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The changes in fractal structure during high-temperature (1200°C) carbonisation of a Chinese non-caking coal were studied in situ by synchrotron radiation small-angle X-ray scattering (SAXS). The r...

The ethanol oxidation reaction is of critical importance to the commercial viability of direct ethanol fuel cell technology. However, owing to the poor C-C bond cleavage capability, almost all ethanol oxidation is incomplete and suffers from low selectivity toward the C1 pathway. Herein, under the support of theoretical calculations that the heterointerfaces between CoP and Pd can reduce the energy barrier of C-C bond cleavage, rich heterointerfaces in CoP/RGO-Pd hybrids were designed to improve ethanol electrooxidation performance through enhancing the selectivity toward the C1 pathway. The experimental results show that the faradaic efficiency of the C1 pathway of CoP/RGO-Pd hybrids is as high as 27.6%, surpassing most reported catalysts in the literature. As a result of this enhancement, CoP/RGO-Pd10 exhibits mass activity as high as 4597 mA·mg

The metal-free BN catalyst is a competitive candidate in oxidative dehydrogenation (ODH). The popular oxidant used is molecular O2, and the alternative soft oxidant, CO2 with better selectivity, is...

A series of Fe/h-BN catalysts promoted with Cu or Mn were prepared for Fischer-Tropsch synthesis (FTS). The physicochemical properties, crystal structures and morphologies of the catalysts were characterized by N2 physisorption, FT-IR, TPR, XPS, XRD, MES and TEM. It is found that iron oxide nanoparticles are highly dispersed on h-BN matrix due to the anchoring effect of surface defects and the accommodation of porous structures of h-BN. The characterization results indicate that strong interaction between iron oxide and h-BN is present on un-promoted catalyst, which endows the h-BN supported iron catalyst with stable properties under FTS conditions but severely retards reduction of the catalyst. The addition of Cu to Fe/h-BN can to some extent overcome the strong interaction by introducing more sites for dissociating H2. It is observed that Cu promoter can increase the reduction or carburization degree and thus enhance the FTS activity. The addition of Mn to Fe/h-BN can weaken the strong interaction by altering the electron structure of iron species. And the electron-rich Fe species are responsible for easy reduction and the enhanced FTS performance. Besides, a higher activity can be realized by co-adding Cu and Mn to the Fe/h-BN catalyst. These results suggest that the synergistic effect of Mn and Cu can largely improve the performance of Fe/h-BN catalyst without impairing the stability of the catalyst. The present study paves a way to tailor the performances of FTS catalysts with h-BN as support.

Porous Co3O4 nanoplates constructed by loosely interconnected nanoparticles were synthesized via an L-lysine assisted hydrothermal treatment and subsequent thermal annealing. The hydrothermal conditions of reaction time, reaction temperature and reactant concentrations were investigated in detail. The results suggested that the high affinity of L-lysine could effectively control the redissolution–recrystallization and even restrict the dehydration–condensation reaction of the Co(OH)2 precursor, and thus played the key role for the preparation of the resulting porous Co3O4 nanoplates. Cyclic voltammetry and amperometric methods were used to evaluate the electrochemical performance of the resulting porous Co3O4 nanoplates toward glucose sensing in an alkaline medium. The sensors constructed by the porous Co3O4 nanoplates exhibited a fast response time (within 5 s), a detection limit of 2.7 μM, a sensitivity of 212.92 μA cm−2 mM−1, a linear range from 0.05 mM to 3.2 mM and good stability at a low applied potential (0.38 V vs. Ag/AgCl), suggesting its high performance towards non-enzymatic glucose sensing.

In this study, porous activated carbon balls supported by nanoscale zero-valent iron composites (Fe@PACB-700) were used for the first time for the removal of trace Cr(VI) from aqueous solutions. The Fe@PACB-700 composites were prepared by a facile carbothermal reduction method and then characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that nZVI particles have been successfully loaded onto PACBs. Fe@PACB-700 shows an excellent Cr(VI) removal efficiency of 91.2%. The maximum adsorption capacity of Fe@PACB-700 for Cr(VI) is 22.24 mg/g, which is 4.36 times that of PACB. The residual Cr(VI) concentration is below 20 ppb with the use of 0.15 g of Fe@PACB-700, which is much lower than the allowable concentration for Cr(VI) in drinking water (0.05 mg/L). The adsorption of Cr(VI) can be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. Fe@PACB-700 still has a high removal efficiency of 80% after five cycles. Thus, Fe@PACB-700 has a great potential for Cr(VI) removal from aqueous solution. Graphical abstract.

