Fabrication of Gelatin-Derived Gel Electrolyte Using Deep Eutectic Solvents through In Situ Derivatization and Crosslinking Strategy for Supercapacitors and Flexible Sensors.

The facile fabrication of gel polymer electrolytes is crucial to the development of flexible electronics, and the use of natural polymers as sources has obtained great attention due to their abundant, low-cost, biodegradable, easy modification, and biocompatible features. In this article, a facile fabrication protocol to engineer gelatin into gel electrolytes was developed by taking the advantages of both deep eutectic solvent (DES) (including its good solubility to gelatin and satisfactory electrochemical properties) and rich active functional groups of gelatin, through in situ derivatization and crosslinking strategy. A double-crosslinked DES gel electrolyte was prepared with the dissolution of gelatin in choline chloride and alcohol-based DES and a further crosslinking with Fe3+ ions. The obtained DES gel presented outstanding mechanical properties, excellent ionic conductivity (up to 101-102 mS/cm), a wide operating temperature range (-40 to 80 °C), satisfactory self-healing property, and good degradability. Moreover, the obtained DES gel electrolyte was successfully applied to supercapacitors and flexible sensors, showing excellent electrochemical performance and strain-response properties. In a word, our study provides a facile protocol to engineer gelatin into gel electrolytes by using deep eutectic solvent, showing significant insights into the design and preparation of sustainable gel polymer electrolytes and having great application potential in next-generation high-performance flexible electronics.

Noble-metal-free Co-N-C catalyst derived from cellulose-based poly(ionic liquid)s for highly efficient oxygen reduction reaction.

Noble-Metal-Free nitrogen-doped carbon-based materials are promising electrocatalysts for oxygen reduction reaction (ORR), yet it remains a great challenge to construct efficient porous non-noble metal nitrogen-doped carbon (M-N-C) catalysts with uniform distribution, due to the easy aggregation of metals. Herein, we reported the synthesis and assessment of a novel and efficient noble-metal-free catalyst for oxygen reduction reaction (ORR) from pyrolysis of a cobalt-containing cellulosic poly(ionic liquid) (Co-N-C). The prepared Co-N-C catalyst possesses high surface area, hierarchical porous structure, well-dispersed Co nanoparticles and large amounts of low-coordinated Co active sites. Especially, the Co-N-C-850 sample exhibits a high ORR activity (Eonset = 0.827 V, E1/2 = 0.74 V) that can rival 20 wt% commercial Pt/C (Eonset = 0.833 V, E1/2 = 0.71 V) in alkaline media. Moreover, the Co-N-C-850 sample also shows excellent anti-methanol poisoning activity and long-term stability toward ORR compared with commercial Pt/C. Our study provides a promising avenue both for the development of non-noble M-N-C catalysts for fuel cells and the functional utilization of cellulose.

Super-stable mineralization of Cu, Cd, Zn and Pb by CaAl-layered double hydroxide: Performance, mechanism, and large-scale application in agriculture soil remediation.

The synthesized CaAl-layered double hydroxide (CaAl-LDH) shows excellent performance in potentially toxic metals (PTMs) removal, and the removal capacity of CaAl-LDH toward Cu2+, Zn2+ and Pb2+ in aqueous solution is 502.4, 315.2 and 600.0 mg/g respectively. Cu2+ and Zn2+ are removed through isomorphic substitution of laminate Ca and dissolution-reprecipitation, leading to the formation of CuAl-LDH and ZnAl-LDH mineralization products. Pb2+ is removed by the complexation and precipitation to form Pb3(CO3)2(OH)2. The application of CaAl-LDH in laboratory-scale soil remediation shows that target PTMs are gradually mineralized into relatively stable oxidizable and residual state, and the immobilization efficiency of available Cu, Zn, Cd and Pb reaches 84.62 %, 98.66 %, 96.81 % and 70.27 % respectively. In addition, practical application in farmland results in the significant reduction of available Cu, Zn, Cd and Pb with the immobilization efficiency of 30.15 %, 67.30 % and 57.80 % and 38.71 % respectively. Owing to the super-stable mineralization effect of CaAl-LDH, the content of PTMs in the roots, stems and grains of cultivated buckwheat also decreases obviously, and the growth and yield of buckwheat are not adversely affected but improved. The above prove that the super-stable mineralization based on CaAl-LDH is a promising scheme for the remediation of PTMs contaminated agriculture soil.

