In this work, RuO2 honeycomb networks (RHCs) and hollow spherical structures (RHSs) were rationally designed and synthesized with modified-SiO2 as a sacrificial template via two hydrothermal approaches. At a high current density of 20 A g–1, the two hierarchical porous RuO2·xH2O frameworks showed the specific capacitance as high as 628 and 597 F g–1; this is about 80% and 75% of the capacitance retention of 0.5 A g–1 for RHCs and RHSs, respectively. Even after 4000 cycles at 5 A g–1, the RHCs and RHSs can still remain at 86% and 91% of their initial specific capacitances, respectively. These two hierarchical frameworks have a well-defined pathway that benefits for the transmission/diffusion of electrolyte and surface redox reactions. As a result, they exhibit good supercapacitor performance in both acid (H2SO4) and alkaline (KOH) electrolytes. As compared to RuO2 bulk structure and similar RuO2 counterpart reported in pseudocapacitors, the two hierarchical porous RuO2·xH2O frameworks have better energy storage capabilities, high-rate performance, and excellent cycling stability.Keywords: hard-template method; hollow spheres; honeycomb network; hydrous RuO2; supercapacitors;

It will be very interesting for many important reactions to endow highly active catalysts with momentum-transfer efficiency. However, the intrinsic magnetism of ferromagnetic catalysts is difficult to exploit due to the interaction between the catalyst and stirring devices. Herein, a catalytically active and super paramagnetic Co–carbon–rGO composite (CCGC) was synthesized and used as a nanoactuator to simultaneously achieve momentum-transfer and hydrolysis of NaBH4 or H3NBH3 for hydrogen production. The CCGC magnetically transferred momentum in a batch or continuous flow reactor. The external magnetic field can drive the catalyst to transfer momentum for excellent agitation. The catalyst can be fixed at an appointed position in the continuous flow for efficient separation. The separation of the catalyst from the reaction mixture also becomes facile. The CCGC showed superior retention as a pollutant adsorbent for the removal of Rhodamine B (Rh-B) from water in the absence of magnetic or mechanical stirring apparatus. The unique momentum-transfer properties, as well as excellent catalysis and adsorption, warrant its promising application in the corresponding fields.

In this article, Co-based metal organic frameworks (MOFs) with two shapes were used as pyrolysis precursor to synthesize multilayer core–shells composites loaded on reduced graphene oxide (rGO) sheets. The core–shell structures were obtained by the formation of cores from metal ions and carbon shells from carbonization of ligands. Controllable oxidation of Co cores to CoOx shells generated multilayer core–shell structures anchored onto the surface of rGO sheets. The N-doped composites were obtained by adding poly vinylpyrrolidone. The multilayer core–shells composites exhibited superior catalytic activity toward hydrogen generation compared to their single layer counterparts. By using the N-doped multilayer composites, high hydrogen generation specific rate of 5560 mL min–1 gCo–1 was achieved at room temperature. The rGO sheets in composites improved their structure stability. These catalysts exhibited high stability after used five cycling. This synergistic strategy proposes simple, efficient, and versatile blue-prints for the fabrication of rGO composites from MOFs-based precursors.

Magnetic core–shell structures provide abundant opportunities for the construction of multifunctional composites. In this article, magnetic core–shells were fabricated with Co nanoparticles (NPs) as cores and g-C3N4 as shells. In the fabrication process, the Co@g-C3N4 core–shells were anchored onto the rGO nanosheets to form a Co@g-C3N4-rGO composite (CNG-I). For hydrogen generation from the hydrolysis of NaBH4 or NH3BH3, the Co NP cores act as catalytic active sites. The g-C3N4 shells protect Co NPs cores from aggregating or growing. The connection between Co NPs and rGO was strengthened by the g-C3N4 shells to prevent them from leaching or flowing away. The g-C3N4 shells also work as a cocatalyst for hydrogen generation. The magnetism of Co NPs and the shape of rGO nanosheets achieve effective momentum transfer in the external magnetic field. In the batch reactor, a higher catalytic activity was obtained for CNG-I in self-stirring mode than in magneton stirring mode. In the continuous-flow process, stable hydrogen generation was carried out with CNG-I being fixed and propelled by the external magnetic field. The separation film is unnecessary because of magnetic momentum transfer. This idea of the composite design and magnetic momentum transfer will be useful for the development of both hydrogen generation and multifunctional composite materials.

