•Two new ruthenium complexes have been synthesized and characterized.•Complex 1 shows great photocytotoxicity towards Hela cells (IC50 = 1.9 μM).•Complex 1 inhibits Hela cell proliferation by induction of G2M phase cycle arrest and cells apoptosis.Two new Ru(II) complexes [Ru(dtzp)(dppz)Cl]+1 and [Ru(dtzp)(dppz)CH3CN]2+2 (dtzp = 2,6-di(thiazo1-2-yl)pyridine; dppz = dipyrido[3,2-a:2′,3′-c]phenazine) have been synthesized and evaluated as photodynamic anticancer agents. The results of the spectra titration, thermal denaturation and electrophoresis experiments suggest that both complexes could intercalatively bind to DNA and photocleave DNA efficiently by ROS generation and photoinduced electron transfer. When incubated under visible light (470 nm), complex 1 and 2 generate great photocytoxicity towards Hela cells in both 2D cancer cell monolayer and 3D MCTS cancer models, and a much greater photocytotoxicity was observed for complex 1, which may be associate with its' larger cellular uptake efficiency and stronger absorption at 470 nm. Flow cytometry analysis and immunofluorescence assay revealed that complex 1 inhibited Hela cell proliferation through G2M phase cycle arrest and cell apoptosis and could generate great photodamage to chromatin DNA. Complex 1 may be a prominent PDT candidate used for treating cervical carcinoma.

•Two new ruthenium complexes based pH and nucleic acids sensors have been synthesized and characterized.•Complex 1 shown to be a naked-eye colorimetric sensor for nucleic acids.•Complex 2 behaves as a near-infrared lysosome pH fluctuation tracker.Two new Ru(II) complexes [Ru(bim)2(dppz)]2+ 1 and [Ru(bim)2(pip)]2+ 2 ((bim = 2,2′-biimidazole; dppz = dipyrido[3,2-a:2′,3′-c]phenazine, pip = 2-phenyl-1H-imidazo[4,5-f][1,10]phenan-throline) have been synthesized, characterized and evaluated for pH and nucleic acids detection. Both complexes respond sensitively to pH in solution with remarkable red shifts at MLCT band and display distinct color changes. Complex 1 has also shown to be an interesting naked-eye colorimetric sensor for nucleic acids with significant color change from red to yellow upon binding to DNA or RNA. Complex 2 was non-fluorescent under neutral or basic conditions, while under acidic conditions, it emits bright fluorescence at a near-infrared wavelength exhibiting a pH-dependent fluorescent turn-on property. Cell fluorescent imaging results indicate that complex 2 could cross cell membranes, localize at lysosomes, and monitor the change of intracellular pH. The large Stokes shift, low background fluorescence, and excellent stability and solubility make complex 2 a promising lysosomes pH sensor during physiological and pathological processes.Download high-res image (104KB)Download full-size image

•Zeolite Phi with Si/Al ratios of 2–30 has been synthesized with a number of organic and inorganic bases as additives.•These additives, such as TMA+ ion and other alternatives, are not “templates”, nor “structure-directing agents”.•They merely affect the crystallization kinetics.•The structure of the products can be described as CHA topology, but with faults in ABC-D6R stacking sequences.The crystallization of alumino-silicate zeolites of CHA structure in the system Na2O-K2O-Al2O3-SiO2-H2O is kinetically controlled, and occurs only in very narrow windows of compositions and hydrothermal conditions. This paper elaborates a new method to synthesize CHA zeolites with Si/Al ratios in a wide range, by means of adding some weak bases to modify the crystallization kinetics in favor of the desired CHA framework. A number of organic and inorganic bases are feasible for this purpose. Pure crystalline CHA materials with Si/Al = 2–30 have been obtained. These weak bases, either organic or inorganic, are not “templates”, nor “structure-directing agents”. The powder XRD patterns of obtained CHA type materials feature both broad and narrow peaks. And additional peaks that belong to low symmetry structures appear. These observations are in coincidence with earlier reported zeolite Phi, indicating existences of stacking faults in the ABC-D6R sequences.Download high-res image (253KB)Download full-size image