A high-performance Cu-Al dual-ion battery realized by high-concentration Cl- electrolyte and CuS cathode.

We propose a new Cu-Al dual-ion battery that aqueous solution composed of LiCl, CuCl and AlCl3 (LiCuAl) is used as the electrolyte, CuS is used as the cathode of aqueous aluminum ion battery for the first time and copper foil is used as the anode. The assembled Cu-Al dual-ion battery yields a reversible capacity of 538 mA h/g at 200 mA/g, and exhibits longterm cycling stability of over 200 cycles with 88.6% capacity retention at 1000 mA/g. Above excellent performance is inseparable from the three components of LiCuAl electrolyte and electrode materials. The Al-storage mechanism of CuS is proposed that the S-S bond in CuS lattice interacts with aluminum ions during the aluminum storage process. In addition, the charging and discharging process does not cause irreversible damage to the S-S bond, thus Cu-Al dual-ion battery with CuS as cathode shows great cycle stability.

Activated MoS2 by Constructing Single Atomic Cation Vacancies for Accelerated Hydrogen Evolution Reaction.

Regulating the electronic structure of MoS2 by constructing cationic vacancies is an effective method to activate and improve its intrinsic properties. Herein, we synthesize the MoS2-based composite with abundant single atomic Mo cation vacancies through uniformly loading nickel-cobalt-Prussian blue analogues (NiCoPBA) (NiCoPBA-MoS2-VMo) by immersing a single Ni atom-decorated MoS2 (Ni-MoS2) into K3[Co(CN)6] solution. Subsequently, NiCoP-MoS2-VMo with improved conductivity is obtained by phosphating the composite as a high-efficiency hydrogen evolution reaction (HER) catalyst. Experiments and theoretical calculations indicate that the electrons of NiCoP are spontaneously transferred to the substrate MoS2-VMo nanosheets in NiCoP-MoS2-VMo, and the moderately oxidized NiCoP is beneficial to the adsorption of OH*. Meanwhile, the mono-atomic Mo cation vacancies of the catalyst modulate the electronic structure of S, optimizing the adsorption of hydrogen in the reaction process. Therefore, NiCoP-MoS2-VMo has enhanced chemical adsorption for H* (on MoS2-VMo) and OH*(on NiCoP), expediting the water-splitting step and HER catalysis, and benefiting from the regulation of the electronic structure induced by the construction of metallic Mo vacancies in MoS2, the as-prepared catalyst displays an overpotential of only 67 mV at 10 mA cm-2 with long-term stability (no current decay over 20 h). This work affords not only a kind of efficient HER catalysts but also a new valuable route for developing inexpensive and high-performance catalysts with single atomic cation vacancies.

Enhanced improvement of soda saline-alkali soil by in-situ formation of super-stable mineralization structure based on CaFe layered double hydroxide and its large-scale application.

