The Y2Si4N6C:Ce3+ carbidonitride phosphor has been successfully synthesized via a novel acid-driven carbonization and carbothermal reduction nitridation method (ADC–CRN). This novel approach for Y2Si4N6C:Ce3+ promises lower heating temperature and shorter heating time than classical methods, indicative of a cost-effective and facile way to search for new silicon-based carbidonitrides. In contrast to Ce3+ activated (oxy)nitrides showing blue-green emissions, Y2Si4N6C:Ce3+ exhibits an individual green-yellowish emission band centered at 550 nm which is ascribed to the incorporation of highly covalent C4− into the host lattice. The sp3 hybrid C4− was identified through high resolution electron energy loss spectroscopy analysis (EELS). Direct evidence for sole substitution of Ce3+ for Y3+ in Y2Si4N6C is represented for the first time using electron paramagnetic resonance (EPR) spectra. The red shift induced by the increasing Ce3+ content in Y2Si4N6C is reasonably deduced by the energy transfer model of intra-Ce3+ and inter-Ce3+ ions. A pc-w-LED packaging was fabricated via a combination of the yellow Y2Si4N6C:Ce3+ and blue La2Si4N6C:Ce3+ phosphors prepared using a 365 nm n-UV chip. The w-LED device shows a good color rendering index (Ra), CIE chromaticity coordinates and correlated color temperature (CCT) of 83.8, (0.3258, 0.3314) and 5819 K, respectively. These results suggest that Y2Si4N6C:Ce3+ has great potential for use in UV-LED-driven white emitting diodes.

Gd2Si2O7:Ce (GPS:Ce) and (Gd,La)2Si2O7:Ce (La-GPS:Ce) phosphors with different crystal structures, tetragonal, orthorhombic and triclinic, were synthesized via a sol–gel technique. The prepared samples have been systematically investigated using room temperature (RT) XRD, high temperature (HT) XRD, HRTEM, selected area electron diffraction (SAED) and EDS elemental analysis. The results show that the phase transition occurred at 1350–1450 °C and the tetragonal phase was a low-temperature metastable phase and the orthorhombic and triclinic structures were stable at high temperatures. It was observed that the three structures display completely different luminescence efficiencies under both UV lamp and X-ray excitation, but the decay time was not strongly dependent on the crystal structure. The luminescence thermo-stability and activation energy were also measured and calculated. The results indicate that the thermo-stability was strongly dependent on the crystal structure and the GPS:Ce-1500 °C sample showed the best thermo-stability. The three materials have potential application as a novel type of scintillator.

A new Eu2+ activated, G-type La2Si2O7 phosphor was synthesized successfully via a novel SiC-reduction route. The valence state of the Eu2+ ions was identified with XRD and XPS analysis and the luminescence spectrum presented Eu2+ broad bands. The G-La2Si2O7:Eu2+ (LPS:Eu2+) phosphor exhibited tunable emission colors depending on the excitation wavelength or the Eu concentration, enabling the production of white light. The color tunable property is ascribed to the component ratio of the two specific luminescent centers, Eu(1) and Eu(2). Eu2+ ions prefer to occupy the La3+ crystallographic sites selectively, which was identified by electron paramagnetic resonance (EPR) spectroscopy. Furthermore, the relative emission intensity of the phosphor at 100 °C and 160 °C can maintain 89% and 76% of the value measured at room temperature, which is much better than that of most of Eu2+ doped silicon oxides phosphors. The Eu(1) emission possesses a better fluorescence thermal stability than the Eu(2) emission, and an energy transition from Eu(1) to Eu(2) occurs. This better thermal stability and energy transition have been explained by the schematic configuration coordination. A w-LED device was fabricated by combining the prepared La2Si2O7:Eu2+ and commercial BaMgAl10O17:Eu2+ phosphors with a 365 nm n-UV chip. The w-LED device generates white light (color rendering index Ra = 93.9), and its CIE chromaticity coordinates and correlated color temperature (CCT) are (x, y) = (0.3429, 0.3523) and 5090 K, respectively. These results suggest that LPS:Eu2+ has a great potential for use in UV-LED-driven white emitting diodes.

•N-doped carbon nanotubes (NCNTs) are prepared by pyrolysis of Co2+@g-C3N4.•Ultrafine Pt nanoparticles grow onto the NCNTs.•Pt/NCNTs with ultralow-Pt-loading show high hydrogen evolution activity.•Addition of mesoporous silica to the electrode could improve the activity.The highly effective catalysts for the electrochemical hydrogen generation with substantially reduced cost are strongly desirable, but difficult to achieve. The reduction of Pt-loading by downsizing the Pt nanoparticles is an efficient strategy for obtaining low-cost and high-activity HER electrocatalysts. Herein, we describe a facile strategy to the formation of ultrafine Pt nanoparticles (NPs) bonding to N-doped bamboo-like carbon nanotubes, serving as a highly active and durable catalyst with ultra-low Pt loading for the electrochemical hydrogen generation. With the addition of mesoporous silica to change the wettability of the electrode from hydrophobicity to hydrophilicity of the electrode, the optimized nanocomposite catalyst with ultra-low Pt loading (0.74 wt%) shows a near-zero onset potential (Uonset), an extremely low overpotential of 40 mV to reach 10 mA cm−2 (η10), a small Tafel slope of 33 mV dec−1, and excellent long-term stability, which are comparable to those of 20 wt% Pt/C catalyst. The outstanding properties ensure this promising nanocomposite with significantly reduced Pt loading to become one of the most active catalysts towards the electrochemical hydrogen generation in acid medium.The facile formation of ultrafine Pt nanoparticles bonding to bamboo-like CNTs with structural defects and N-dopants can bring a new class of ultra-low Pt-loading nanocomposites, functioning as highly active and stable hydrogen-evolving electrocatalysts in acidic electrolyte compared to commercial 20 wt% Pt/C catalyst.Download high-res image (337KB)Download full-size image

The development of efficient non-precious-metal electrocatalysts towards the hydrogen evolution reaction (HER), with superior activity and stability, remains a great challenge in the area of renewable energy. In this work, we demonstrated a facile, one-step protocol to synthesize ultrathin graphitic layer (GL)-encapsulated ultrafine ditungsten carbide (W2C) nanoparticles (W2C@GL) with sizes smaller than 10 nm, exhibiting a superior HER activity in acidic solution. An efficient W2C phase, along with an improved electron transfer process by GL wrapping, cooperatively leads to a small Tafel slope of 68 mV dec−1 and a large exchange current density of 0.24 mA cm−2 for W2C@GL, which exceeds the previous W2C materials by far. Over 91% of the current density is maintained after over 8 h of operation, which indicates a good stability of this hybrid catalyst. Thus, W2C@GL with these excellent properties has been among the best non-noble metal HER electrocatalyst reported to date.