•Two kinds of 3D α-MnO2 were fabricated from two different redox reactions.•The larger difference of redox reaction yields dandelion-like α-MnO2.•Dandelion-like α-MnO2 exhibits the superior electrochemical activities.•The larger redox potential produces larger surface area and richer defects.The morphology of manganese dioxides has great effects on their electrocatalytic activities. Herein, two different types of three-dimensional (3D) radial α-MnO2 (dandelion- and urchin-like) catalysts are readily fabricated via two different redox reactions through the hydrothermal method, and their electrocatalytic activities are studied for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). As a result, the dandelion-like α-MnO2 exhibits a higher electrocatalytic performance than urchin-like α-MnO2, with a lower overpotential (20 mV lower for ORR and 90 mV lower for OER), higher mass activity and lower Tafel slope. The excellent electrocatalytic activity of dandelion-like α-MnO2 can be attributed to its relatively larger BET and electrochemical active surface area, richer defects, higher amount of Mn3+, and less charge transfer resistance. Our results shed insights into developing new way in constructing the deficient α-MnO2 bifunctional oxygen electrocatalysts.Download high-res image (224KB)Download full-size image

In this work, peanut protein isolate (PPI) was grafted with maltodextrin (MD) through the ultrasound-assisted Maillard reaction. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed a link between PPI and MD. The substantially increased accessibility of the major subunits (conarachin, acidic subunit of arachin, and basic subunit of arachin) in PPI under high-intensity ultrasound treatment led to changes in the degree of graft (DG), zeta-potential, protein solubility, and surface hydrophobicity of conjugates. Emulsion systems (20% v/v oil, 2.0% w/v PPI equivalent, pH 3.8) formed by untreated PPI, PPI-MDC (PPI-MD conjugates obtained with wet-heating alone), and UPPI-MDC (PPI-MD conjugates obtained with ultrasound-assisted wet heating) were characterized using a light-scatter particle size analyzer and confocal laser scanning microscope. Results showed that emulsions of untreated PPI and PPI-MDC were not stable due to immediate bridging flocculation and coalescence of droplets, whereas that formed by UPPI-MDC with 32.4% DG was stable with a smaller mean droplet size. It was believed that high-intensity ultrasound promoted production of glycated PPI, which was soluble and surface active at pH 3.8 and thus improved emulsification properties for UPPI-MDC. This study shows that glycated PPI by ultrasound-assisted Maillard reaction is an effective emulsifying agent for low pH applications.

Nickel cobalt sulfide (NiCo2S4), a recently reported novel electrode material, has a higher electric conductivity than that of NiCo2O4. We describe a facile one-step route to the development of burl-like NiCo2S4 on carbon fiber paper/cloth (CFP/CFC) used as electrodes for supercapacitors. The influence of the carbon substrate on the crystal structure and electrochemical performance of the NiCo2S4 electrodes is evaluated. We obtained a pure phase of NiCo2S4 over a CFP substrate, whereas, a mixed phase over a CFC substrate. Superior pseudocapacitive performance is achieved over NiCo2S4/CFP with a large specific capacitance of 0.83 F cm−2 at a high current density of 25 mA cm−2. The capacitance loss is 24.1% after 5000 cycles at a current density of 20 mA cm−2, displaying good cyclability and high rate capability.

•Facile and scalable strategy for the growth of bunched β-FeOOH nanorod arrays.•Bunched β-FeOOH nanorod arrays with high surface area and porous morphology.•Improved reversible capacity and rate capability were achieved.•Flexible anode electrodes without conductive additives and polymer binders.Significant effort has been made to explore high-performance anode materials for flexible lithium-ion batteries. We report a facile hydrothermal route to synthesis self-organized bunched akaganeite (β-FeOOH) nanorod arrays directly grown on carbon cloth (CC/β-FeOOH NRAs). Interestingly, the single nanorod is assembled by numerous small nanowires. A possible growth mechanism for this unique structure is proposed. Owning to the essential crystal structure of β-FeOOH (body-centered cubic), porous morphology, high surface area and direct growth on current collector, the prepared CC/β-FeOOH NRAs manifest a very high reversible capacity of ≈2840 mAh g−1 (2.21 mAh cm−2), remarkable rate capability 568 mAh g−1 (0.43 mAh cm−2) at 10C, stable cycling performance and greater mechanical strength.