In-situ super-stable mineralization technology with mineralizers (CaSO4, Fe2(SO4)3) and attapulgite (ATP) clay were applied to improve soda saline-alkali soil. The addition of mineralizers and the existence of OH and CO32- in soil resulted in the formation of CaFe-layered double hydroxide (CaFe-LDH) with super-stable mineralization structure (Ksp = 1.512 × 10-61), which was confirmed by the characterization of physicochemical properties and density functional theory (DFT) calculation. The fixation of OH- and CO32- during the formation process of CaFe-LDH led to the transformation of the existing forms of OH- and CO32- in soil from free to stable state, resulting in the permanent decrease of soil pH and CO32- concentration. The effect of ATP clay on the decrease of soluble Na ions in soil through electrostatic attraction and cation exchange was also indicated. Furthermore, mineralizers (1.2 t/ha CaSO4 and 0.75 t/ha Fe2(SO4)3) and ATP clay (1.2 t/ha) were applied to 1.33 ha soda saline-alkali land, and Rumex patientia L. was seeded meanwhile for the identification of improved performance. After five months of improvement, the physical and chemical properties of soil were improved that pH, electrical conductivity (EC), the concentration of CO32- and soluble Na ions, and soil bulk density decreased significantly. In addition, the emergence rate of Rumex patientia L. increased from 0% to 98.3%. All above indicated that in-situ super-stable mineralization technology with the properties of high efficiency, long-term and cost-effective (234.88 $/ha) displays excellent potential in the improvement of soda saline-alkali soil.

Acid-Etched Co3O4 Nanoparticles on Nickel Foam: The Highly Reactive (311) Facet and Enriched Defects for Boosting Methanol Oxidation Electrocatalysis.

The confirmation and regulation of active sites are particularly critical for the design of methanol oxidation reaction (MOR) catalysts. Here, an acid etching method for facet control combined with defect construction was utilized to synthesize Co3O4 nanoparticles on nickel foam for preferentially exposing the (311) facet with enriched oxygen vacancies (VO). The acid-leached oxides exhibited superior MOR activity with a mass activity of 710.94 mA mg-1 and an area-specific activity of 3.390 mA cm-2 as a result of (i) abundant active sites for MOR promoted by VO along with the highly active (311) facet being exposed and (ii) phase purification-reduced adsorption energy (Eads) of methanol molecules. Ex situ X-ray photoelectron spectroscopy proved that highly active CoOOH obtained via the activation of plentiful Co2+ effectively improved the MOR. Density functional theory calculations confirmed that the selective exposed (311) facet has the lowest Eads for CH3OH molecules. This work puts forward acid etching as the facet modification and defect engineer for nanostructured non-noble catalysts, which is expected to result in superior electrochemical performance required for advanced alkaline direct methanol fuel cells.

Heterostructure Ni3S4-MoS2 with interfacial electron redistribution used for enhancing hydrogen evolution.

Developing highly effective and inexpensive electrocatalysts for hydrogen evolution reaction (HER), particularly in a water-alkaline electrolyzer, are crucial to large-scale industrialization. The earth-abundant molybdenum disulfide (MoS2) is an ideal electrocatalyst in acidic media but suffers from a high overpotential in alkaline solution. Herein, nanospherical heterostructure Ni3S4-MoS2 was obtained via a one-pot synthesis method, in which Ni3S4 was uniformly integrated with MoS2 ultrathin nanosheets. There were abundant heterojunctions in the as-synthesized catalyst, which were verified by X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). The structure features with interfacial electron redistribution was proved by XPS and density functional theory (DFT) calculations, which offered several advantages to promote the HER activity of MoS2, including increased specific surface area, exposed abundant active edge sites and improved electron transfer. Ni3S4-MoS2 exhibited a low overpotential of 116 mV at 10 mA cm-2 in an alkaline solution with a corresponding Tafel slope of 81 mV dec-1 and long-term stability of over 20 h. DFT simulations indicated that the synergistic effects in the system with the chemisorption of H on the (002) plane of MoS2 and OH on the (311) plane of Ni3S4 accelerated the rate-determining water dissociation steps of HER. This study provides a valuable route for the design and synthesis of inexpensive and efficient HER electrocatalyst, heterostructure Ni3S4-MoS2.

Iron-containing palygorskite clay as Fenton reagent for the catalytic degradation of phenol in water.