Polyacrylonitrile (PAN)-based carbon nanofibers prepared by electrospinning were physically activated using carbon dioxide as the oxidizing agent. The activation procedure was performed at 800 °C for different periods of time ranging from 15 to 60 min. The activated materials have a hierarchical structure with two sets of pore systems in the micropore range centered at ∼0.8 nm and small mesopore range centered at ∼2.8 nm. The activation not only increased the specific surface area and pore volume to 1123 m2 g−1 and 0.64 cm3 g−1, respectively, but also resulted in the evident loss of doped N atoms. The pyridinic and graphitic nitrogen groups are dominant among various N functional groups in the activated samples. CACNF-60, prepared by activating the carbon nanofibers (CNFs) for 60 min, showed excellent electrocatalytic activity for the oxygen reduction reaction (ORR) as well as superior long-term stability and methanol tolerance compared to commercial Pt/C in alkaline media. The excellent electrocatalytic activity of the activated sample is mainly due to its high N content (6.9 at%), unique hierarchical micro-/mesoporosity, and large specific surface area.

Dual-doped graphene is synthesized by a facile solvothermal method with the assistance of ionic liquids containing both N and X (X = B, P or S) atoms. All three types of co-doped graphene present excellent catalytic activity, demonstrating preferred four-electron selectivity and low peroxide yields toward oxygen reduction reaction in alkaline solution. Particularly, N, P-graphene exhibits superior catalytic activity to its counterparts in terms of half-wave potential (ΔE1/2 = −70 mV relative to commercial Pt/C), methanol tolerance and long-term stability. This could be attributed to the unique porous nanostructure, change of charge density and high distortion of carbon structures originating from the combination of large electronegativity of N element and big covalent radius of P atoms.

•MnF2 rods and hierarchical CoF2 cuboids were synthesized by the assistance of ionic liquid.•The as-prepared submicro-/nano-sized MnF2 and CoF2 particles exhibit remarkable capacitance.•The cycled electrodes were investigated by different characterization techniques.•The mechanism can be ascribed to the redox reactions between MnF2/CoF2 and MnOOH/CoOOH.Submicro-/nano-sized MnF2 rods and hierarchical CoF2 cuboids are respectively synthesized via a facile precipitation method assisted by ionic liquid under a mild condition. The as-prepared MF2 (M = Mn, Co) submicro/nanoparticles exhibit impressive specific capacitance in 1.0 M KOH aqueous solution, especially at relatively high current densities, e.g. 91.2, 68.7 and 56.4 F g−1 for MnF2, and 81.7, 70.6 and 63.0 F g−1 for CoF2 at 5, 8 and 10 A g−1, respectively. The mechanism of striking capacitance of MF2 is clarified on the basis of analysing the cycled electrodes by different characterization techniques. Such remarkable capacitance is ascribed to the redox reactions between MF2 and MOOH in aqueous alkaline electrolytes, which can not be obtained in aqueous neutral electrolytes. This study for the first time provides direct evidences on the pseudocapacitance mechanism of MF2 in alkaline electrolytes and paves the way of application of transition metal fluorides as electrodes in supercapacitors.Transition metal difluorides (e.g. MnF2 rods) were prepared with the assistance of ionic liquid, exhibiting remarkable pseudocapacitive performance in 1.0 M KOH aqueous electrolyte.

N-doped graphene-wrapped carbon nanoparticles (NGCNPs) are in situ synthesized by a facile bottom-up method. The heat treatment boosts the conversion of N-containing species from the pyrollic N to graphitic N and pyridinic N, thus improving the electrocatalytic activity towards the oxygen reduction reaction (ORR). The physical characterization including X-ray photoelectron spectroscopy, Raman spectra, specific surface area and charge transfer resistance indicates that 600 °C is a pivotal temperature for remarkably improving the electrochemical activity for ORR in terms of onset potential, half-wave potential, electron transfer number and peroxide yields.

•Eu2+ doped b-SiAlON blue luminescent fibers were successfully prepared.•Use of electrospinning with carbothermal reduction nitridation.•Sucrose was utilized as carbon source to effectively form β-SiAlON:Eu2+.•Active carbon powders were covered on fiber precursor layers during processing.•Produced fibers own smooth surface and uniform morphology.β-SiAlON:Eu2+ phosphors synthesis usually requires higher temperatures and higher nitrogen pressure conditions. In the present research, a low temperature technique has been developed to synthesize both β-SiAlON and Eu-doped β-SiAlON fibers by electrospinning combined with carbothermal reduction nitridation (CRN). The carbon sources used as reductant in CRN procedure have been optimized to effectively produce a well-crystallized β-SiAlON phase at lower temperatures of 1370–1500 °C. Additionally, through adding sucrose and covering activated carbon powders on the top of fiber precursor layers, the highly-pure β-SiAlON and β-SiAlON:Eu2+ fibers could be obtained. The pyrolysis behavior of fiber precursors, crystalline phase, morphology, and UV excited luminescence properties of the produced ceramic fibers were also studied by using TG–DSC measurement, XRD analysis, SEM observation, and spectrometer method. The resultant fibers exhibit a smooth surface and an uniforme morphology with a substantial length. Moreover, the β-SiAlON:Eu2+ fibers thus prepared show a blue light emission peaked at 470 nm under UV excitation.

•The glasses with starting composition of 30SiO2−70PbF2−xAgNO3 were prepared.•The Ag nanoclusters were spontaneously created in the glass during its casting.•The Ag nanoclusters doped glass can emit broad band green-yellow light.•The Ag nanoclusters doped glass owns a fast decay time of 2.1 ns.•The Ag nanoclusters are effectively protected and stabilized by the glass.Luminescent Ag nanoclusters doped solid host, such as glass, are very promising new materials for lighting applications due to their good mechanical and optical properties. In the present work, transparent Ag nanoclusters doped oxyfluoride amorphous glasses, having starting composition of 30SiO2–70PbF2–xAgNO3 (x=0, 0.5, 3 mol%), were prepared using melt quenching technique. The Ag nanoclusters are spontaneously created during the casting of glass. The prepared Ag nanoclusters doped glasses emit green-yellow light under exposure to UV lamp (λex=365 nm). The emission spectra of Ag nanoclusters doped glass show a red shift with the increase of excitation wavelength, and the excitation spectra show a similar red shift, that comes from Ag nanoclusters with different sizes and different local surroundings. The decay time of the Ag nanoclusters doped glass detected at the optimum wavelength (λex=370 nm, λem=530 nm) is only 2.1 ns, which may be attributed to the spin allowed singlet–singlet transitions of Ag42+ tetramers. High temperature photoluminescence spectra of the glass (x=3) show a slight decrease in luminescence intensity with the increase of temperature, and the luminescence intensity at 80 °C is about 60% of that at 25 °C. The Ag nanoclusters were effectively protected and stabilized by the 30SiO2–70PbF2 glass host.

Cobalt monoxide (CoO) nanoparticles (NPs) and mesoporous carbon (MC) with large specific surface area were combined as a novel nanocomposite (CoO/MC) using a hydrothermal method to reveal outstanding electrocatalytic activity in the oxygen reduction reaction (ORR). The addition of polyvinylpyrrolidone (PVP) as the surfactant during the hydrothermal process is beneficial for the high dispersion of CoO NPs on the surface of MC. Among the as-acquired products, the CoO/MC nanocomposite prepared with 1.5 g PVP as the surfactant (CoO/MC-1.5) exhibits much better catalytic activity for the ORR with a more positive onset potential, a highly efficient four-electron transfer pathway and a larger current density than the others. Furthermore, the CoO/MC-1.5 nanocomposite demonstrates outstanding durability based on current–time chronoamperometric tests, which significantly prevails over a commercial Pt/C catalyst. The eminent catalytic activities of the CoO/MC-1.5 nanocomposite should be a result of the synergistic effect of the highly dispersed CoO nanoparticles and the ordered mesostructures with large specific surface area, which are advantageous for increasing the exposure of the active sites and promoting fast transfer of the reactants and products.