Branched α-MnO2 nanorods are synthesized using a facile hydrothermal method without surfactants or templates. The formation of α-MnO2 with different morphologies, including branched nanorods and nanorods with controllable length, is achieved by controlling the starting concentration of reactants. The morphology and structure of the branched α-MnO2 nanorods are fully characterized and the growth mechanism is proposed based on the experimental observation. The novel structures presented here enrich the nanoscale community of α-MnO2 materials, thus enabling greater potential applications. The electrochemical properties of as-synthesized branched α-MnO2 nanorods are also studied by cyclic voltammetry (CV) and galvanostatic charge/discharge measurement. The branched α-MnO2 nanorod electrode shows a high specific capacitance of 182 F g−1 at a current density of 2 A g−1, with a good rate capability (72.5% at 64 A g−1) and excellent cycling stability.

•Carbon coated MnOx hierarchical architectures with controllable size and morphologies were prepared.•Carbon layer displayed multifunction: chemical protection and enhancement of the visible light absorption.•Carbon coated MnOx products exhibit semiconductors feature with enhanced photocatalytic activities.Carbon coated MnOx (MnOx@C) with various novel and complex 3D hierarchical architectures self-assembled from different building blocks were successfully synthesized by a hydrothermal method in glucose-mediated processes. The morphology modulation of MnOx@C could be easily realized simply by adjusting the amount of glucose added into the reaction system. The formation mechanisms for different hierarchical architectures were proposed on the basis of time-dependent experiments. An investigation on UV–visible absorption spectroscopy revealed that the as-synthesized MnOx@C expanded the light absorption from UV region to visible light region. Specifically, when 0.45 g of glucose was used, the samples (ε-MnO2-C-0.45 and MnO-C-0.45) obtained from different calcination process exhibited the semiconductor feature with a band gap of 1.9 eV and 1.84 eV, respectively. In addition, the carbon coating on MnOx provided good chemical protection for MnOx and greatly improved its photostability. The laser heating effect for ε-MnO2@C structures were also studied. The ε-MnO2@C structures could be stable at a high laser power of 1200 μW, which suggested significantly enhanced photostability. When used for decolorization of methyl orange under visible light (λ ⩾ 420 nm), the MnOx@C structures exhibited much higher activities than pure MnOx. The decolorization rate for the optimum catalyst ε-MnO2-C-0.45 could reach above 90% within 10 min.

•Ultrathin mesoporous NiCo2O4 nanosheets on carbon fiber paper were prepared by a facile method.•The electrode possesses a high specific capacitance of 999 F g−1 at 20 A g−1.•The capacitance loss is 15.6% after 3000 cycles (discharged at 10 A g−1).Two-dimensional ultrathin mesoporous NiCo2O4 nanosheets on carbon fiber paper (CFP) are synthesized through a facile solvothermal method combined with a post thermal treatment. The well interconnected ultrathin NiCo2O4 nanosheets directly grown on the carbon nanofibers could allow for easy diffusion of the electrolyte, shorten the transport path of ion and electron and accommodate the strain during cycling. As a result, superior pseudocapacitive performance is achieved with large specific capacitance of 999 F g−1 at a high current density of 20 A g−1. The capacitance loss is 15.6% after 3000 cycles at a current density of 10 A g−1, displaying good cycle ability and high rate capability.