Heterogeneous Fenton systems have great application prospects in the catalytic degradation of organic wastewater; however, they are still not widely used in operation due to the difficulty of preparing catalysts in low yields and the high manufacturing cost. Herein, we report that a pristine iron-containing palygorskite clay can be used as a Fenton catalyst reagent without any retreatment. The composition, morphology, and structure of palygorskite clay, as well as the distribution and content of Fe element in palygorskite, were characterized via several physicochemical techniques. The degradation reaction of phenol in water was carried out as a probe reaction for the palygorskite Fenton reagent. The effects of the palygorskite content, pH value, and hydrogen peroxide concentration on the degradation efficiency of phenol were studied. Under optimum operating conditions, the chemical oxygen demand (COD) degradation efficiency of phenol reaches 94% with a reaction temperature of 20 °C and a reaction time of 15 min.

The Principle of Introducing Halogen Ions Into ß-FeOOH: Controlling Electronic Structure and Electrochemical Performance.

Coordination tuning electronic structure of host materials is a quite effective strategy for activating and improving the intrinsic properties. Herein, halogen anion (X-)-incorporated ß-FeOOH (ß-FeOOH(X), X = F-, Cl-, and Br-) was investigated with a spontaneous adsorption process, which realized a great improvement of supercapacitor performances by adjusting the coordination geometry. Experiments coupled with theoretical calculations demonstrated that the change of Fe-O bond length and structural distortion of ß-FeOOH, which is rooted in halogen ions embedment, led to the relatively narrow band gap. Because of the strong electronegativity of X-, the Fe element in ß-FeOOH(X)s presented the unexpected high valence state (3 + δ), which is facilitating to adsorb SO32- species. Consequently, the designed ß-FeOOH(X)s exhibited the good electric conductivity and enhanced the contact between electrode and electrolyte. When used as a negative electrode, the ß-FeOOH(F) showed the excellent specific capacity of 391.9 F g-1 at 1 A g-1 current density, almost tenfold improvement compared with initial ß-FeOOH, with the superior rate capacity and cyclic stability. This combinational design principle of electronic structure and electrochemical performances provides a promising way to develop advanced electrode materials for supercapacitor.

A hierarchical Nb2O5@NiFe-MMO rod array, fabricated and used as a structured photocatalyst.

Recently, using sunlight as a driving force with transitional metal oxides as photocatalysts, due to their unique optical and catalytic properties for organic reactions, has been considered to be a promising strategy in synthetic chemistry. Here, a hierarchically structured photocatalyst, a NiFe mixed metal oxide coated Nb2O5 (denoted as Nb2O5@NiFe-MMO) rod array has been successfully fabricated using Nb foil as a substrate. The Nb2O5 rod array was synthesized by the oxidative etching of Nb metal on the surface of the a substrate. The coating NiFe-MMO was obtained by the calcination of a NiFe layered double hydroxide (NiFe-LDH) precursor via the in situ epitaxial growing technique. The Nb2O5@NiFe-MMO rod array extended the photoresponse light region from ultraviolet light around 400 nm to visible light around 600 nm. With the well-designed architecture and highly dispersed NiO and Fe2O3, the as-prepared photocatalyst exhibited excellent activity and recyclability toward the reaction of aerobic coupling under relatively green conditions, with catalytic efficiency of 228 µmol cm-2 (the area is that of the Ni foil substrate) at 30 °C for 5 h. The present work provides a new strategy for the exploration of excellent structured photocatalysts based on transition metal oxide materials for selective aerobic oxidation of benzylamine to imine.

Solid-Solution Sulfides Derived from Tunable Layered Double Hydroxide Precursors/Graphene Aerogel for Pseudocapacitors and Sodium-Ion Batteries.

