AbstractTiO2 is a promising photocatalytic material for hydrogen generation. However, the fast recombination of electron–holes restricts the photocatalytic performance of TiO2. Herein, this study demonstrates a 2D-layered carbon/TiO2 (C/TiO2) architecture via CO2 oxidation of 2D-Ti3C2, in which the 2D carbon layers provide electron transport channels and improve the hole–electron separation efficiency. Compared to Ti3C2 support, the thickness of derived carbon supports is significantly reduced, which enhances the light intensity arriving at the surface of TiO2. The oxidation parameters are investigated systematically. It is found that high temperature and high CO2 gas flux lead to the formation of crystal TiO2 and the oxidation of carbon layers. The bandgap of 2D-layered C/TiO2 samples is ranged from 2.83 to 2.89 eV. The 2D-layered C/TiO2 delivers enhanced photocatalytic activity compared with pure TiO2 catalysts. The optimal photocatalytic hydrogen evolution rate of 2D-layered C/TiO2 is up to 24.04 µmol h−1, which is about 89 times higher than that of pure TiO2. This research broadens the applications of C/TiO2 hybrids and provides new approach to synthesize novel 2D-layered materials for photocatalytic applications.

•A kind of molybdenum oxide nanostructures can be synthesized via facile synthetic approaches.;•The prepared rod-like MoOx displays well crystalline nature and take place phase conversion from MoO3 to MoO2.;•The obtained MoO2 as catalyst exhibits high catalytic activity and cycling durability in HER.In this report, molybdenum oxide (MoOx) nanomaterials are synthesized simply by a two-step thermal treatment of the prepared Mo3O10/ethylenediamine (EDA) complex precursor. The prepared MoOx nanostructures are highly crystalline and have plate- and rod-like morphologies. With increasing of the reduction temperatures, the prepared molybdenum oxide undergoes a phase conversion from MoO3 to MoO3/MoO2 and finally to MoO2. The prepared MoO2 materials are used as electrocatalysts in the hydrogen evolution reaction (HER), they can display high catalytic activity (∼79.35 mA/cm2), low Tafel slopes (∼87.1 mV/dec), and excellent cycling durability. It is believed that the excellent electrocatalytic performances are resulted from the high conductivity and large number of active sites on the surface of MoO2. Importantly, the facile, scalable, energy-efficient and environmentally friendly nature of the presented approach renders it particularly attractive for technology applications.

In this study, a type of porous carbon-coated SnO2 nanoparticle composite (SnO2@PC) was produced in the presence of a silica template. The prepared SnO2@PC composite displays a highly specific surface area (SSA) and large pore volume compared with common porous carbons. Electrochemical testing demonstrates that as an anode material the SnO2@PC1 composite can deliver a specific capacity of 1130.1 m Ah g−1 at a current density of 0.2 A g−1 after 100 cycles, which is much higher than that of pure SnO2 anodes. The specific capacity of the SnO2@PC1 anode is as high as 770.3 m Ah g−1 at a current density of 0.5 A g−1 after 300 cycles, indicating excellent rate and cycling capability. The superior lithium storage performance of the SnO2@PC1 composite can be attributed to the synergistic effect of the porous carbon and SnO2 nanoparticles. In addition, the large specific surface area and pore volume of the SnO2@PC1 composite can significantly shorten the diffusion path of lithium ions and provide a sufficient internal void space for volume change. The proposed synthetic approach is facile, controllable, and economical, and can be applied in producing carbon coatings for other transition metal oxide-based composite functional materials.

⿢Dumbbell-like Co3O4 was obtained via calcination of the spindle-like CoCO3 precursor.⿢The Co3O4 anode exhibit high capacity and excellent cycling durability.⿢The excellent storage lithium of the Co3O4 can be ascribed to the porous features and selective crystal facets effects.In this study, dumbbell-like Co3O4 is obtained via calcination of the prepared spindle-like CoCO3 precursor. The Co3O4 displays high specific surface area of 162.7 m2 g⿿1 and narrow pore-size-distribution of 3.54 nm. When applied as anode material, Co3O4 delivers a specific capacity as high as 1719 mA h/g for initial discharge, and retains low discharge capacity loss over 200 cycles at 0.1C conditions. The improved lithium storage capability of the Co3O4 anode can be attributed to high specific surface area and the shortened transport path for Li+ that resulted from specific facet effects.

