.g(-1)+/-10.8 ng.g(-1) in the rats of Maotai group and 10.0 ng.g(-1)+/-2.8 ng.g(-1) in the normal control group, which was increased obviously in Maotain group (P<0.05). In the rats with grade CCL(2) poisoning induced by Maotai, hepatic MT content was 304.8 ng.g(-1)+/-12.1 ng.g(-1) whereas in the controls with grade CCL(4) poisoning, it was 126.4 ng.g(-1)+/-4.8 ng.g(-1) (P<0.05). MDA was 102.0 nmol.g(-1)+/-3.4 nmol.g(-1) in Maotai group and 150.8 nmol.g(-1)+/-6.7 nmol.g(-1) in the control group (P<0.05). When both of the groups were suffering from grade CCL(4) poisoning, hepatic MT contents was negatively correlated with MDA (r=-0.8023, n=20, P<0.01). The 570 nmA values of each tube with HSC regeneration at concentrations of 0, 10, 50, 100, and 200 g.L(-1) of Maotai were 0.818, 0.742, 0.736, 0.72, 0.682, and 0.604, respectively. From the concentration of 10 g.L(-1), Maotai began to show obvious inhibitory effects against HSC, and the inhibition was concentration-dependent (P<0.05, P<0.01). Type I collagen contents in HSC were 61.4, 59.9, 50.1, 49.2, 48.7, 34.4 microg.g(-1) at concentrations of 0, 10, 50, 100, and 200 g.L(-1) of Maotai. At the concentration of 100-200 g.L(-1), Maotai had obvious inhibitory effect against the secretion of type I collagen (P<0.05). Gene expression analysis was conducted on cells with Maotai concentrations of 0, 50, 100g.L(-1) respectively and the ash values of beta-actin gene expression were 0.88, 0.74, and 0.59, respectively,suggesting that at the concentration of 100g.L(-1), Maotai could obviously inhibit gene expression of type I procollagen (P<0.05), but the effect was not obvious at the concentration of 50 g.L(-1) (P>0.05). At the concentration of 10 g.L(-1), HSC growth in vitro inhibition rates were 16.4+/-2.3 in Maotai group and -8.4+/-2.3 in the control group (P<0.05). CONCLUSION: Maotai liquor can increase metallothioneins in the liver and inhibit the activation of HSC and the synthesis of collagen in many aspects, which might be the mechanism that Maotai liquor interferes in the hepatic fibrosis.