Boron nitride (BN) has attracted great attention with an unexpected ability in aerobic catalysis. Still, its related probe reactions are relatively rare, and the effect of the BN-supported metal catalyst on O2 activation is still ambiguous, and opinions are varied. In this work, the porous BN (pBN)-supported Au catalyst with a porous structure and exposed edges exhibits high activity in the oxidative cross-esterification reactions between the aromatic and C1-C3 aliphatic alcohols at ambient temperature. The turnover frequency value for methyl benzoate is 118 h-1 at 30 °C, and the calculated apparent activation energy (Ea, 58 kJ/mol) is comparable to that of AuPd/TiO2, Ru/Al2O3, and PdBiTe catalysts. Combined with temperature-programmed desorption (TPD) results, the loading of Au enhances the desorption of O2 and the interaction with alcohols; thus, a synergistic effect between the O-rich pBN and Au is considered. The free-radical scavenger can dramatically suppress the conversion (∼6%), suggesting that the reaction proceeds via the O2* radicals. According to the vibration of νO-O, δOO-H, and νB-O-O-B detected by attenuated total reflectance-infrared spectroscopy (ATR-IR), we are prone to consider the oxygen activation route by the edge B atoms. Then, a possible L-H reaction mechanism was proposed: benzyl alcohol and O2 adsorb on the Au/pBN initially, then O2 is converted to O2*, and the α-H elimination proceeds; as the semi-acetal formed, another α-H elimination proceeds and methyl benzoate is finally formed.

The surface chemistry of catalyst plays a vital role in the catalytic process. And the effects of surface groups of porous boron nitride (p-BN) on the hydrogenation reaction have not been studied in detailed. In this work, two main surface species of Co/p-BN catalyst were tuned thermally and their roles on the hydrogenation reaction were discriminated by α, β-unsaturated aldehyde hydrogenation reaction. The surface B O content decreased at higher reduction temperature and the cobalt phase changed from CoO to the mixture of CoO and Co0. The Co/p-BN-500 exhibited the highest selectivity to C O hydrogenation. And its turnover frequency (TOF) of 13.2 h−1 is close to the optimal value of reported cobalt catalysts. When the reaction proceeds, hydrogenation rate of C O increases but that of C C decreases gradually, thus a surface groups variation was expected at the initial period. Further in-situ FTIR spectra showed the band intensity of edge N H increases as the adsorption proceeds at 50°С but it decreases as the temperature rise to 200°С, in combined with the shift of C O adsorption peak, a intermolecular hydrogen bond between edge N H and the terminal C O group was suggested, which account for the better selectivity to C O than C C.

Coating actives with carbon is an effective way to improve the performance of Ni Fe battery, and relevant study has focused on the nanoFe/FeOx, while the micron particles used in the industry have been usually ignored. Herein, we achieve the uniform and thickness-controllable carbon coating for the micron-sized dodecahedral Fe3O4, and study the influence of the carbon thickness on the performance of the Fe anode in details. As a result, capacity, rate performance and stability are improved with the increase of carbon coating because of lower charge-transfer resistance and more complete structure. However, for the first plateau (Fe0→Fe2+) which is typically applied in the industry, the improvement of the carbon coating is limited with the thickness of the carbon, owing to insufficient impact of mitigating passivation. For the second and third plateaus (Fe2+→Fe3+), with the increase of the carbon coating, the capacity and rate performance are both markedly improved because a more completed structure can better promise the conductivity. As the thickness of the carbon coating is 20 nm, the electrode exhibits 141 mAh g−1 at a high current density of 36 A g−1. These results are of great significance to the development of industrial Ni-Fe battery.