Multi-yolk–shell Bi@C nanostructures were prepared via a facile one-pot template-free hydrothermal approach. The prepared Bi@C nanostructures can act as a solid catalyst in the thermal decomposition of cyclotrimethylenetrinitramine (RDX) and display excellent catalytic activity, which highlights their application in the field of energetic materials.

•Specific porous silver monoliths were prepared via thermal-reduction process.•The porous Ag monoliths display enhanced catalytic activity and durability over reduction of P-nitrophenol.•The present synthetic approach is facile, environmentally benign, and amenable to scale-up process.In this study, novel porous silver (Ag) monoliths have been successfully prepared via a facile process by combining an aging treatment with a thermal-induced reduction reaction. The obtained Ag samples display distinct morphologies via simply adjusting reaction conditions such as aging temperature and precursor’s concentrations. More interestingly, the as-made porous Ag samples exhibit superior catalytic activity and durability in the catalysis over reduction of P-nitrophenol (4-NP). Remarkably, the synergistic effects of stabilizing and oxidative etching agents should be responsible for the fabrication of hierarchical metallic monoliths, which highlight significant advantages over the existing techniques given that the present method is facile, inexpensive, environmentally benign, and amenable to scale-up process.A kind of novel porous Ag monoliths (include spherical and hierarchical) was prepared via direct aging reaction followed by a facile thermal-induced reduction process. The as-made porous Ag monoliths exhibit superior activity and durability in the catalysis over reduction of P-nitrophenol (4-NP).

In this study, a kind of unique Fe2O3/Pt hybrid consisting of uniform platinum nanoparticles deposited on a nanoflake-shaped Fe2O3 support was prepared by using a solvothermal reaction followed by a heat-induced reduction process. The prepared Fe2O3 sample displays well-defined nanoflake-like morphology; remarkably, there are many specific cavities on its surface. In addition, uniform Pt nanoparticles with narrow size distribution were deposited onto the surface of the preformed flake-like Fe2O3 support to form the Fe2O3/Pt hybrid via a facile heat-induced reduction reaction. Thus, the prepared Fe2O3/Pt hybrid can serve as heterogeneous catalyst over the hydrogenation reaction. Results demonstrated that the specific Fe2O3/Pt heterogeneous catalyst exhibits good catalytic performances, including high conversion, specific selectivity, and excellent recycling durability, over hydrogenation reactions for different substrates. Furthermore, the prepared Fe2O3/Pt heterogeneous catalyst could be easily separated from the product mixture by using a magnet and could be recycled for 10 cycles without catalytic activity loss. In a word, the present synthetic approach is facile, scalable, and reproducible, which can be easily facilitated to prepare other types of noble metals/metal oxide composite systems.Keywords: flake-like; heterogeneous catalyst; hydrogenation; iron oxide; Pt nanoparticle;

In this work, porous Co3O4 materials were prepared via a solid-state conversion process of a freshly prepared cobalt-based metal–organic framework (Co-MOF) crystal. Herein, the unique Co-MOF crystal was formed via the specific chemical coordination between the carboxylic ligand azobenzene-3,5,4′-tricarboxylic acid (H3ABTC) and the auxiliary ligand 4,4′-bipyridine (bpy) to construct 2-dimensional (2D) bilayer structural intermediates, which subsequently formed a 3D polycatenation supramolecular array architecture with the assistance of π–π stacking and hydrogen bonding interactions. Subsequently, porous Co3O4 particles were obtained by simple thermolysis of the Co-MOF crystals via a two-step calcination treatment. The results demonstrated that the as-made Co3O4 displays crystalline and well-defined porous features and can be applied as a supercapacitor electrode, and its energy storage performances were investigated in 2 M KOH electrolyte. The electrochemical results showed that the porous Co3O4 particles exhibit a high specific capacitance of 150 F g−1 at a current density of 1 A g−1 and retain slightly enhanced capacitance after 3400 cycles, which could be ascribed to its higher specific surface area and accessible channel structural features. The present approach is facile, controllable, and reproducible. Importantly, this specific solid-state thermal conversion strategy could be easily extended to prepare other porous metal and/or metal oxide nanomaterials with specific surface textures and morphologies.