The lack of efficient electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) has been a fatal issue for the development of metal–air batteries in large-scale commercialization. In this paper, spinel CoFe2O4 (CFO) nanoparticles were successfully in situ grown onto rod-like ordered mesoporous carbon (RC) by a facile, scalable hydrothermal method, followed by annealing at different temperatures. The as-acquired CFO/RC nanohybrid pyrolyzed at 400 °C (CFO/RC-400) has a high specific surface area (150.3 m2 g−1) and two sets of uniform mesopore systems (3.38 and 19.1 nm), all of which are favorable for the improvement of the electrocatalytic activity. The hybridization of CFO nanoparticles and the RC matrix results in increased ORR and OER electrocatalytic activity of the CFO/RC nanohybrids, which is significantly superior to that of unsupported CFO nanoparticles and pure RC. CFO/RC-400 shows better catalytic activity for the ORR with a direct four-electron reaction pathway than those prepared at other temperatures in terms of the onset potential and limiting current density. Furthermore, the CFO/RC-400 nanohybrid exhibits outstanding durability for both the ORR and OER, and can outperform commercial Pt/C. The excellent bifunctional electrocatalytic activities of the CFO/RC nanohybrids are mainly owing to the hierarchical mesoporous structures of the nanohybrids and strong coupling between the CFO nanoparticles and the RC matrix.

A series of novel nitrogen-doped hierarchical carbon monoliths (NCMs) with macroporous scaffolds composed of interconnected mesoporous rods were prepared successfully by a facile nanocasting strategy in combination with pyrolysis in a NH3 atmosphere. After etching off the hard template, the resulting NCMs had large macroporosity (up to 37.4 mL g−1) as well as large specific surface areas (1100–1600 m2 g−1), mesopore volumes (1.4–1.9 mL g−1), and narrow mesopore size distributions (3.8 nm). The nitrogen contents of the NCMs decreased from 4.7 to 1.6 at% with increasing pyrolysis temperature from 650 to 1050 °C. The pyridinic and graphitic nitrogen groups are dominant among various nitrogen-containing groups in the NCMs. Combined with their relatively high nitrogen-doping and unique hierarchical porous textures, NCM-750 exhibited comparable catalytic activity but superior long-term durability and methanol tolerance to commercial Pt/C for oxygen reduction reaction (ORR) with a four-electron transfer pathway in alkaline media. These excellent properties in combination with good recyclability and stability make these NCMs among the most promising electrocatalysts reported so far for efficient ORR in practical applications.

A series of magnetic γ-Fe2O3, Fe3O4, and Fe nanoparticles have been successfully introduced into the mesochannels of ordered mesoporous carbons by the combination of the impregnation of iron salt precursors and then in situ hydrolysis, pyrolysis and reduction processes. The magnetic nanoparticles are uniformly dispersed and confined within the mesopores of mesoporous carbons. Although the as-prepared magnetic mesoporous carbon composites have high contents of magnetic components, they still possess very high specific surface areas and pore volumes. The magnetic hysteresis loops measurements indicate that the magnetic constituents are poorly-crystalline nanoparticles and their saturation magnetization is evidently smaller than bulky magnetic materials. The confinement of magnetic nanoparticles within the mesopores of mesoporous carbons results in the decrease of the complex permittivity and the increase of the complex permeability of the magnetic nanocomposites. The maximum reflection loss (RL) values of −32 dB at 11.3 GHz and a broad absorption band (over 2 GHz) with RL values <−10 dB are obtained for 10-Fe3O4–CMK-3 and 10-γ-Fe2O3–CMK-3 composites in a frequency range of 8.2–12.4 GHz (X-band), showing their great potentials in microwave absorption. This research opens a new method and idea for developing novel magnetic mesoporous carbon composites as high-performance microwave absorbing materials.

It is of great concern to explore new electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this study, spinel NiFe2O4 nanoparticles cross-linked with the outer walls of multiwalled carbon nanotubes (MWCNTs) were successfully prepared by a simple, scalable hydrothermal method. The as-synthesized NiFe2O4/MWCNT nanohybrid shows not only a better ORR catalytic activity than pure NiFe2O4 and MWCNTs, but also a close four-electron reaction pathway. Meanwhile, the NiFe2O4/MWCNT nanohybrid exhibits a much higher OER catalytic activity when compared to NiFe2O4, MWCNTs and commercial Pt/C in terms of the onset potential and current density. Moreover, the NiFe2O4/MWCNT nanohybrid demonstrates the preeminent long-term durability measured by the current–time chronoamperometric test for both the ORR and OER, which evidently outperforms commercial Pt/C. The excellent bi-functional electrocatalytic activities of the NiFe2O4/MWCNT nanohybrid are attributed to the strong coupling between the NiFe2O4 nanoparticles and the MWCNTs as well as the network structure.

The production of efficient and low-cost electrocatalysts for the oxygen reduction reaction (ORR) is one of the key issues for the extensive commercialization of fuel cells. In this paper, we describe a facile one-pot hydrothermal synthesis route to in situ grow spinel NiFe2O4 nanoparticles onto the graphene nanosheets which were produced in advance by a scalable solvothermal reduction of chloromethane and metallic potassium. The resultant NiFe2O4/graphene nanohybrid exhibits superior electrocatalytic activity for the ORR to pure graphene nanosheets and unsupported NiFe2O4 nanoparticles, which mainly favours a desirable direct 4e− reaction pathway during the ORR process. Meanwhile, the NiFe2O4/graphene nanohybrid exhibits the outstanding long-term stability for the ORR, outperforming the commercial 20 wt% Pt/C based on the current–time chronoamperometric test. The excellent catalytic activity and stability of NiFe2O4/graphene nanohybrid are ascribed to the strong coupling and synergistic effect between NiFe2O4 nanoparticles and graphene nanosheets.

Phosphors with direct white light emission have been successfully found in the rare earth doped bismuth silicate systems, Bi4(1−x)Si3O12(BSO):RE4x3+ (RE3+ = Eu3+, Dy3+), using a fast combinatorial design and screening method. The material libraries were synthesized by ink-jetting precursor solutions into microreactor wells and sintering at high temperatures. The candidate compositions of the white light phosphors with varied dopant concentrations were evaluated by screening the recorded luminescence pictures under UV light excitation. The optimal compositions showing white light emission were further confirmed to be Bi3.96Si3O12:Eu0.043+ and Bi3.84Si3O12:Dy0.163+ via scale-up experiments. Additionally, the CIE chromaticity coordinate of the white light emission is located at (0.333, 0.326) for the optimal Bi3.96Si3O12:Eu0.043+ and the CIE coordinate of the Bi3.84Si3O12:Dy0.163+ phosphor is located at (0.302, 0.333), which are both very close to the CIE coordinate of soft sunlight (0.330, 0.330) and good for human eyesight. For the BSO:RE3+ (RE3+ = Eu3+, Dy3+) samples, the generation of direct white light emission can be realized by properly controlling the amount of doped RE3+ ions. It has been concluded that the white light emission directly results from a self-color-mixing mechanism of intrinsic host luminescence and doping ion luminescence. Besides that, the luminescence properties, energy transfer mechanism, and decay time of the direct white light phosphors have been discussed to set up a close relationship between the doping compositions and luminescence characteristics of the BSO:RE3+ (RE3+ = Eu3+, Dy3+) phosphors.