Herein, MoO3 nanowires (Fe–MoO3 NWs) along the [110] direction were successfully synthesized in the presence of Fe3+ cations. The Fe–MoO3 NWs present a large specific surface area of 174.7 m2 g−1 and rich surface –OH groups, and the possible formation mechanism of such a structure is due to the adsorption of Fe3+ cations toward non-(110) planes of MoO3 in solution with pH greater than its isoelectric point. The obtained Fe–MoO3 NWs show excellent and highly selective adsorption capacity toward quasi-phenothiazine dyes (methylene blue, toluidine blue, azure I, and acridine orange). The dye removal rate could reach 99% in 3 min, and the maximum adsorption capacity is up to 144.3 mg g−1 and the adsorption is up to 28.86 mg g−1 per minute, which is 11 times greater than that of pure MoO3 and far greater than that of the recently reported MoO3 nanostructures. This excellent selective adsorption performance of Fe–MoO3 NWs was mainly attributed to the enhanced chemical adsorption of quasi-phenothiazine dyes by rich surface –OH groups and Fe species through hydrogen bond and coordination bond adsorption with N and S, respectively, which was confirmed by adsorption isotherms and adsorption kinetics. These results suggest the potential application of Fe–MoO3 NWs in the field of water pollution treatment.

Cerium dioxide (CeO2) octahedra were synthesized by a facile microwave-assisted hydrothermal method. The structure and morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that octahedra were enclosed by eight (111) facets with an edge length of 180 nm. The possible growth mechanism of CeO2 octahedra was proposed by adjusting the reaction temperature, solvent, molar ratios of polyvinyl pyrrolidone (PVP)/Ce3+ and reaction time. The formation of the octahedra was attributed to the oxygen terminated structure of (111) facets and the steric hindrance effect of PVP. Furthermore, the catalytic activity of CeO2 octahedra on the thermal decomposition of ammonium perchlorate (AP) was investigated by thermogravimetry and differential scanning calorimetry (TG-DSC). Compared with cubes, the CeO2 octahedra exhibited enhanced activity on the decomposition of AP. Upon addition of 4 wt% CeO2 octahedra, the ending mass loss temperature of AP decreased by 52.1 °C. The higher catalytic activity was attributed to the synergistic effect between the exposed (111) facets and high concentration of oxygen vacancies that arised from the mixed valence state of Ce ions.

Nitrogen doping is an efficient strategy to improve the catalytic activity of carbocatalysts in direct dehydrogenation reactions. The interpretation of enhanced activity is now mainly attributed to the strengthened basicity. On the other side of doping, electronic properties that differed in various nitrogen doping configurations, however, were barely considered. Herein, to elucidate the role of graphitic N, pyridinic N and pyrrolic N, N-doped porous carbon balls with tunable contents of these nitrogen species were used as moulded carbocatalysts for steam-free direct dehydrogenation of ethylbenzene to styrene. Along with C O groups that were commonly certified as active sites on carbocatalysts, graphitic N contributes to the styrene yield. The former serves as active site that directly activates and dissociates C–H bond, while the latter one provides additional electrons into the delocalized π-system and leads to improved chemical reactivity of C O. The loss of C O active sites is not only attributed to the carbon deposition as illustrated by the elevated area ratio of D3 to G band in Raman spectra, but also its failed regeneration from intermediate hydroxyl groups (C–OH), which was proved by the tiny thermal decomposed products of CO and H2O as detected by the on-line mass spectrometry and gas chromatography.

Although significant progress has been made in WO3 hollow spheres, it is still a challenge to synthesize WO3·0.5H2O hollow spheres. Herein, a strategy for the preparation of well-shaped WO3·0.5H2O hollow spheres was developed by a facile bubble-template method using urea as a foaming agent in the solvothermal process with EtOH–H2O mixture solvent. In this process, the growth of WO3·0.5H2O nanoparticles is limited by N-containing organic compounds, thus these nanoparticles tend to agglomerate along the surface of bubbles (CO2 and NH3) to fabricate hollow spheres with pores formed in the wall, and after low temperature calcination, pure WO3·0.5H2O hollow spheres are obtained. The obtained WO3·0.5H2O hollow spheres exhibit enhanced activity in catalytic oxidation of benzyl alcohol to benzaldehyde: the conversions of benzyl alcohol, 4-methyl, 3-methyl, 2-methyl, 4-bromo and 4-nitro benzyl alcohol are 99.2%, 95.0%, 97.1%, 86.7%, 98.0%, 90.6%, respectively, and the selectivities to corresponding benzaldehydes are all greater than 98%. The high activity of WO3·0.5H2O hollow spheres could be attributed to surface –OH groups and the hollow and porous structure.