•LiFePO4 composites were prepared by rheological phase assisted method using acetic acid as dispersant.•Rheological phase assisted method avoided the sedimentation of the precursor during drying.•The optimal composites showed enhanced electrochemical performance as cathode materials.•This economic and facile method provides a promising alternative for large-scale production of LiFePO4.LiFePO4 composites were synthesized by aqueous ball milling and carbon thermal reduction from FePO4·2H2O through a rheological phase using acetic acid as dispersant. The rheological phase assisted method using acetic acid as dispersant improved the homogeneity of mixing raw materials. Li deficiency and solid-solution Mg dopant in the lattice of LiFePO4 was created through controlled off-stoichiometry Li/Fe ratio. Li deficiency, solid-solution Mg doping and uniform carbon layer decreased electron transfer and Li-ion diffusion resistance. The optimal LiFePO4 composite exhibited a high rate capability with 153 mA·h·g−1 at 1 C and 111 mA·h·g−1 at 20 C as well as a stable capacity retention with 99% for 100 cycles at 2 C and 98% for 200 cycles at 5 C. The rheological phase assisted method from FePO4 with acetic acid as dispersant is a promising route for production of high quality LiFePO4 materials at a reasonable cost.

A LiFePO4 precursor was prepared using an aqueous mixing process combined with rheological phase technology. Due to homogeneous mixing of the starting materials, a uniform distribution of doped atoms and coated carbon in the as-prepared LiFePO4 material was obtained. There existed a Fe3+ valence state of iron in the as-prepared sample. The uniform distribution of elements and small particles, and the surface phase of Fe3+ generated through controlled off-stoichiometry, improved the electronic conductivity. The as-prepared LiFePO4 sample delivered a discharge capacity of 166 mA h g−1 at 0.1C and presented an excellent rate capacity of 148 mA h g−1 and a high potential plateau of 3.32 V at 1C. Approximately 100% capacity retention was maintained after 150 cycles at 1C or 200 cycles at 10C. This aqueous ball-milling process is a promising route for scaled-up production of LiFePO4 materials with high quality at a reasonable cost.

In this article, solid and hollow TS-1 mesocrystals (HTMs) with hierarchical porous structures were constructed through assembling TS-1 nanocrystalline blocks in a hydrothermal post-treatment method. TS-1 nanocrystalline blocks including the organic templating reagent provided solid TS-1 mesocrystals. Pre-removal of the template offered HTMs. In cyclohexanone ammoximation, the catalytic activity of HTMs depended significantly on their hollow mesocrystalline structure. Compared to solid TS-1 mesocrystals, HTMs showed excellent catalytic performances for cyclohexanone conversion with oxime selectivity up to 100%. The hollow mesocrystalline structures of TS-1 contributed to high surface areas, hierarchical porosities, robust structures, and corresponding catalytic performances.

Control of the microstructure and morphology of molecular sieve crystals will significantly affect their catalytic performances. In this paper, titanium silicalite-1 (TS-1) and silicalite-1 (S-1) crystals were synthesized under hydrothermal conditions in the presence of Mg(OH)2 nanocrystals (NCs). XRD, TEM, FT-IR, and N2 adsorption were used to characterize the structure of TS-1 and S-1 crystals. The introduction of Mg(OH)2 NCs endow the as-synthesized TS-1 and S-1 with a much more rugged surface and some voids and slits via attachment onto the surface or entrapment inside TS-1 and S-1 crystals. The crystallinity behavior, microstructure and morphology of TS-1 and S-1 also are effectively affected and modified by the presence of Mg(OH)2 NCs. The obtained TS-1 and S-1 crystals were examined as catalysts for the cyclohexanone ammoximation and vapor phase Beckmann rearrangement of cyclohexanone oxime, respectively. The highest catalytic performances of the two reactions had been obtained when the Mg(OH)2 additive amount was 10 wt%. The catalytic performance was improved when the appropriate amount of Mg(OH)2 NCs was introduced into the MFI zeolite synthesis solution.