A combinatorial method was employed to rapidly screen the effects of La, Ce-co-doping on the luminescent properties of Gd2Si2O7 pyrosilicate using an 8 × 8 library. The candidate formulations (Gd1–x–yLax)2Si2O7:Ce2y were evaluated by luminescence pictures under ultraviolet excitation. The optimal composition was found to be (Gd0.89La0.1)2Si2O7:Ce0.02 after scaled-up preparation and detailed characterization of powder samples, which shows an excellent light output under both ultraviolet and X-ray excitation (about 5.43 times of commercial YAG:Ce powders). The XRD results indicate that the phase structure sequence is tetragonal–orthorhombic–triclinic for different calcination temperatures and doping ions. The (Gd0.89La0.1)2Si2O7:Ce0.02 powder sample also demonstrated excellent temperature stability of luminescence up to 200 °C and a short decay time of several tens of nanoseconds, suggesting that this may represent a new kind of scintillation material, such as single crystals, ceramics, glass, or phosphors.Keywords: ceramic phosphors; combinatorial screening; inkjet printing; luminescence; thermo-stability

Hierarchical porous activated carbons (ACs) were prepared via a chemical activation procedure with sustainable, renewable biomass fungi as carbon precursor and KOH as activating reagent. The as-produced porous ACs present not only a hierarchical porous structure containing macroporous frameworks and microporous textures, but also a high specific surface area of up to 2264 m2 g−1, a large pore volume of up to 1.02 cm3 g−1, and adjustable heteroatom doping (nitrogen: 2.15–4.75 wt%; oxygen: 8.53–14.48 wt%). The microstructural features can be easily controlled by adjusting the mass ratio of KOH/carbon precursor. The porous ACs possess a specific capacitance of up to 158 F g−1 in organic electrolyte, which significantly outperforms the commercially available ACs. The fungi-based ACs electrode also retains 93% of the specific capacitance as the current density increases from 0.1 to 5 A g−1, and has superior cycling performance (92% retention after 10000 cycles).

A series of microporous carbons (MPCs) were successfully prepared by an efficient one-step condensation and activation strategy using commercially available dialdehyde and diamine as carbon sources. The resulting MPCs have large surface areas (up to 1881 m2 g−1), micropore volumes (up to 0.78 cm3 g−1), and narrow micropore size distributions (0.7–1.1 nm). The CO2 uptakes of the MPCs prepared at high temperatures (700–750 °C) are higher than those prepared under mild conditions (600–650 °C), because the former samples possess optimal micropore sizes (0.7–0.8 nm) that are highly suitable for CO2 capture due to enhanced adsorbate–adsorbent interactions. At 1 bar, MPC-750 prepared at 750 °C demonstrates the best CO2 capture performance and can efficiently adsorb CO2 molecules at 2.86 mmol g−1 and 4.92 mmol g−1 at 25 and 0 °C, respectively. In particular, the MPCs with optimal micropore sizes (0.7–0.8 nm) have extremely high CO2/N2 adsorption ratios (47 and 52 at 25 and 0 °C, respectively) at 1 bar, and initial CO2/N2 adsorption selectivities of up to 81 and 119 at 25 °C and 0 °C, respectively, which are far superior to previously reported values for various porous solids. These excellent results, combined with good adsorption capacities and efficient regeneration/recyclability, make these carbons amongst the most promising sorbents reported so far for selective CO2 adsorption in practical applications.

A chemical processing method has been developed for preparing the nanosized phosphors of Lu2Si2O7:Ce3+ (LPS:Ce) by choosing mesoporous template SBA-15 as Si source. Accordingly, the luminescent ceramic composite of SiO2/LPS:Ce has also been densified by hot pressing at elevated temperatures using composited powders with the prepared LPS:Ce phosphor particles embedded in SiO2 matrix. XRD analysis and TEM observation have been carried out for both the prepared LPS:Ce phosphors and the final SiO2/LPS:Ce ceramics, indicating complete crystallization and a well distribution of LPS:Ce nanoparticles in SiO2 component. The ultra-violet fluorescence spectra, X-ray excited luminescence spectra, and decay time of the resultant SiO2/LPS:Ce ceramic composite have also been measured, showing a blue emission from Ce3+ and a fast decay time of about 37 ns. Experimental results show that an attractive strategy has been successfully developed for producing translucent or even transparent ceramics with phosphor nanoparticles embedded in matrix. The specific route can provide an effective control of reaction channels and a uniform distribution of phosphor particles in matrix by the template guiding role from ordered mesoporous SiO2. The fabrication method thus developed could be employed in other kinds of composited ceramics.

A covalent route has been successfully utilized for the surface modification of ordered mesoporous carbon (OMC) CMK-3 by in situ polymerization and grafting of methyl methacrylate (MMA) in the absence of any solvent. The modified CMK-3 carbon particles have a high loading of 19 wt% poly(methyl methacrylate) (PMMA), named PMMA-g-CMK-3, and also maintain their high surface area and mesoporous structure. The in situ polymerization technique endows a significantly enhanced electric conductivity (0.437 S m−1) of the resulting PMMA-g-CMK-3/PMMA composite, about two orders of magnitude higher than 1.34 × 10−3 S m−1 of PMMA/CMK-3 obtained by the solvent mixing method. A minimum reflection loss (RL) value of −27 dB and a broader absorption band (over 3 GHz) with RL values <−10 dB are obtained for the in situ polymerized PMMA-g-CMK-3/PMMA in a frequency range of 8.2–12.4 GHz (X-band), implying its great potential as a microwave absorbing material. The maximum absorbance efficiency for the in situ polymerized sample increases remarkably compared to that (−10 dB) of CMK-3/PMMA prepared by the solvent mixing method. Changing the thickness of the absorber can efficiently adjust the frequency corresponding to the best microwave absorbance ability. The enhanced microwave absorption by the surface modified CMK-3 is ascribed to high dielectric loss. This in situ polymerization for the surface modification of mesoporous carbons opens up a new method and idea for developing light-weight and high-performance microwave absorbing materials.

Hierarchical porous TiO2-carbon hybrid composites with a hollow structure were successfully fabricated by a one-pot low-temperature solvothermal approach in the presence of dodecylamine. The growth mechanism of the hierarchical hollow spheres was demonstrated to include the condensation of a carbon source and the co-instantaneous in situ hydrolysis of Ti-alkoxide, and the consequent assembly of TiO2@C hybrid nanoparticles on a self-conglobated template. As compared with the TiO2@C solid spheres (86%), the hierarchical TiO2@C hybrid hollow spheres exhibited an enhanced photocatalytic efficiency (97%) for the visible-light photooxidation of rhodamine B. Investigations demonstrated that the enhancement can be attributed to the hierarchical porous hollow structure. Moreover, the superoxide radical was detected as the main active species generated in the oxidation reaction of RhB over TiO2@C photocatalysts. A corresponding mechanism was also proposed for the photocatalysis process.