Hematite (α-Fe2O3) is regarded as one of the most promising photocatalysts, but its photocatalytic activities have always been limited to the pristine form because of poor charge separation efficiency. In the present work, a new kind of dodecahedral α-Fe2O3 particle (DoFe) enclosed by six (012) and six (104) facets provides us with a clue to solving this problem, because the coexistence of these two facets brings about a better photocatalytic performance than that for crystals exposing only a single facet. The results show that, in addition to surface structures, photogenerated charge separations between anisotropic facets also have an influence on photocatalytic activities. Furthermore, particle size could be precisely regulated, which is helpful for ruling out the possible specific contribution of edges and vertexes. These results are of great importance for our understanding of the relationship between morphology and activities, and can direct us to synthesize a high-efficiency catalyst.

High temperature carbonization, an important approach to cleanly and efficiently use coal, refers to a complex process in which a series of physical phenomena and chemical reactions occur when coal is heated to ≥1000 °C in anoxic conditions. A furnace was developed for the in-situ small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) measurements with the scattering angle 2θ between 0° and 60° during sample heating from room temperature to 1200 °C. The usefulness of the furnace for high temperature carbonization of coal was verified at the 1W2A SAXS station at the Beijing Synchrotron Radiation Facility (BSRF).

The development of efficient and low-cost hydrogen evolution reaction (HER) catalysts is critical for energy storage and conversion devices. Herein, we develop a facile method to fabricate a novel hybrid by in situ growing CoP porous nanoplates on reduced graphene oxide (RGO). The hybrid shows excellent HER performance in acid media with a low Tafel slope of 57 mV dec−1, small onset overpotential of 76 mV and long-term durability with 86.3% current density retention after 10 h electrocatalysis. The superb HER activity can be ascribed to the unique structure of porous hexagonal nanoplates. On the one hand, the porous structure provides abundant active sites for HER. On the other hand, hexagonal nanoplates provide large contact with RGO, enhancing the charge transfer ability. In addition, the hybrid with such structure shows good stability under ambient atmosphere and can maintain the initial HER activity even after six months of storage. This work demonstrates that large contact between active component and conductive support is not only beneficial to the HER activity and durability, but also beneficial to the stability of material itself.

Rational design of supported noble metal is of great importance for highly efficient heterogeneous catalysts. On the basis of the distinct adsorption characteristics of noble metal and transition-metal oxides toward O2 and CO, the overall catalytic performance of CO oxidation reaction could be further modified by controlling the surface property of the materials to achieve optimal adsorption activity. Here, we studied the influence of facets matching between both platinum and ferric oxide support on CO conversion efficiency. It shows that the activities of four catalysts rank following the order of Pt{100}/α-Fe2O3{104} > Pt{100}/α-Fe2O3{001} > Pt{111}/α-Fe2O3{001} > Pt{111}/α-Fe2O3{104}. The strong metal–support interaction and adsorption energy varying with matched enclosed surface are demonstrated by density functional theory based on the projected d-band density of states. Compared with the other three cases, the combination of Pt{100} and α-Fe2O3{104} successfully weakens CO poisoning and provides pro...

Rational design and optimization of metal-free electrocatalysts for the oxygen reduction reaction (ORR) is crucial for fuel cells and metal-air batteries. However, identifying design principle that links the active sites and their synergistic effects is far from satisfactory, especially for B,N-codoped graphene. Herein, we provide four B,N-codoped porous graphenes with tunable contents of pyridinic N, graphitic N, BC3 and C-B(N)O. BC3 shows multiple-fold specific activity compared with graphitic N and pyridinic N, while C-B(N)O offers no positive contribution. Density functional theory calculations indicate that the synergistic effect between graphitic N and BC3 can effectively facilitate the reduction of O2. These pinpoint that graphitic N and BC3 are the main active sites among various nitrogen or/and boron doping configurations. The most active catalyst exhibits superior activity than the commercial Pt/C catalyst using the RDE method in alkaline media, and displays comparable power density to Pt/C catalyst in Zn-air battery.

BN nanosheets (BN) have drawn great attention in heterogeneous catalysis recently, and their defects have a profound effect on the key performance of the catalyst, but it has been overseen and little addressed. Here, three Fe/BN nanosheet (Fe/BN) catalysts were prepared BN with varied B–O surface defects. Fischer–Tropsch synthesis, a key industrial process, was taken as an example. It is found that the rich B–O defects not only resulted in decreased crystal size and low crystallinity of the Fe2O3 but also showed enhanced interaction with the active component and support. As a consequence, the three Fe/BN catalysts showed a dramatic difference in catalytic performance. Our studies reported here could be a guide for the rational design of the highly efficient hydrogenation BN-based catalyst.