•[Ru(bpy)2(itatp)]2+ shows significant selectivity to human telomeric G-quadruplex.•[Ru(bpy)2(itatp)]2+ could convert telomeric sequence into antiparallel G-quadruplex structure.•[Ru(bpy)2(itatp)]2+ could destroy the parallel structure of c-myc G-quadruplex.Indoloquinoline and its derivatives have been reported to be a kind of efficient G-quadruplex binder and have been found to interact preferentially to intramolecular G-quadruplex and inhibit telomerase activity in human K562 cells and SW620 cells. In contrast to indoloquinoline derivatives, much less is known about the metal complex based on indoloquinoline or its derivative. In this report, we studied the interaction of ruthenium complex [Ru(bpy)2(itatp)]2+ containing indoloquinoline moiety with human telomeric G-quadruplex DNA (Telo22) and c-myc G-quadruplex DNA (Pu27) by UV–visible (UV–Vis), fluorescence spectroscopy, fluorescent intercalator displacement (FID), thermal denaturation studies and CD spectroscopy. The results suggest that [Ru(bpy)2(itatp)]2+ displays a strong π–π stacking interaction with human telomeric G-quadruplex with a high binding constant (∼107 M−1), but just exhibits moderate binding affinity to c-myc G-quadruplex, thus showing significant selectivity to human telomeric G-quadruplex. The CD titration results indicate that [Ru(bpy)2(itatp)]2+ could effectively convert Telo22 into antiparallel G-quadruplex conformation, while in the c-myc G-quadruplex case, instead of promoting Pu27 to fold into G-quadruplex, [Ru(bpy)2(itatp)]2+ destroys the parallel G-quadruplex structure of Pu27.Graphical abstract

•Both complexes could bind to and stabilize human telomeric G-quadruplex.•Complex 1 could convert telomeric sequence into antiparallel G-quadruplex structure.•Complex 2 could promote the formation of parallel G-quadruplex.G-quadruplex structures are attractive targets for the development of anticancer drugs, as their formation in human telomere could impair telomerase activity, thus inducing apoptosis in cancer cells. Vast majority of G-quadruplex binding molecules have been designed and synthesized. Ruthenium complexes have also been reported to induction or stabilization of G-quadruplex structure of human telomeric sequence, whereas most of them generally promote the formation of antiparallel or hybrid-type G-quadruplex structure. Ruthenium complex that selectively promotes the formation of parallel G-quadruplex structure has rarely been reported. We reported here the interaction of two ruthenium complexes [Ru(bpy)2(mitatp)]2+1 and [Ru(phen)2(mitatp)]2+2 (bpy = 2,2′ bipyridine, phen = 1,10-phenanthroline, mitatp = 5-methoxy-isatino[1,2-b]-1,4,8,9-tetraazatriphenylene) containing indoloquinoline moiety with human telomeric G-quadruplex DNA (Telo22). Complex 1 binds to Telo22 tightly via a stable π–π stacking interaction and efficiently stabilizes the G-quadruplex structure. Circular dichroism (CD) spectra titration results suggest that complex 1 could induce Telo22 to fold into antiparallel G-quadruplex conformation. Complex 2 exhibits moderate G-quadruplex binding and stabilizing ability, while CD titration data reveals that complex 2 could promote the formation of parallel G-quadruplex structure.Graphical abstract

•ZIF-68 with exceptional stability was firstly synthesized by hydrothermal method.•ZIF-68 was firstly used to catalyze the cyclic addition reaction of CO2.•High yield of cyclic carbonate was obtained under mild conditions.•The presence of acid–base site in ZIF-68 plays a critical role in the reaction.An efficient heterogeneous catalyst, namely, zeolitic imidazolate framework-68 (ZIF-68), was developed for the synthesis of cyclic carbonate from CO2 and styrene oxide in the absence of any solvents or co-catalysts under mild reaction conditions (120 °C and 1.00 MPa). The textural properties of the ZIF-68 catalyst were determined by the powder X-ray diffraction, N2 adsorption–desorption and thermal analysis. The acid–base property of ZIF-68 catalyst was investigated by NH3 and CO2 temperature-programmed desorption methods. The results indicate that the yield of cyclic carbonate reached up to 93.3% after 12 h in the mild reaction conditions. Moreover, the ZIF-68 catalyst could be successfully reused for three times without any significant loss in catalytic activity.