In order to investigate the effect of sintering schedule on the microstructure and the property, Dy-α-Sialon ceramics were sintered by hot pressing (HP) method via three intended schedules: (1) heated the sample to 1720 °C, then rapidly cooled down to room temperature (RT), (2) heated the sample to 1720 °C, then directly cooled down to 1650 °C and hold the temperature for 60 min before cooled down to RT, and (3) heated the sample to 1720 °C and hold there for 60 min then cooled down to RT. A series of positions on the as-sintered ceramic disc along the center to the edge were chosen to study their microstructure, optical transmittance and mechanical properties. The non-uniformity of microstructure and properties along the radial direction of the as-sintered samples was justified to be caused by the varied thermal schedules. This may develop methods to fabricate gradient ceramics.

At present stage, the transmittance improvement is still a thorny problem in SiAlON ceramics due to their complex composition and processing. In the present research, Dy–α-SiAlON ceramics were selected to be translucent in the medium infrared range. The samples had a higher densification value by using hot-pressing (HP) sintering method at 1650–1700 °C with or without LiF additive. The as-sintered specimens experienced the post-hot-isostatic-pressing (PHIP) treatment at 1650–1700 °C for 30–90 min in either N2 or Ar environment to increase the optical transmittance. A significant optical transparency improvement has been found in Dy–α-SiAlON, with or without LiF co-doping, undergone a PHIP at 1700 °C for 30 min under an Argon gas pressure of 180 MPa. The improved transmittance attributes to a fully developed α-Sialon crystalline phase, a uniform grain size, a denser grain arrangement, and a clean grain boundary, based on the X-ray diffraction analysis, SEM and TEM microstructure observation, and optical transmittance measurement.Highlights► Dense and translucent Dy–α-SiAlON ceramics. ► Post-hot-isostatic-pressing (PHIP) treatment in Ar environment. ► Significant optical transparency improvement.

Ordered bimodal mesoporous boria–alumina composite (OBMBAC) with high specific surface area and pore volume has been prepared through an evaporation-induced self-assembly (EISA) process using non-ionic block copolymer as a template without addition of any mineral acids such as HCl or H2SO4. Nitrogen adsorption test, low-angle X-ray diffraction (XRD) and high resolution TEM evidenced a novel bimodal mesoporous structure of the composite. The wide-angle XRD pattern showed that the composite was typical of poorly crystallized material. Solid MAS NMR and FT-IR analysis confirmed the chemical bonding of BOAl bonds in the composite. NH3-TPD (Temperature programmed desorption) test showed that the composite possessed complex acid sites. And strong Lewis and Brønsted acid sites can be detected. In the reaction of methanol dehydration to dimethyl ether (DME), the composite demonstrated high catalytic activity in conversion of methanol (85%) and good selectivity (100%) of DME. These characteristics of the ordered bimodal mesoporous boria–alumina composite are desirable for future applications related to effective utilization of DME as “green energy source” or aerosol propellant.Graphical abstractOrdered bimodal mesoporous boria–alumina composite with high specific surface area and pore volume has been prepared through an evaporation-induced self-assembly (EISA) process using non-ionic block copolymer as a template without addition of any mineral acids such as HCl or H2SO4.Highlights► One-pot synthesis of bimodal mesoporous boria–alumina composite without mineral acids. ► It possessed not only high surface area and pore volume, but also dual narrow pore size distributions. ► Strong Brønsted and Lewis acid sites in the composite. ► High activity for the dehydration of methanol.

A combinatorial chemistry method was employed to screen the yellow phosphors of (Lu1−xGdx)3Al5O12:Ce3y as luminescenet materials. An array of 81 compositions was synthesized by inkjetting nitrate solutions into microreactor wells and sintering at high temperature. The candidate formulations were evaluated by luminescence pictures, and the optimal composition was determined to be Lu2.7Gd0.3Al5O12:Ce0.045 after scale-up and detailed characterization. Lu2.7Gd0.3Al5O12:Ce0.045 was also found to have a short decay time (≤53.97 ns). These results demonstrate the great potential of the Lu2.7Gd0.3Al5O12:Ce0.045 as a component of ceramic scintillators.Keywords (keywords): (Lu1−xGdx)3Al5O12:Ce3y; combinatorial inkjetting solutions; luminescence

A combinatorial chemistry method was used to synthesize and screen (YxLu1−x−y)3Al5O12:Ce3y green-yellow phosphors. The material libraries were obtained using an inkjet delivery system and screened for their fluorescence under an ultraviolet light of 365 nm. The optimized composition was identified to be (Y0.2Lu0.788)3Al5O12:Ce3+0.036. Scale-up experiments confirmed that the optimized composition of the phosphor showed the highest luminescence intensity and an excellent scintillation performance with a short decay time (<60 ns). The results indicated that the (YxLu1−x−y)3Al5O12:Ce3y could be potentially useful as green-yellow phosphors for ceramic scintillators.

Work on the synthesis, characterization and structure change of the ordered mesoporous phosphates oxynitrides materials is described. Ordered mesoporous phosphates oxynitrides materials, characterized by high surface area, narrow pore-size distribution and good order, were synthesized through treating amorphous phosphates mesoporous molecular sieves at high temperatures in flowing ammonia. Adjusting the nitridation time and temperature can easily control the nitrogen contents of the oxynitride materials. The different amine groups are confirmed to exist on the mesopore surfaces of the obtained ordered mesoporous phosphates oxynitrides. At the same time, an apparent kinetics equation was built to fit the nitrogen content data of ordered mesoporous phosphates oxynitrides and the nitridation process accords with first-order reaction kinetics equation. 27Al and 31P MAS NMR and in situ FT-IR confirmed that nitrogen was incorporated into the phosphate framework. TEM, powder XRD and N2 sorption evidenced the good structural ordering of the mesoporous phosphate oxynitrides materials.

A combinatorial method was utilized to fabricate a Zn–Al material library by ion beam sputtering. The material library was produced by manipulating the position of substrate and moving shutters to deposit multilayer metal films. As-deposited films were annealed at low temperatures to form through-thickness homogenous films. Different annealing conditions were studied and high quality alloy films could be obtained by annealing at 370 °C. Electrochemical corrosion properties of the material library were evaluated by a modified tape test. Results of the electrochemical tests show that the Zn–Al film with a composition of 72.6 wt% Al has the best anti-corrosion properties in the material library. Nanoindentation tests were conducted to investigate the mechanical behaviour. Zn–Al films containing a high content of Al possess better mechanical properties with a high hardness and elastic module.