For most of WO 3 , a visible-light-driven photocatalyst, its barrier in photocatalytic degradation is the low conduction band (CB) potential that can not reduce O 2 to O 2 − and HO 2 radicals and thus results in fast recombination of electron/hole. With this in mind, a new active FeWO 4 /Fe 2 O 3 di-modified WO 3 was designed and prepared via by a straightforward but effective strategy by introducing of FeWO 4 and Fe 2 O 3 clusters (or nanoparticles) on WO 3 . The performance of di-modified WO 3 showed super high photocatalytic activity in degrading quasi-phenothiazine dyes of Methylene blue (MB), Toluidine blue (TB), Azure I (AI) and Acridine orange (AO) under visible light irradiation, and the corresponding k values are 5.3, 4.4, 3.8 and 5.8 times larger than that of pure WO 3 , respectively. This improvement was mainly due to the fact that photoexcited electrons can migrate to the matching CB of firmly and highly dispersed FeWO 4 and Fe 2 O 3 , then be consumed rapidly by a valence decrease from Fe 3+ to Fe 2+ and Fenton reaction between Fe 2+ and H 2 O 2 . And the strong adsorption of Fe species toward N and S (or N) elements in quasi-phenothiazine dyes, also positively promoted the efficiency of degradation.

Hexagonal boron nitride nanosheets (BNNSs), which show outstanding thermal conductivity and chemical stability, have drawn more and more attention in recent years. However, the limited yield, dispersivity and the polydispersed size of the exfoliated ones hinder their further application. Here, we present a method of effective and scalable synthesis of quasi-monodispersed BN colloidal nanocrystals by “solid-state synthesis” combined with “solvent cutting” technique. The key of the technique is the imperfect nitridation of the BO species, which yield the boron oxides and amorphous BN that coexist with the well crystallized BN domains. As the impurities that separate the well crystallized BN domains are removed, the BN skeleton with better crystallinity is remained. The BN colloidal nanocrystals are obtained when the solvents cut the weak grain boundary in BN skeleton. The lateral size of as-prepared BN colloidal nanocrystals could be well controlled for 3 nm, 10 nm and 20 nm. The zeta potentials of colloid are below −30 mV in a pH range of 5–12. That means the BN colloid can keep high colloidal stability over a wide pH range. As an exemplary application of colloidal BN nanocrystals, the BN film is coated on the copper foil by a simple dip-coating method. The coated copper foil shows remarkable anti-electrochemical corrosion property. This study not only paves a way for the synthesis of colloidal BN nanocrystals, but also gives an alternative choice for a facile and low cost protective BN coating.

Compared with mushroomed progress in metal-free C-rich BCN catalysts, little is known about the BN-rich BCN or even BN ones. Its related study has drawn great interest recently but still in its infancy stage. In this study, three kinds of BCN nanosheets (NSs) with tuned surface carbon contents (5.5–14.3%), specific surface area (SSA, 82–290 m2/g) and morphologies (ultrathin nanosheets, triangular plates) were fabricated through a solid state reaction by simply adjusting the reaction temperature, and those effects on the ethylbenzene dehydrogenation performances were studied in CO2 atmosphere. The morphology evolution of BCN NSs from ultrathin nanosheets to the triangular plates was observed and control experiments were carried out. The BCN nanosheets show relatively strong interaction with CO2 and distinct CO2 absorption properties. The CO2 temperature programmed desorption also indicates that the desorption peaks of CO2 are above 400 °C, enabling them potential CO2 utilization catalysts. A weak association was found between the surface C contents and the catalytic performance as it normalized with SSA, and the B-O species could be taken as an active site in CO2 atmosphere. Though much progress still needed, it is convincing that the BCN catalyst could be a promising metal-free catalyst in dehydrogenation beyond carbocatalyst.