In this work, we report the preparation of a free-standing membrane with strong mechanical stability and flexibility through a facile vacuum filtration approach. A field-emission scanning electron microscopy image demonstrates that the membrane composed of MnO2 nanowires is 50 nm in width and up to 100 μm long and the nanowires are assembled in parallel into bundles. A possible formation mechanism for the ultralong nanowires and the free-standing membrane has been proposed. Meanwhile, the properties of the membrane could be controlled by incorporating different materials to achieve composite membranes. In order to demonstrate the broad applicability of the MnO2 membrane, we fabricate a variety of composite membranes exhibiting various novel properties including magnetism and reversibly switchable wettability between hydrophilicity and hydrophobicity through various material modification, including CoFe2O4 nanoparticles and organic triethoxy(octyl)silane. Furthermore, the free-standing membrane could also simultaneously be functionalized with two materials, which reveal multiple properties. The synthesis method of a free-standing MnO2 membrane is simple and environmentally friendly, and it is easily scalable for industry. These composite membranes constitute a significant contribution to advanced technology.Keywords: MnO2; multifunctional free-standing membrane; ultralong nanowires;

A hydrothermal process has been used to synthesize manganese oxides of various crystalline structures and morphologies, such as α-, β-, γ-MnO2, MnOOH and Mn3O4. The nanostructured materials were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H2-TPR) techniques. The crystalline evolution mechanism of converting β-MnO2 or MnOOH to α-MnO2 was studied. The crystalline-dependent effect of the nanostructured manganese oxides was explored by using toluene combustion as a probe reaction. Results indicated that the catalytic activity of α-MnO2 with ultra-long nanowires is higher than that of manganese oxides with other crystalline structures. The catalytic activity was correlated with the H2-TPR and XPS results.

We report for the first time a novel and rapid (1 h) synthesis method for birnessite-type MnO2 nanostructures via a polyol-reflux process through oxidizing MnCl2 with H2O2 under basic conditions in the presence of polyvinylpyrrolidone (PVP). Influencing factors such as the dosage of reactants and the reaction times are systematically investigated. The molar ratios of OH/Mn played an important role in the formation of birnessite-type MnO2 nanostructure with good crystallinity and ordered 3D nanostructures. A possible formation mechanism for the nanostructure was proposed. The flower-like birnessite-type MnO2 nanostructure is composed of nanosheets with an average diameter ca. 300–500 nm and shows mesoporous characteristics with a pore diameter of 20 nm. Due to its unique mesoporous structure, the birnessite-type MnO2 exhibits excellent ability to remove organic pollutants (Ponceau 2R) and shows a potential application as an electrochemical capacitor.

•The Al2O3–MO showed high thermal stability.•The Al2O3–MO catalysts have large amount of surface oxygen species.•The Al2O3 pillars could promote the mobility of the active oxygen.•The Al2O3–MO catalysts showed excellent DME catalytic combustion activity.•The transient response method was used to evaluate the role of the lattice oxygen.Al2O3-pillared layered manganese oxides (Al2O3–MO), used as catalyst for the catalytic combustion of dimethyl ether (DME), were characterized by XRD, SEM-TEM, N2 adsorption and desorption, O2-TPD and XPS techniques. The Al2O3–MO shows a relative high thermal stability. The layered structure with a basal spacing of 0.67 nm could be maintained up to 500 °C. The O2-TPD technique showed that all the Al2O3-pillared layered manganese oxides catalysts have large amount of surface oxygen species and the Al2O3 pillars could promote the mobility of the active oxygen. Sample Al2O3–MO (300 °C) with large amount of lattice oxygen species and higher oxygen mobility demonstrates excellent activity in the catalytic combustion of DME with a light-off temperature of 140 °C and a complete combustion temperature of 149 °C. The catalytic activity of the sample Al2O3–MO (300 °C) was stable up to 200 h. The transient response method was carried out to account for the participation of the lattice oxygen in the catalytic reaction. The results showed that the lattice oxygen of manganese oxide (MnO) was consumed in the combustion reaction and that reduced manganese oxide was reoxidized with O2.