Transition-metal sulfides (TMSs) are suggested as promising electrode materials for electrochemical pseudocapacitors and lithium- and sodium-ion batteries; however, they typically involve mixed composites or conventionally stoichiometric TMSs (such as NiCo2S4 and Ni2CoS4). Herein we demonstrate a preparation of solid-solution sulfide (Ni0.7Co0.3)S2 supported on three-dimensional graphene aerogel (3DGA) via a sulfuration of NiCo-layered double hydroxide (NiCo-LDH) precursor/3DGA. The electrochemical tests show that the (Ni0.7Co0.3)S2/3DGA electrode exhibits a capacitance of 2165 F g-1 at 1 A g-1, 2055 F g-1 at 2 A g-1, and 1478 F g-1 at 10 A g-1; preserves 78.5% capacitance retention upon 1000 cycles for pseudocapacitors; and in particular, possesses a relatively high charge capacity of 388.7 mA h g-1 after 50 cycles at 100 mA g-1 as anode nanomaterials for sodium-ion batteries. Furthermore, the electrochemical performances are readily tuned by varying the cationic type of the tunable LDH precursors to prepare different solid-solution sulfides, such as (Ni0.7Fe0.3)S2/3DGA and (Co0.7Fe0.3)S2/3DGA. Our results show that engineering LDH precursors can offer an alternative for preparing diverse transition-metal sulfides for energy storage.

Hierarchically scaffolded CoP/CoP2 nanoparticles: controllable synthesis and their application as a well-matched bifunctional electrocatalyst for overall water splitting.

Transition metal phosphide (TMP) nanostructures have stimulated increasing interest for use in water splitting owing to their abundant natural sources and high activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Typically, the preparation of hierarchical TMPs involves the utilization of expensive or dangerous phosphorus sources, and, in particular, the understanding of topotactic transformations of the precursors to crystalline phases-which could be utilized to enhance electrocatalytic performance-remains very limited. We, herein, report a controllable preparation of CoP/CoP2 nanoparticles well dispersed in flower-like Al2O3 scaffolds (f-CoP/CoP2/Al2O3) as a bifunctional electrocatalyst for the HER and OER via the phosphorization of a flower-like CoAl layered double hydroxide precursor. Characterization by in situ X-ray diffraction (XRD) monitored the topotactic transformation underlying the controllable formation of CoP/CoP2via tuning the phosphorization time. Electrocatalytic tests showed that an f-CoP/CoP2/Al2O3 electrode exhibited a lower onset potential and higher electrocatalytic activity for the HER and OER in the same alkaline electrolyte than electrodes of flower-like and powdered CoP/Al2O3. The enhanced electrochemical performance was experimentally supported by measuring the electrochemically active surface area. The f-CoP/CoP2/Al2O3 composite further generated a current density of 10 mA cm-2 at 1.65 V when used as a bifunctional catalyst for overall water splitting. Our results demonstrate that the preparation route based on the LDH precursor may provide an alternative for investigating diverse TMPs as bifunctional electrocatalysts for water splitting.

Photodeposited Pd Nanoparticles with Disordered Structure for Phenylacetylene Semihydrogenation.

Developing effective heterogeneous metal catalysts with high selectivity and satisfactory activity for chemoselective hydrogenation of alkyne to alkene is of great importance in the chemical industry. Herein, we report our efforts to fabricate TiO2-supported Pd catalysts by a photodeposition method at room temperature for phenylacetylene semihydrogenation to styrene. The resulting Pd/TiO2 catalyst, possessing smaller Pd ensembles with ambiguous lattice fringes and more low coordination Pd sites, exhibits higher styrene selectivity compared to two contrastive Pd/TiO2 samples with larger ensembles and well-organized crystal structure fabricated by deposition-precipitation or photodeposition with subsequent thermal treatment at 300 °C. The sample derived from photodeposition exhibits greatly slow styrene hydrogenation in kinetic evaluation because the disordered structure of Pd particles in photodeposited Pd/TiO2 may prevent the formation of ß-hydride phases and probably produce more surface H atoms, which may favor high styrene selectivity.

Triple-Confined Well-Dispersed Biactive NiCo2S4/Ni0.96S on Graphene Aerogel for High-Efficiency Lithium Storage.

Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clay compounds, have attracted increasing interest in electrochemical energy storage, in the main form of LDH precursor-derived transition metal oxides (TMOs). One typical approach to improve cycling stability of the LDH-derived TMOs is to introduce one- and two-dimensional conductive carbonaceous supports, such as carbon nanotubes and graphene. We herein demonstrate an effective approach to improve the electrochemical performances of well-dispersed biactive NiCo2S4/Ni0.96S as anode nanomaterials for lithium-ion batteries (LIBs), by introducing a three-dimensional graphene aerogel (3DGA) support. The resultant 3DGA supported NiCo2S4/Ni0.96S (3DGA/NCS) composite, obtained by sulfuration of NiCo-layered double hydroxide (NiCo-LDH) precursor in situ grown on the 3DGA support (3DGA/NiCo-LDH). Electrochemical tests show that the 3DGA/NCS composite indeed delivers the greatly enhanced electrochemical performances compared with the NiCo2S4/Ni0.96S counterpart on two-dimensional graphene aerogel, i.e., a high reversible capacity of 965 mA h g-1 after 200 cycles at 100 mA g-1 and especially a superlong cycling stability of 620 mA h g-1 after 800 cycles at 1 A g-1. The enhancements could be ascribed to the compositional and structural advantages of boosting electrochemical performances: (i) well-dispersed NiCo2S4/Ni0.96S nanoparticles with interfacial nanodomains resulting from both the dual surface confinements of the 3DGA support and the crystallographic confinement of NiCo-well-arranged LDH crystalline layer, (ii) an appropriate specific surface area and a wide pore size distribution of mesopores and macropores, and (iii) highly conductive 3DGA support that is measured experimentally by using electrochemical impedance spectra to underlie the enhancement. Our results demonstrate that the tunable LDH precursor-derived synthesis route may be extended to prepare various transition metal sulfides and even transition metal phosphides for energy storage with the aid of tunable cationic type and molar ratio.

Nitrogen-doped carbon and high-content alumina containing bi-active cobalt oxides for efficient storage of lithium.

Low-content ultrathin coating of non-active alumina (Al2O3) has been extensively utilized as one of the most effective strategies to improve electrochemical performances of electrodes for lithium-ion batteries (LIBs), however, typically by employing expensive atomic layer deposition equipment. We herein demonstrate a simple preparation of high-content and well-dispersed Al2O3 (24.33wt.%)-containing multi-component composite (CoO/Co3O4/N-C/Al2O3) by calcination of melamine/CoAl-layered double hydroxide (CoAl-LDH) mixture. The resulting composite bundles the advantages expected to improve electrochemical performances: (i) bi-active CoO/Co3O4, (ii) highly conductive N-doped carbon, and (iii) N-doped carbon and high-content non-active Al2O3 as buffering reagents, as well as (iv) good distribution of bi- and non-active components resulted from the lattice orientation and confinement effect of the LDH layers. Electrochemical evaluation shows that the composite electrode delivers a highly enhanced reversible capacity of 1078mAhg(-1) after 50cycles at 100mAg(-1), compared with the bi-active CoO/Co3O4 mixtures with and without non-active Al2O3. Transmission electron microscopy/scanning electron microscopy observations and electrochemical impedance spectra experimentally provide the information on the good distributions of multiple components and the improved conductivity underlying the enhancements, respectively. Our LDH precursor-based preparation route may be extended to design and prepare various multi-component transition metal oxides for efficient lithium storage.

Preparation of Nickel-Aluminum-Containing Layered Double Hydroxide Films by Secondary (Seeded) Growth Method and Their Electrochemical Properties.