A one-pot facile, impurity-free hydrothermal method to synthesize ultrathin α-FeOOH nanorods/graphene oxide (GO) composites is reported. It is directly synthesized from GO and iron acetate in water solution without inorganic or organic additives. XRD, Raman, FT-IR, XPS and TEM are used to characterize the samples. The nanorods in composites are single crystallite with an average diameter of 6 nm and an average length of 75 nm, which are significantly smaller than GO-free α-FeOOH nanorods. This can be attributed to the confinement effect and special electronic influence of GO. The influences of experimental conditions including reaction time and reactant concentration on the sizes of nanorods have been investigated. It reveals that the initial Fe2+ concentration and reaction time play an important role in the synthetic process. Furthermore, a possible nucleation-growth mechanism is proposed. As electrode materials for supercapacitors, the α-FeOOH nanorods/GO composite with 20% iron loading has the largest specific capacitance (127 F g−1 at 10 A g−1), excellent rate capability (100 F g−1 at 20 A g−1) and good cyclic performance (85% capacitance retention after 2000 cycles), which is much better than GO-free α-FeOOH nanorods. This unique structure results in rapid electrolyte ions diffusion, fast electron transport and high charging-discharging rate. In virtue of the superior electrochemical performance, the α-FeOOH nanorods/GO composite material has a promising application in high-performance supercapacitors.

The correlation between the catalytic activities and electrochemical features of MoSx material is important to study the work process of structure on catalytic performance. In this work, adopting the centimeter-scale ultra-thin MoSx film as a research model, we try to establish a persuasive electrochemical features–catalysis correlation in two different ultra-thin MoSx structures, of which one is O contaminated and another is O free. The results indicate that whatever the structure of MoSx is, high turnover frequency (TOF) and large cathodic current density (J) require low charge-transfer resistance (Rct); low over-potential (η) requires low charge-transfer resistance (Rct) and rich active sites; low Tafel slope requires the high activity of the active sites; and high exchange current densities (Jo) requires a match between the activity of the active sites and Rct. These results provide useful information for the further improvement of MoSx material. From the catalytic activities we can infer which parameters of the electrochemical features need to be improved, and then selectively adjust its physical structure.

Two kinds of 3D hierarchical α-Fe 2 O 3 nanoparticles, flower-like structure with the (0 0 1) plane predominantly exposed on petals and urchin-like structure with nanorods grown along [0 0 1] direction, have been synthesized under the influence of glycerol by a facile hydrothermal method. It is proposed that the Fe(III)–glycerol micro-reaction units that selectively adsorb to (0 0 1) or other planes result in different morphologies. The adsorption of Cr(VI) from aqueous solution onto these α-Fe 2 O 3 nanoparticles showed that the removal efficiency up to 98.5% and 88.8% in 25 mg/L Cr(VI) solution, and the adsorption capacity reaches to 34.4 mg/g and 26.0 mg/g without pH adjustment. The adsorption kinetic is well described by the pseudo-second-order model and the Cr(VI) adsorption on the adsorbent agrees well with the Langmuir model. Lower surface areas and more excellent adsorption property associates with the chemisorption of Cr(VI) onto α-Fe 2 O 3 (0 0 1), which is achieved by coordination between Cr(VI) and doubly or triply coordinated hydroxyl groups on α-Fe 2 O 3 surface.

Herein, tungsten oxide hexagonal prisms with a biphase of h-WO3 and o-WO3·0.33H2O were prepared by a facile hydrothermal method using Fe3+ cations. The combination of instrumental characterization and software simulation proved that two phases coexisted in one nanoparticle with same morphology. The ratio of two phases could be changed by adjusting the concentration of Fe3+ cations. On the basis of controlled experiments, a mechanism was proposed to illustrate the formation of this biphase WO3 structure, and it was also proved that the self-growth of Fe species was unfavorable for the coexistence of two phases.

The replacement of superheated steam with CO 2 for ethylbenzene (EB) dehydrogenation to produce styrene (ST) is of great importance from both scientific and practical perspectives, while it is still a big challenge to design and synthesize catalysts for dehydrogenation in the presence of CO 2 . Research into shape-controlled nanocrystals has proved that well-defined facets are of great importance for understanding the catalytic phenomena due to their definite surface structure. In the present work, α-Fe 2 O 3 nanocrystals enclosed by various crystal facets provide us the clue to understand the role of CO 2 in dehydrogenation. O(III) (the triply coordinated surface oxygen atom) is found to play an important role in activating CO 2 under reaction conditions, which is supported by both experimental and theoretical results. These results have deepened knowledge about the role of CO 2 in dehydrogenation over pure α-Fe 2 O 3 catalysts, which is significant in designing relative catalysts rationally.