Well-ordered organic–inorganic hybrid layered manganese oxide nanocomposites (CTAB-Al-MO) with excellent decolorization performance were prepared through a two-step process. Specifically, the MnO2 nanosheets were self-assembled in the presence of CTAB, and subsequently pillared with Keggin ions. The obtained CTAB-Al-MO with the basal spacing of 1.59 nm could be stable at 300 °C for 2 h and also possesses high total pore volumes (0.41 cm³ g−1) and high specific BET surface area (161 m2 g−1), which is nine times larger than that of the pristine (19 m2 g−1). Possible formation process for the highly thermal stable CTAB-Al-MO is proposed here. The decolorization experiments of methyl orange showed that the obtained CTAB-Al-MO exhibit excellent performance in wastewater treatment and the decolorization rate could reach 95% within 5 min.Graphical AbstractWell-ordered organic–inorganic hybrid LMO nanocomposites (CTAB-Al-MO) with excellent decolorization performance were prepared through a two-step process. Specifically, the MnO2 nanosheets were self-assembled by CTAB, and subsequently pillared with Keggin ions.Highlights► A two-step synthesis method was used to prepare the CTAB-Al-MO. ► The CTAB-Al-MO has the large basal spacing and high specific BET surface area. ► The thermal stability of the well-ordered CTAB-Al-MO could obviously improve. ► The CTAB-Al-MO exhibits excellent oxidation and absorption ability to remove organic pollutants.

Branchy structures of β-MnO2 were prepared through a two-step process including MnO2 nanosheet-assisted hydrothermal synthesis of branchy γ-MnOOH precursor and followed by calcination of the obtained precursor. After the calcination, the branchy feature was retained for β-MnO2 with two types of the end structures, i.e., pyramidate ends and opened ends. The assembly and shedding mechanism was proposed to explain the formation of the branchy structure. This nanosheet-assisted hydrothermal method studied here offers a new approach for synthesis of other layered materials. Furthermore, the decolorization experiments of methyl blue (MB) showed that the obtained β-MnO2 exhibited excellent ability to remove the MB dye with the assistance of hydrogen peroxide.Highlights► Branchy β-MnO2 was prepared through a MnO2 nanosheet-assisted hydrothermal process. ► Branches have sunk structures, with some pyramidate ends closed and others opened. ► The branchy structure was formed through the assembly and shedding mechanism. ► The branchy β-MnO2 shows excellent ability to remove the organic pollutants.

Manganese oxides with different crystalline structures, namely α-, β-, and γ-, were synthesized by a facile hydrothermal method and characterized by X-ray powder diffraction (XRD), surface area analyzer, scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H2-TPR) techniques. The dimethyl ether combustion was used as a probe reaction to explore the crystalline phase effect of the manganese oxides. The results revealed that α-MnO2 with nanorod shape possesses higher catalytic activity compared to the other two manganese oxides. Their different catalytic activities for dimethyl ether combustion have also been discussed in terms of surface areas, crystalline structures and oxygen mobilities.Graphical abstractManganese oxides with different crystalline phases synthesized by the hydrothermal method showed varied morphology and specific surface area.Highlights► Manganese oxides with different crystal structures were prepared by the facile hydrothermal method. ► The crystalline phase effect of the manganese oxides was explored in detail. ► α-MnO2 with nanorod shape possesses higher catalytic activity. ► The difference in activity is discussed in terms of surface area, structure and oxygen mobility.

Cryptomelane-type manganese oxide (OMS-2) was rapidly prepared under ultrasonic irradiation in short time. Characterization results using X-ray powder diffraction (XRD), surface area analyzer, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), oxygen temperature-programmed desorption (O2-TPD) revealed that ultrasonic irradiation has tremendous effect on the surface area, morphology, surface defects, and redox properties of the OMS-2 materials. The OMS-2 prepared via ultrasonic irradiation shows nanoneedle morphology with smaller crystallite size, larger surface area (120.4 m2/g), more surface defects, and higher oxygen mobility, thus it demonstrates excellent activity in the catalytic combustion of dimethyl ether with a start-off temperature of 160 °C and a complete combustion temperature of 172 °C.OMS-2 material prepared through the conventional method shows perfect nanorod morphology; however, the OMS-2 prepared through the ultrasonic process shows nanoneedle morphology with more surface defects.Highlights► Nanoneedle OMS-2 was prepared through ultrasonic irradiation in a short time. ► Ultrasonic irradiation has a great effect on the surface area, morphology and surface defects. ► The prepared OMS-2 shows excellent redox property and catalytic activity.