Thin films of nickel-aluminum-containing layered double hydroxide (NiAl-LDH) have been prepared on nickel foil and nickel foam substrates by secondary (seeded) growth of NiAl-LDH seed layer. The preparation procedure consists of deposition of LDH seeds from a colloidal suspension on the substrate by dip coating, followed by hydrothermal treatment of the nanocrystals to form the LDH film. The secondary grown film is found to provide a higher crystallinity and more uniform composition of metal cations in the film layer than the in situ grown film on seed-free substrate under identical hydrothermal conditions. A systematic investigation of the film evolution process reveals that the crystallite growth rate is relatively fast for the secondary grown film because of the presence of LDH nanocrystal seeds. Electrochemical performance of the resulting NiAl-LDH films as positive electrode material was further assessed as an example of their practical applications. The secondary grown film electrode delivers improved recharge-discharge capacity and cycling stability compared with that of the in situ grown film, which can be explained by the existence of a unique microstructure of the former. Our findings show an example for the effective fabrication of LDH film with controllable microstructure and enhanced application performance through a secondary (seeded) growth procedure.

Preparation and regulating cell adhesion of anion-exchangeable layered double hydroxide micropatterned arrays.

We describe a reliable preparation of MgAl-layered double hydroxide (MgAl-LDH) micropatterned arrays on gold substrate by combining SO3(-)-terminated self-assembly monolayer and photolithography. The synthesis route is readily extended to prepare LDH arrays on the SO3(-)-terminated polymer-bonded glass substrate amenable for cell imaging. The anion-exchangeable MgAl-LDH micropattern can act both as bioadhesive region for selective cell adhesion and as nanocarrier for drug molecules to regulate cell behaviors. Quantitative analysis of cell adhesion shows that selective HepG2 cell adhesion and spreading are promoted by the micropatterned MgAl-LDH, and also suppressed by methotrexate drug released from the LDH interlayer galleries.

Zirconium phenylphosphonate-anchored methyltrioxorhenium as novel heterogeneous catalyst for epoxidation of cyclohexene.

Epoxidation of olefins to epoxides is widely recognized as an important unit process in the manufacture of fine chemicals and intermediates. Developing an environmentally benign heterogeneous catalytic system for olefin epoxidation with high activity and selectivity is still a challenge in this research field. Herein, we report our attempts to synthesize novel zirconium phenylphosphonate-anchored methyltrioxorhenium (MTO/ZrPP) heterogeneous catalysts by a conventional impregnation method and evaluate their catalytic performance for epoxidation of cyclohexene using urea-hydrogen peroxide adduct (UHP) as oxidant without the addition of base ligands. The MTO/ZrPP catalyst samples are characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), inductively coupled plasma emission spectrometry (ICP-ES), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and solid-state (1)H magic-angle spinning nuclear magnetic resonance ((1)H MAS NMR) techniques. Meanwhile, the density functional theory (DFT) calculation is carried out to further understand the structure feature and interactions of the MTO/ZrPP catalyst. It is revealed that MTO is anchored on support surface by the favored hydrogen-bonding interaction between two oxo ligands of MTO and two H atoms from the adjacent phenyls of ZrPP. MTO/ZrPP catalyst displays excellent catalytic activity for cyclohexene epoxidation. Moreover, only cyclohexene oxide production can be obtained under the employed reaction conditions.

Co/CoO/CoFe2O4/G nanocomposites derived from layered double hydroxides towards mass production of efficient Pt-free electrocatalysts for oxygen reduction reaction.

Development of a simple, reproducible and cost-effective protocol for mass production of non-precious-metal electrocatalysts for oxygen reduction reaction (ORR) is still challenging but highly desirable for their practical applications in industry. Herein, we developed a facile and scalable method to directly produce graphene (G) supported CoFe-LDHs and successfully used them as a precursor for mass production of Co/CoO/CoFe2O4/G as a low-cost and Pt-free efficient electrocatalyst, which exhibits comparable electrocatalytic activity and much better durability for ORR in comparison with commercial Pt/C catalysts. The result may provide a way for cost-effective production of ORR electrocatalysts on a large scale for practical applications.