Compositional, textural and in vitro bioactive comparisons between surfactant-templated mesoporous (MCBS) and conventional sol–gel-derived CaO–B2O3–SiO2 (CBS) glasses are studied in this paper. CBS glasses are heterogeneous in composition. Due to the heterogeneity, melting boron oxide that formed during the heat treatment will fill in the pores that should have been generated by decomposition of calcium species. So, unlike other conventional sol–gel-derived bioactive glasses that have disordered and widely distributed mesopores, the CBS glasses are almost nonporous. MCBS glasses are more homogeneous in composition than CBS glasses, mainly ascribed to the effect of the surfactant. MCBS glasses of different compositions possess wormhole-like mesoporous structure and have similar pore size. In vitro bioactive tests show that wormhole-like MCBS glasses are more bioactive than CBS glasses, due to their high porosity.Surfactant-templated mesoporous CaO–B2O3–SiO2 glasses (MCBS) are superior to conventional sol–gel-derived CaO–B2O3–SiO2 glasses (CBS) in compositional homogeneity, textural properties and in vitro bioactivity.

Aluminum-incorporated SBA-15 materials with well-ordered structure, high surface area and narrow pore-size distribution were directly prepared by an evaporation-induced self-assembly (EISA) method. Our synthesis method with two unique points of no mineral acid and hydrothermal treatment, is very simple, efficient and energy-saving by using the corresponding chloride precursors which can generate proper acidity in the synthesis solutions. The mesopores ordering degree of Al-SBA-15 materials decreased when the Al/Si atomic ratio was either larger than 0.08 or smaller than 0.05. The powder X-ray diffraction (XRD), N2 sorption and transmission electron microscopy (TEM) characterizations show that the resultant materials have well ordered hexagonal mesostructures. The 27Al magic angle spinning (MAS) NMR characterizations show that most of the aluminum ions incorporate into the SBA-15 framework. The thermal analysis was used to probe the interaction between the silica species and copolymer templates.

A simple and direct-synthesis route without mineral acids added was successfully developed to prepare Sn or Al-containing SBA-15 mesoporous materials with good mesostructural ordering, high surface area and narrow pore-size distribution via evaporation-induced self-assembly (EISA) process in which no mineral acids were added and no hydrothermal treatment was needed. Compared with other direct-synthesis methods of metal ions substituted SBA-15 materials reported early, our synthesis method, with two unique points of no mineral acid and hydrothermal treatment route, is very simple, efficient and energy-saving. These materials were characterized by powder X-ray diffraction (XRD), N2 sorption isotherms, TEM with EDS analysis, 27Al MAS NMR, and UV–visible absorption spectra.

Mesoporous borosilica oxynitrides were prepared by heat treatment of boron substituted MCM-41 in flowing ammonia at high-temperatures. Based on absorption–desorption isotherms, high-resolution transmission electron microscopy (HRTEM) and small-angle X-ray diffraction (SAXRD) measurement of the samples, it was found that the mesostructured ordering, high BET surface area and narrow pore size distribution of B-MCM-41 could be maintained after nitridation. Mesostructured borosilica oxynitrides may be potential acid–base solid catalysts in future.

We successfully synthesized the large-scale and uniform rare earth (Eu or Tb) doped lutetium compounds with square nanosheets using the doped Lu(OH)3 colloidal precursors by the hydrothermal method without any catalysts or templates at 140 °C and pH 13–14 for 24 h. The as-synthesized nanosheets have square shape morphology with the side lengths of 200–400 nm and thickness of ∼40 nm. We deduced a mechanism of “side wrapping” to describe the growth of the square nanosheets. The doped Lu2O3 phosphors with square nanosheets have been synthesized by a thermal decomposition method at 900 °C for 2 h using doped lutetium compounds as precursors.

Wormhole-like mesostructured alkali-free borosilicate glasses (MBSGs) with different compositions have been synthesized by a combination of surfactant templating, sol–gel methods and evaporation-induced self-assembly (EISA) processes.

Highly-ordered, pore-modified with amine groups, and glasslike mesoporous silicon oxynitride thin films were prepared by heat treatment of as-synthesized mesoporous silica thin films in a flowing ammonia environment at high temperatures.

In this contribution, we report the successful preparation of large-scale and uniform europium-doped lutetium compounds with the varied morphologies of nanoflakes, nanoquadrels and nanorods, using colloidal Lu(OH)3–Eu at different concentrations as a precursor for the hydrothermal method (170 °C and pH = 13 for 24 h). The as-made products have different crystalline structures as well as different morphologies. The as-synthesized nanoflakes have a “perfect” square shape with side lengths of 220–400 nm and thicknesses of 50 nm or below. On the basis of the observed “non-perfect” nanoflakes, we have deduced a mechanism of “side wrapping” to describe the growth of the “perfect” square nanoflakes. The as-made nanoquadrels possess a sandwich-like nanostructure and they are all composed of several square nanoflakes via face-to-face “self-reorganization”. The formation of nanorods is due to the high chemical potential resulting from the high precursor concentration. At the same time, the pH value of the precursor and the method of mixing of the lanthanide nitrate solution with the NaOH solution have a great effect on the morphology of the as-synthesized products. The shapes of the as-made products were sustained after thermal decomposition to europium-doped Lu2O3. The crystalline structure, morphology and thermal behavior of as-synthesized products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TG) and differential scanning calorimetric analysis (DSC), respectively.

Work on the characterization and structural change of nitrogen-containing SBA15 materials under heat treatment is described in this paper. The SBA15 oxynitride materials, characterized by high surface area, big mesopores (above 6 nm) and good order, were synthesized through treating pure silica SBA15 mesoporous molecular sieves at high temperatures with ammonia. The temperature controlled the nitrogen content of the oxynitride materials. 29Si MAS NMR and FTIR confirmed that nitrogen was incorporated into the SBA15 framework. HRTEM, powder XRD and N2 sorption evidenced the good structural ordering of the nitrided SBA15 materials. It was found that the oxynitride materials went through a mesopore structural change under heating in both inert atmosphere and air when the treatment temperature was 600 °C or less. This kind of mesoporous oxynitride sieve with big mesopores and excellent thermal stability could be used as a kind of solid base catalyst especially for the large molecule interaction.

Ultrafine Ba0.5Sr0.5TiO3 powders were prepared by using barium nitrate, strontium nitrate, tetrabutyl titanate, and ammonia via citrate–nitrate combustion process at low temperature (500 °C), along with the X-ray diffraction (XRD), differential scanning calorimetry (DSC)/thermogravimetry analysis (TGA) and scanning electron microscopy (SEM) analytic reports. Spark plasma sintering was carried out to obtain the ultrafine crystalline BST and to improve the dielectric properity. It was found that the sintered BST showed ultrafine crystalline microstructure. At 25 °C, the dielectric constant and dissipation factor of the sintered sample were 1533 and 0.0063 at 10 kHz.

Er3+-doped Ba0.5Sr0.5TiO3 (BST) powders were prepared by using barium nitrate, strontium nitrate, tetrabutyl titanate, and ammonia via citrate–nitrate combustion process, along with the XRD, DSC/TGA, and SEM analytic reports. The Er3+ luminescence intensity reached a maximum value in the sample with 3 mol% Er3+ ions concentration sintered at temperature 1300 °C. We also showed that 1 mol% Er dopant improved the dielectric property of BST and the BST:Er materials may have potential use for electroluminescence devices.