A new route to synthesize efficient Ce-doped manganese oxide octahedral molecular sieves (OMS-2) catalysts using birnessite precursor was developed. Their catalytic activities in the combustion of dimethyl ether (DME) were evaluated. N2 adsorption, XRD, H2-TPR, O2-TPD and XPS techniques were employed in the catalyst characterization. A promoting effect of Ce in the Ce/OMS-2 catalysts on the catalytic activity was observed. For the most active sample with a Ce/Mn ratio of 0.07 (starting Ce/Mn molar ratio, Ce-7/OMS-2), the light-off temperature (the temperature acquired for 10% DME conversion, T10) and full-conversion temperature (the temperature acquired for 90% DME conversion, T90) were 149 and 159 °C, respectively. The catalytic activity of Ce-7/OMS-2 was stable up to 50 h. Ce-7/OMS-2 is a promising catalyst for DME catalytic combustion. The mobility of the active lattice oxygen, the larger amount and the more facile supply of the lattice oxygen species on the surface of Ce/OMS-2 are of crucial importance for the reaction.

Monolithic catalysts for catalytic combustion of dimethyl ether (DME) were prepared by a dip-coating method using Al2O3/cordierite as support and manganese oxide octahedral molecular sieve (OMS-2) as active component. The effect of different types of organic polymer binder and the coating times of active component on the performance of DME combustion were investigated. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), hydrogen temperature-programmed reduction (H2-TPR) and oxygen temperature-programmed desorption (O2-TPD) techniques. The results showed that the best catalyst was the one using methoxy polyethylene glycol (MPEG) as the coating binder by one-time coating. The active component OMS-2 was in a cluster form and homogeneously dispersed on the surface of the support because of the strong interaction between OMS-2 and Al2O3 coating. The Al2O3 coating could significantly improve the surface area of catalysts, and thus enhance the activity performance. The highest catalytic activity for DME combustion with a complete combustion temperature (t90) of 257°C was obtained.

To achieve high-performance fuel cells and metal–air batteries, inexpensive and earth-abundant catalysts with enhanced activity and durability for the oxygen reduction reaction (ORR) are currently sought after. Herein, three-dimensional (3D) α-MnO2 and ε-MnO2 hierarchical star-like architectures with tunable crystal phases and desirable ORR activity were readily prepared by a facile hydrothermal method with no surfactants or templates. The effects of reaction temperature, anion type, and dwell time on the morphologies of the MnO2 products were studied in detail, and the possible formation mechanism of the 3D MnO2 hierarchical stars was proposed. Due to the improved electrical conductivity and O2 adsorption ability, the resulting α-MnO2 catalyst showed substantially enhanced ORR activity, compared to the ε-MnO2 and bulk MnO2 catalysts, with a more positive onset potential, a larger limiting current density, and better durability. Our results provide a facile chemical route towards the phase-controlled synthesis of 3D MnO2 architectures, which can serve as efficient catalysts for ORR-based applications.

Nickel cobalt sulfide (NiCo2S4), a recently reported novel electrode material, has a higher electric conductivity than that of NiCo2O4. We describe a facile one-step route to the development of burl-like NiCo2S4 on carbon fiber paper/cloth (CFP/CFC) used as electrodes for supercapacitors. The influence of the carbon substrate on the crystal structure and electrochemical performance of the NiCo2S4 electrodes is evaluated. We obtained a pure phase of NiCo2S4 over a CFP substrate, whereas, a mixed phase over a CFC substrate. Superior pseudocapacitive performance is achieved over NiCo2S4/CFP with a large specific capacitance of 0.83 F cm−2 at a high current density of 25 mA cm−2. The capacitance loss is 24.1% after 5000 cycles at a current density of 20 mA cm−2, displaying good cyclability and high rate capability.