Nitrogen-doped graphene is a promising candidate for the replacement of noble metal-based electrocatalysts for oxygen reduction reactions (ORRs). The addition of pores and holes into nitrogen-doped graphene enhances the ORR activity by introducing abundant exposed edges, accelerating mass transfer, and impeding aggregation of the graphene sheets. Herein, we present a straightforward but effective strategy for generating porous holey nitrogen-doped graphene (PHNG) via the pyrolysis of urea and magnesium acetate tetrahydrate. Due to the combined effects of the in situ generated gases and MgO nanoparticles, the synthesized PHNGs featured not only numerous out-of-plane pores among the crumpled graphene sheets, but also interpenetrated nanoscale (5–15 nm) holes in the assembled graphene. Moreover, the nitrogen doping configurations of PHNG were optimized by post-thermal treatments at different temperatures. It was found that the overall content of pyridinic and quaternary nitrogen positively correlates with the ORR activity; in particular, pyridinic nitrogen generates the most desirable characteristics for the ORR. This work reveals new routes for the synthesis of PHNG-based materials and elucidates the contributions of various nitrogen species to ORRs.

As electromagnetic pollution is becoming more and more serious, novel composite microwave absorbents are gaining much attention. In this work, low-cost glucose was used as a carbon source to prepare hydrochar, and Fe–Fe3C/C microspheres for microwave absorption were successfully synthesized through the hydrothermal synthesis of Fe3O4/hydrochar and subsequent high-temperature carbonization at different temperatures. The results showed that the Fe–Fe3C nanoparticles were uniformly loaded on the carbon microspheres. Resulting from the synergistic effect of Fe–Fe3C nanoparticles and partially graphitized carbon, a wide region of microwave absorption was achieved due to dual dielectric and magnetic losses. An effective bandwidth of reflection loss less than −10 dB could reach up to 4 GHz with 1.5 mm thickness. Owing to the characteristics of the cost-effective synthetic route, low density and good microwave absorption with thin thickness, the Fe–Fe3C/C microspheres could be used as a lightweight and highly efficient microwave absorbent.

A series of Co3O4 nanocrystals with systematic shape evolution from octahedra to corner-truncated octahedra, corner-truncated cubes, globate polyhedra and micro-spheres were successfully synthesized under the influence of C2O42− and PVP. It was proved that crystal facet growth limitation caused by the adsorption of C2O42− and PVP on the surface of Co3O4 particles played a crucial role in this shape evolution process. Besides obtaining a series of intermediate Co3O4 nanocrystals exposing different facets, this strategy could also show the relationship between these structures. The present work extends the PVP-assisted method to realize the shape evolution process of metal oxide nanomaterials.

Co3O4 microparticles, with many smooth quadrihedrons on the surface, were hydrothermally synthesized under the influence of EDTA2− anions. Due to the excellent chelating and capping ability of EDTA2−, the as-obtained Co3O4 microparticles were mainly enclosed by (111) and (113) facets or their equivalent facets. On the basis of condition-dependent experiments, a dehydration condensation reaction assisted by the limitation effects of EDTA2− adsorbed on the surfaces of Co3O4 was proposed to explain the growth process of the cubic crystalline Co3O4 microparticles. The as-obtained Co3O4 microparticles could catalyze the thermal decomposition of ammonium perchlorate (AP) effectively due to the exposure of the high energy facets.

The boron nitride nanosheets (BNNSs) have attracted great interest in the field of energy storage and heterogeneous catalysis. In this paper, BNNSs supported iron (Fe/BNNSs) catalysts were prepared by one-pot solid state reaction and used in Fischer–Tropsch synthesis (FTS) for the first time. The microscopic structure, morphology and metal–support interaction of the Fe/BNNSs catalysts were investigated by TEM, FT-IR, 1H MAS NMR and H2-TPR. The average thickness of the N-rich BNNSs support was 4–8 nm, and the mean size of the iron nanoparticles was 25–40 nm. The CO conversion, CH4 and C5+ selectivity of typical Fe/BNNSs catalyst with 33 wt% Fe-loading were 47%, 13.7% and 48% at 270 °C, respectively. No obvious deactivation was observed even after 270 h running. The conversion, selectivity and the iron time yield (FTY) of Fe/BNNSs catalysts were highly related to the loading, dispersion of iron nanoparticles. The lower loading and better dispersion of the iron nanoparticles in Fe/BNNSs catalyst resulted in the better FTY and C5+ selectivity. The N-rich defects of BNNSs and porous structure of BNNSs anchored active phases to prevent them from growing larger. Therefore, the BNNSs support plays an important role in retarding the catalyst from deactivation.