A three-dimensional TiO2–carbon–rGO (TCG) composite was fabricated and post-treated with UV irradiation (254 nm) for 0.5 h to obtain TCG-UV. The UV irradiation improved the crystalline properties of TiO2 nanoparticles. Homogeneous UV irradiation improved the degree of disorder of carbon in TCG-UV. The rGO sheets and carbon shells improved the electrical conductivity and structural stability of TCG, and as anode materials of lithium ion batteries, a higher specific discharge capacity up to 191 mA h g−1 was obtained after 100 cycles at a current rate of 0.2C.

The active species distribution of zeolites significantly influences the catalytic performance. In this paper, titanium silicalite-1 (TS-1) was synthesized from silica sol, TiCl3 and NH3 with tetrapropyl ammonium bromide (TPAB) as the template agent. Modification with ethanolamine altered the distribution of Ti species in TS-1 particles. Some large voids as 50 × 70 nm and 70 × 110 nm existed in the inner part of modified TS-1 crystals and were responsible for improved diffusion properties and accessibility to active sites. The modified TS-1 was examined in continuous cyclohexanone ammoximation. A high conversion of cyclohexanone (98%) and oxime selectivity (100%) was still maintained after the test reaction had been carried out up to 410 h. The modified TS-1 is able to serve as a stable catalyst for continuous cyclohexanone ammoximation.

The research on the heterogeneous catalytic synthesis of tetrazoles has attracted great attention. In this paper, a tungsten atom-containing AlPO-5 microporous molecular sieve (termed as WAlPO-5) was designed and synthesized by the incorporation of tungsten atoms into the AlPO-5 skeleton with triethylamine as a structure template from pseudoboehmite, H3PO4 and tungstophosphoric acid. The incorporation of tungsten atoms into the AlPO-5 skeleton has been demonstrated by systematic characterizations. WAlPO-5 can be used as an efficient heterogeneous catalyst for the synthesis of 5-substituted 1H-tetrazoles by [3+2] cycloaddition from nitriles and sodium azide. As a novel heterogeneous catalyst, WAlPO-5 exhibits a high catalytic activity, a superior cycling stability and an excellent substrate applicability. The significant advantages of WAlPO-5, such as the simple procedure and the mild reaction conditions and as an alternative to those corrosive, hazardous and polluting homogeneous catalysts, warrant its potential application in industrial processes.

Inorganic nanoparticles (NPs) confined in carbon nanotubes (MWCNTs) will provide significantly improved performances compared to their counterparts supported on the outer walls of MWCNTs. In this paper, supercritical CO2 (sc-CO2) was used as an impregnation medium to assist the inorganic Ru precursor into the inner pores of MWCNTs. MWCNTs inner space confined Ru–MWCNTs nanocomposites were obtained after further reduction by H2. The Ru–MWCNTs show excellent catalytic performance in the hydrogenation of D-glucose. The activity and stability of the prepared Ru catalyst were much improved. This sc-CO2 assisted impregnation is an effective and environmental benign process to prepare other metal NPs confined in MWCNTs as advanced functional materials.

Recovering tungsten from the leach solution of adipic acid (ADA) synthesis by oxidizing cyclohexene over tungsten peroxide catalyst is a problem. Herein, a novel process is explored to recover tungsten and recycle catalyst in this production process. The reaction mother liquor of ADA synthesis was treated with triethylamine, and the tungsten peroxide decomposed to tungsten. The acidification of mother liquor with HNO3 leads to precipitation of tungsten in the form of H2WO4. The component of recovered reagent was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. A tungsten recovery of 97% was achieved. The regenerated catalyst was prepared from recovered tungsten. The regenerated catalyst provided a yield of ADA of 94.1%, which is comparable to the 94.5% yield of ADA with fresh catalyst. The effective recovery of tungsten and the excellent performance of regenerated catalyst show that an effective recovery approach has been developed.

The demand for a clean production process of adipic acid (AA) can be achieved by developing a synthetic route using H2O2 as the oxidant. In this paper, a green process with a recyclable catalyst system consisting of H2WO4, H2SO4 and H3PO4 was developed for the production of AA via catalytic oxidation of cyclohexene. A continuous-flow reactor was set up for the optimization of the reaction parameters and developing the industrial operation of this green process. The mixture of H2SO4 and H3PO4 as acidic promoter displays a significant improvement in the activity of catalyst and the stability of H2O2. The catalyst could be recovered and reused 20 times, and no significant loss of catalytic performance can be observed. The effect of Fe3+ ion as a possible contaminant has no serious negative effect on this reaction, and the 316L stainless steel and glass-lined steel were selected as appropriate equipment material. Calorimetry and the scale-up in batch reactor demonstrate that the reaction could be operated safely on scale. The process was scaled up in a continuous-flow pilot plant, with excellent yield (94.7%) and purity (99.0%). Some advantages such as the solvent-, phase-transfer-catalyst-, and organic additive-free and low-cost light up the application of this process in the industrial production of AA.