The commercial ZSM-5 zeolites (Si/Al=50 and 19 respectively) were treated for n hours at determinate temperatures. After the heat treatment under different conditions, a new kind of ZSM-5 with bimodal pore was developed, in which the part of original microporous structure in ZSM-5 was remained, but some of mesopores with narrow pore size distribution were formed in the same matrix. The experiments showed that the characteristics of the composite molecular sieves with mesopores and micropores strongly depended on the heat treatment conditions. To evaluate the new molecular sieves, microstructure and physical properties of the treated ZSM-5 were investigated by N2 sorption, XRD, SEM and HRTEM. The process developed in the present work provides a convenient method to prepare bimodal porous material with advantages of low cost, easy control and good repeatability.

The thermal stability of Si–MCM-41 in different atmosphere (air, O2, NH3, N2, and Ar) has been investigated in the present work; as-synthesized Si–MCM-41 was heat-treated at 800–1030 °C for 6–12 h in the selected atmosphere. Based on absorption–desorption isotherms and low-angle XRD measurement of the treated samples, it was found that the thermal stability varied greatly in different atmosphere. As-synthesized Si–MCM-41 retained mesoporous structure up to 1010 °C in NH3, N2, and Ar environment, but in air and O2 environment, the highest thermal stable temperature of mesoporous structure in Si–MCM-41 was no more than 900 °C.

The high-activity electrocatalysts for the hydrogen evolution reaction (HER) are highly desired to replace precious Pt, but difficult to achieve. Herein, we report the loading of ultrafine tungsten carbide (WC) nanoparticles (NPs) on cobalt-embedded, bamboo-like, nitrogen-doped carbon nanotubes (WC/Co@NCNTs) with high-level N doping via a one-step strategy, leading to a desirable multicomponent nanocomposite with superior activity and stability when used as the HER electrocatalyst. The optimized WC/Co@NCNTs showed a very low onset overpotential (Uonset) of ~18 mV, a small Tafel slope of 52 mV dec−1, a small η10 of only 98 mV to reach a current of 10 mA cm−2, and a large exchange current density (j0) of 0.103 mA cm−2, which also retained its high activity for at least 12.5 h operation in acidic electrolyte. The DFT calculations revealed an important role of the N dopants in the HER as well as a favorable ΔGH* for the adsorption and desorption of hydrogen derived from the synergistic effects between WC NPs and Co@NCNTs.A multicomponent nanocomposite of ultrafine WC nanoparticles anchored on Co-encased, N-doped carbon nanotubes prepared by one-step pyrolysis of low-cost precursors can serve as hydrogen-generating electrocatalyst with excellent activity and superior stability in acidic electrolyte.Download high-res image (191KB)Download full-size image

Nitrogen-doped hollow mesoporous carbon spheres (NHCSs) were successfully prepared via a simple, scalable hydrothermal method, followed by thermal treatment at 650 °C in ammonia atmosphere and subsequent high temperature annealing at 800–1000 °C in nitrogen, respectively. The resulting NHCSs with a particle diameter of ∼150 nm and a shell thickness of ∼20–25 nm have high specific surface areas (738–820 m2 g−1), large pore volume (0.50–0.56 cm3 g−1), bimodal pores system (3.9 and 51.6 nm) and adjustable N-doping levels (3.6–7.8 at.%) depending on the pyrolysis temperature. The unique structure of hollow spheres for NHCSs with uniform mesopores throughout the shells can both promote fast mass transfer and provide inner and outer surfaces with high density of N-related active sites, thus improving the reaction kinetics. The NHCS-1000 (annealed at 1000 °C) exhibited not only comparable ORR activity with a direct four-electron reaction pathway in terms of onset and half-wave potentials, and limiting current densities, but superior long-term durability and methanol-tolerance to commercial Pt/C catalyst, because it has the highest relative content of graphitic-N and pyridinic-N groups, indicating their crucial roles in ORR. The NHCS-1000 with excellent ORR performance is of potential to replace Pt/C catalyst for ORR in practical applications.

Polyacrylonitrile (PAN)-based carbon nanofibers prepared by electrospinning were physically activated using carbon dioxide as the oxidizing agent. The activation procedure was performed at 800 °C for different periods of time ranging from 15 to 60 min. The activated materials have a hierarchical structure with two sets of pore systems in the micropore range centered at ∼0.8 nm and small mesopore range centered at ∼2.8 nm. The activation not only increased the specific surface area and pore volume to 1123 m2 g−1 and 0.64 cm3 g−1, respectively, but also resulted in the evident loss of doped N atoms. The pyridinic and graphitic nitrogen groups are dominant among various N functional groups in the activated samples. CACNF-60, prepared by activating the carbon nanofibers (CNFs) for 60 min, showed excellent electrocatalytic activity for the oxygen reduction reaction (ORR) as well as superior long-term stability and methanol tolerance compared to commercial Pt/C in alkaline media. The excellent electrocatalytic activity of the activated sample is mainly due to its high N content (6.9 at%), unique hierarchical micro-/mesoporosity, and large specific surface area.

A new Eu2+ activated, G-type La2Si2O7 phosphor was synthesized successfully via a novel SiC-reduction route. The valence state of the Eu2+ ions was identified with XRD and XPS analysis and the luminescence spectrum presented Eu2+ broad bands. The G-La2Si2O7:Eu2+ (LPS:Eu2+) phosphor exhibited tunable emission colors depending on the excitation wavelength or the Eu concentration, enabling the production of white light. The color tunable property is ascribed to the component ratio of the two specific luminescent centers, Eu(1) and Eu(2). Eu2+ ions prefer to occupy the La3+ crystallographic sites selectively, which was identified by electron paramagnetic resonance (EPR) spectroscopy. Furthermore, the relative emission intensity of the phosphor at 100 °C and 160 °C can maintain 89% and 76% of the value measured at room temperature, which is much better than that of most of Eu2+ doped silicon oxides phosphors. The Eu(1) emission possesses a better fluorescence thermal stability than the Eu(2) emission, and an energy transition from Eu(1) to Eu(2) occurs. This better thermal stability and energy transition have been explained by the schematic configuration coordination. A w-LED device was fabricated by combining the prepared La2Si2O7:Eu2+ and commercial BaMgAl10O17:Eu2+ phosphors with a 365 nm n-UV chip. The w-LED device generates white light (color rendering index Ra = 93.9), and its CIE chromaticity coordinates and correlated color temperature (CCT) are (x, y) = (0.3429, 0.3523) and 5090 K, respectively. These results suggest that LPS:Eu2+ has a great potential for use in UV-LED-driven white emitting diodes.

Gd2Si2O7:Ce (GPS:Ce) and (Gd,La)2Si2O7:Ce (La-GPS:Ce) phosphors with different crystal structures, tetragonal, orthorhombic and triclinic, were synthesized via a sol–gel technique. The prepared samples have been systematically investigated using room temperature (RT) XRD, high temperature (HT) XRD, HRTEM, selected area electron diffraction (SAED) and EDS elemental analysis. The results show that the phase transition occurred at 1350–1450 °C and the tetragonal phase was a low-temperature metastable phase and the orthorhombic and triclinic structures were stable at high temperatures. It was observed that the three structures display completely different luminescence efficiencies under both UV lamp and X-ray excitation, but the decay time was not strongly dependent on the crystal structure. The luminescence thermo-stability and activation energy were also measured and calculated. The results indicate that the thermo-stability was strongly dependent on the crystal structure and the GPS:Ce-1500 °C sample showed the best thermo-stability. The three materials have potential application as a novel type of scintillator.