Despite the significant progress in making hollow structures, it is still a challenge to synthesize some specialized hollow structures. In the present work, we obtained a new hollow hematite structure, tube-in-dodecahedron, by using the stepwise influences of fluoride and phosphate anions. Based on condition-dependent experiments, we proposed a “nucleation–aggregation–recrystallition and etching” mechanism, which also directed us to synthesize a series of hematite hollow structures, including hollow dodecahedron and hollow ellipsoid. The concentration of phosphate was found to play a decisive role in the control of these hollow structures. 0.08 mM is the critical point for keeping the top facets of dodecahedral hematite particles while 0.2 mM is the upper limit for keeping the lateral facets. The magnetic properties of these synthesized hollow hematite structures were found to be closely associated with the structures. The synthesized tube-in-dodecahedral hematite particles exhibited excellent photocatalytic reactivity toward organic dyes.

Ni modified MoO3 (Ni-MoO3) had been synthesized by a facile one-step hydrothermal technique and was used for oxidative desulfurization (ODS) of dibenzothiophene (DBT) in the decalin/acetonitrile biphasic system with H2O2 as oxidant, the effect of different operating conditions was investigated. Under the optimal reaction condition, Ni-MoO3 catalyst showed excellent ODS performance toward DBT, the highest sulfur removal efficiency can be up to 99.8% and sulfur content was wiped out from 5000 to 10 ppm, which is more effective than the recent reported MoO3-based catalysts. The reaction kinetics obeyed the pseudo-first-order equation with an apparent rate constant of 0.076 min−1, which is twice that of pure MoO3 (0.035 min−1). The ODS mechanism of DBT with Ni-MoO3 was explored by combining radical scavenger, FT-IR experiments and theoretical analysis, proving that surface oxygen vacancies and Lewis acid sites play important roles in the high-efficiency ODS reaction with Ni-MoO3 catalyst.

In this work, we demonstrated a facile template-free method for the preparation of hollow CuO microspheres via a conventional hydrothermal reaction. The hollow architecture formed directly during the hydrothermal treatment of copper nitrate and glucose, without the use of template, precipitant and calcination process. The effects of reaction time, reaction temperature and glucose concentration were investigated in detail. On the basis of experimental results, the formation of hollow CuO microspheres probably proceeded via self-assemble process and the subsequent Ostwald's ripening. This synthetic strategy strongly depended on the characteristics of copper nitrate, which made it could not extend to other copper salts and/or nitrates. Even though, glucose still showed efficient morphology controlling ability with respect to nanosized transitional metal oxides, which could be used for the controllable synthesis of nanomaterials.

A small sample stretcher for in-situ measurement of small angle X-ray scattering (SAXS) was developed, which consists of stretch, transmission, detection and control systems. The basic parameters of the stretcher are: tension ≥ 400 N, 3 mm/min ≤ stretching speed ≤ 50 mm/min, sample length ≤ 30 mm, stroke ≥ 80 mm, and resolution = 50 μm. The stretcher is compact and has low stretching speed and convenient remote control. It is suitable for in-situ SAXS measurements on stretching of carbon fibers, polyethylene and other samples. Such measurement were carried out with high density polyethylene (HDPE) on the SAXS instrument at the 1W2A station of Beijing Synchrotron Radiation Facility (BSRF). The result verified the effectiveness of the stretcher.

Plasma equilibrium reconstruction plays an important role in the tokamak plasma research. With a high temporal and spatial resolution, the POlarimeter-INTerferometer (POINT) system on EAST has provided effective measurements for 102s H-mode operation. Based on internal Faraday rotation measurements provided by the POINT system, the equilibrium reconstruction with a more accurate core current profile constraint has been demonstrated successfully on EAST. Combining other experimental diagnostics and external magnetic fields measurement, the kinetic equilibrium has also been reconstructed on EAST. Take the pressure and edge current information from kinetic EFIT into the equilibrium reconstruction with Faraday rotation constraint, the new equilibrium reconstruction not only provides a more accurate internal current profile but also contains edge current and pressure information. One time slice result using new kinetic equilibrium reconstruction with POINT data constraints is demonstrated in this paper and the result shows there is a reversed shear of q profile and the pressure profile is also contained. The new improved equilibrium reconstruction is greatly helpful to the future theoretical analysis.