The oxidation-resistant acidic resins are of great importance for the catalytic oxidation systems. In this paper, the oxidatively stable acidic resins are obtained from the cation ion exchange resins (CIERs) through the thermal treatment in N2 atmosphere. The structure and properties of the thermally treated CIERs were characterized by chemical analysis, Fourier transform infrared (FT–IR) spectra, acid capacity measurement and scanning electron microscope (SEM). The thermally treated CIERs possess high acid capacity up to 4.09 mmol g–1. A partial carbonization is observed in the thermal treatment process of CIERs, but the morphology of resin spheres maintains well. The as-prepared CIERs are used as solid acids to assist the hydrogen peroxide oxidation of cyclohexene to adipic acid (ADA) with tungstic acid as the catalyst precursor. The improved yields of ADA in the recycling reaction are obtained in the presence of acidic CIERs. Meanwhile, the unproductive decomposition of H2O2 is effectively suppressed. The high yields of ADA (about 81%) are kept by the thermally treated CIERs even after the fifth cycle. The thermally treated CIERs exhibit excellent acid-catalytic performance and possess remarkable oxidation-resistant capability.Keywords: adipic acid; catalytic oxidation; oxidation-resistant resins; partial carbonization; thermal treatment;

In this article, TiO2–Carbon–rGO (GCT) three-component composite material has been constructed by anchoring TiO2 nanoparticles (NPs) encapsulated in carbon shells onto reduced graphene oxide (rGO) sheets. The structure of GCT was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption isotherms, and transmission electron microscopy (TEM). This material shows a superior retention as the anode materials in lithium ion battery with a specific discharge capacity of 188 mA h g–1 in the initial cycle and 158 mA h g–1 after 100 cycles.Keywords: composite materials; core−shell structure; lithium ion battery; reduced graphene oxide; TiO2 nanoparticles;

A novel template-activation method was used to create nanoporous carbon materials derived from core–shells@rGO sheets. The carbon materials were prepared through an acid etching and thermal activation procedure with three-dimensional Fe3O4@C@rGO composites as precursors and Fe3O4 nanoparticles as the structural template. The activation at different temperatures could provide materials with different specific surface areas. The unique nanoporous structures with large surface areas are ideal adsorbents. The nanoporous carbon materials were used as adsorbents for the removal of rhodamine B (Rh-B). C@rGO-650 illustrated better adsorption performance than the other synthesized adsorbents. It displayed good recyclability, and its highest adsorption capacity reached up to 14.8 L·g–1. The remarkable adsorption properties make nanoporous carbon a useful candidate for wastewater treatment. This template-activation method can also broaden the potential applications of core–shells@sheet structures for the construction of nanoporous carbon, which helps to resolve the related energy and environmental issues.Topics: Adsorption; Core-shell materials; Crystal structure; Distribution function; Heat treatment; Nanocomposites; Nanoparticles; Nanoporous materials; Surface reaction; Surface structure;

It will be very interesting for many important reactions to endow highly active catalysts with momentum-transfer efficiency. However, the intrinsic magnetism of ferromagnetic catalysts is difficult to exploit due to the interaction between the catalyst and stirring devices. Herein, a catalytically active and super paramagnetic Co–carbon–rGO composite (CCGC) was synthesized and used as a nanoactuator to simultaneously achieve momentum-transfer and hydrolysis of NaBH4 or H3NBH3 for hydrogen production. The CCGC magnetically transferred momentum in a batch or continuous flow reactor. The external magnetic field can drive the catalyst to transfer momentum for excellent agitation. The catalyst can be fixed at an appointed position in the continuous flow for efficient separation. The separation of the catalyst from the reaction mixture also becomes facile. The CCGC showed superior retention as a pollutant adsorbent for the removal of Rhodamine B (Rh-B) from water in the absence of magnetic or mechanical stirring apparatus. The unique momentum-transfer properties, as well as excellent catalysis and adsorption, warrant its promising application in the corresponding fields.