The Y2Si4N6C:Ce3+ carbidonitride phosphor has been successfully synthesized via a novel acid-driven carbonization and carbothermal reduction nitridation method (ADC–CRN). This novel approach for Y2Si4N6C:Ce3+ promises lower heating temperature and shorter heating time than classical methods, indicative of a cost-effective and facile way to search for new silicon-based carbidonitrides. In contrast to Ce3+ activated (oxy)nitrides showing blue-green emissions, Y2Si4N6C:Ce3+ exhibits an individual green-yellowish emission band centered at 550 nm which is ascribed to the incorporation of highly covalent C4− into the host lattice. The sp3 hybrid C4− was identified through high resolution electron energy loss spectroscopy analysis (EELS). Direct evidence for sole substitution of Ce3+ for Y3+ in Y2Si4N6C is represented for the first time using electron paramagnetic resonance (EPR) spectra. The red shift induced by the increasing Ce3+ content in Y2Si4N6C is reasonably deduced by the energy transfer model of intra-Ce3+ and inter-Ce3+ ions. A pc-w-LED packaging was fabricated via a combination of the yellow Y2Si4N6C:Ce3+ and blue La2Si4N6C:Ce3+ phosphors prepared using a 365 nm n-UV chip. The w-LED device shows a good color rendering index (Ra), CIE chromaticity coordinates and correlated color temperature (CCT) of 83.8, (0.3258, 0.3314) and 5819 K, respectively. These results suggest that Y2Si4N6C:Ce3+ has great potential for use in UV-LED-driven white emitting diodes.

Hierarchical porous TiO2-carbon hybrid composites with a hollow structure were successfully fabricated by a one-pot low-temperature solvothermal approach in the presence of dodecylamine. The growth mechanism of the hierarchical hollow spheres was demonstrated to include the condensation of a carbon source and the co-instantaneous in situ hydrolysis of Ti-alkoxide, and the consequent assembly of TiO2@C hybrid nanoparticles on a self-conglobated template. As compared with the TiO2@C solid spheres (86%), the hierarchical TiO2@C hybrid hollow spheres exhibited an enhanced photocatalytic efficiency (97%) for the visible-light photooxidation of rhodamine B. Investigations demonstrated that the enhancement can be attributed to the hierarchical porous hollow structure. Moreover, the superoxide radical was detected as the main active species generated in the oxidation reaction of RhB over TiO2@C photocatalysts. A corresponding mechanism was also proposed for the photocatalysis process.

A series of novel nitrogen-doped hierarchical carbon monoliths (NCMs) with macroporous scaffolds composed of interconnected mesoporous rods were prepared successfully by a facile nanocasting strategy in combination with pyrolysis in a NH3 atmosphere. After etching off the hard template, the resulting NCMs had large macroporosity (up to 37.4 mL g−1) as well as large specific surface areas (1100–1600 m2 g−1), mesopore volumes (1.4–1.9 mL g−1), and narrow mesopore size distributions (3.8 nm). The nitrogen contents of the NCMs decreased from 4.7 to 1.6 at% with increasing pyrolysis temperature from 650 to 1050 °C. The pyridinic and graphitic nitrogen groups are dominant among various nitrogen-containing groups in the NCMs. Combined with their relatively high nitrogen-doping and unique hierarchical porous textures, NCM-750 exhibited comparable catalytic activity but superior long-term durability and methanol tolerance to commercial Pt/C for oxygen reduction reaction (ORR) with a four-electron transfer pathway in alkaline media. These excellent properties in combination with good recyclability and stability make these NCMs among the most promising electrocatalysts reported so far for efficient ORR in practical applications.

The lack of efficient electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) has been a fatal issue for the development of metal–air batteries in large-scale commercialization. In this paper, spinel CoFe2O4 (CFO) nanoparticles were successfully in situ grown onto rod-like ordered mesoporous carbon (RC) by a facile, scalable hydrothermal method, followed by annealing at different temperatures. The as-acquired CFO/RC nanohybrid pyrolyzed at 400 °C (CFO/RC-400) has a high specific surface area (150.3 m2 g−1) and two sets of uniform mesopore systems (3.38 and 19.1 nm), all of which are favorable for the improvement of the electrocatalytic activity. The hybridization of CFO nanoparticles and the RC matrix results in increased ORR and OER electrocatalytic activity of the CFO/RC nanohybrids, which is significantly superior to that of unsupported CFO nanoparticles and pure RC. CFO/RC-400 shows better catalytic activity for the ORR with a direct four-electron reaction pathway than those prepared at other temperatures in terms of the onset potential and limiting current density. Furthermore, the CFO/RC-400 nanohybrid exhibits outstanding durability for both the ORR and OER, and can outperform commercial Pt/C. The excellent bifunctional electrocatalytic activities of the CFO/RC nanohybrids are mainly owing to the hierarchical mesoporous structures of the nanohybrids and strong coupling between the CFO nanoparticles and the RC matrix.

The development of efficient non-precious-metal electrocatalysts towards the hydrogen evolution reaction (HER), with superior activity and stability, remains a great challenge in the area of renewable energy. In this work, we demonstrated a facile, one-step protocol to synthesize ultrathin graphitic layer (GL)-encapsulated ultrafine ditungsten carbide (W2C) nanoparticles (W2C@GL) with sizes smaller than 10 nm, exhibiting a superior HER activity in acidic solution. An efficient W2C phase, along with an improved electron transfer process by GL wrapping, cooperatively leads to a small Tafel slope of 68 mV dec−1 and a large exchange current density of 0.24 mA cm−2 for W2C@GL, which exceeds the previous W2C materials by far. Over 91% of the current density is maintained after over 8 h of operation, which indicates a good stability of this hybrid catalyst. Thus, W2C@GL with these excellent properties has been among the best non-noble metal HER electrocatalyst reported to date.

A series of magnetic γ-Fe2O3, Fe3O4, and Fe nanoparticles have been successfully introduced into the mesochannels of ordered mesoporous carbons by the combination of the impregnation of iron salt precursors and then in situ hydrolysis, pyrolysis and reduction processes. The magnetic nanoparticles are uniformly dispersed and confined within the mesopores of mesoporous carbons. Although the as-prepared magnetic mesoporous carbon composites have high contents of magnetic components, they still possess very high specific surface areas and pore volumes. The magnetic hysteresis loops measurements indicate that the magnetic constituents are poorly-crystalline nanoparticles and their saturation magnetization is evidently smaller than bulky magnetic materials. The confinement of magnetic nanoparticles within the mesopores of mesoporous carbons results in the decrease of the complex permittivity and the increase of the complex permeability of the magnetic nanocomposites. The maximum reflection loss (RL) values of −32 dB at 11.3 GHz and a broad absorption band (over 2 GHz) with RL values <−10 dB are obtained for 10-Fe3O4–CMK-3 and 10-γ-Fe2O3–CMK-3 composites in a frequency range of 8.2–12.4 GHz (X-band), showing their great potentials in microwave absorption. This research opens a new method and idea for developing novel magnetic mesoporous carbon composites as high-performance microwave absorbing materials.