In this report, a class of homogeneous core/shell Bi2WO6 spheres was successfully synthesized via mild solvothermal reaction processes in the presence of Polyvinylpyrrolidone (PVP). Moreover, the as-prepared core/shell structure can combine with noble metals such as Au and/or Pt via light-reduction process to form their composite spheres. The obtained Bi2WO6-based samples were characterized by X-ray powder diffraction (XRD), scan electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), and UV-visible diffuse reflectance techniques. Results demonstrated that the as-prepared Bi2WO6 samples exhibit good crystalline feature. The specific core/shell Bi2WO6-based samples could be employed as visible-light-responsive catalyst towards to decomposition of Rhodamine B (RhB) under visible-light irradiation, their photocatalytic efficiency displays significantly enhancement compared with their P25, SSR-Bi2WO6, and/or previously prepared Bi2WO6, which could be attributed to their higher specific surface, unique core/shell structure, and retardation of the recombination of photo-generated holes and electrons. More importantly, the present synthetic approach can be facilitated to prepare novel composite catalysts with specific morphologies and architectures.

Various kinds of nearly spherical calcium carbonate (CaCO3) crystals with hierarchical and porous structures can be prepared using poly(ethylene glycol)-b-poly(aspartic acid) (PEG-b-pAsp) as a crystal growth modifier in a mixed solvent composed of N,N-dimethylformamide (DMF) and cyclohexanol. The results reveal that the porosity or specific surface area of these CaCO3 crystals can be tuned by altering the volume ratio (R) of DMF/cyclohexanol in solution, and the pore size of the obtained spherical particles can be ranged from several tens to hundreds of nanometres. Additionally, most of the obtained calcium carbonate samples can be assigned to vaterite or a mixture of calcite and vaterite, which are well crystalline and are influenced by the R value. Interestingly, unique hierarchical and porous microspheres can be prepared at polymer concentrations of ∼ 0.5 g L−1 and an R value of ∼ 1.0, respectively. It has been proposed that the formation of the specific CaCO3 crystals with hierarchical and porous structures could be ascribed to the collodial aggregation transition and self-assembly of calcium carbonate precursor in a desirable mixed solvent. This specific synthesis strategy in a mixed solvent again emphasizes that it is possible to synthesize other inorganic/organic hybrid materials with exquisite morphology and specific textures.

In this paper, we report that hydroxyapatite (HAP) nanocrystals with various shape and size have been successfully prepared by a dual template-assisted hydrothermal synthesis approach in isopropanol/water mixed solvents. Herein, we chose 4-aminobenzenesulfonic acid (ABSA) and polyethylene glycol 4000 (PEG-4000) as structure-directed templates, respectively. By gradually changing the mass ratios (R) of PEG-4000 to ABSA, the obtained HAP samples can undergo distinct morphological evolution accordingly. A class of unique sheet-like HAP sample could be formed when only using ABSA as template. Moreover, when the R value was changed to 1/4, uniform and high-yielding HAP plate-shaped structure can be obtained. When only using PEG-4000 as a template, almost novel and wedge-shaped HAP samples can be obtained. The results demonstrated that the obtained plate-like HAP sample has single-crystalline behavior and uniform distribution in both size and shape. Additionally, we perform and evaluate the bioactivity of HAP in simulated body fluid (SBF), indicating that the two obtained HAP samples can possess apparently improved bioactivity compared to previous literature reports, and bone-like apatite could be readily formed on the HAP surface through different soaking periods in SBF. Notably, for the first time, a novel method for evaluating the in vitro bioactivity of HAP has been proposed. Therefore, the presented synthetic route for HAP is well-controlled and facilitated, which could be extended to the preparation of other biomaterials with specific morphologies and architectures.

Facile production of high quality activated carbons from biomass materials has greatly triggered much attention presently. In this paper, a series of interconnected porous carbon materials from lotus root shells biomass are prepared via simple pyrolysis and followed by a KOH activation process. The prepared carbons exhibit high specific surface areas of up to 2961 m2/g and large pore volume ∼1.47 cm3/g. In addition, the resultant porous carbons served as electrode materials in supercapacitor exhibit high specific capacitance and outstanding recycling stability and high energy density. In particular, their specific capacitance retention was almost 100% after 10500 cycles at a current density of 2 A/g. Remarkabely, the impact of the tailored specific surface areas of various carbon samples on their capacitive performances is systematically investigated. Generally, it was believed that the highly-developed porosity features (including surface areas and pore volume and pore size-distributions), together with the good conductivity of activated carbon species, play a key role in effectively improving the storage energy performances of the porous carbon electrode materials in supercapacitor.Porous carbons were prepared by simple pyrolysis and followed by KOH activation of Lotus root shell. The prepared carbon based electrodes exhibit ultra-high specific surface areas and outstanding recycling stability.Download high-res image (216KB)Download full-size image

In this work, porous Co3O4 materials were prepared via a solid-state conversion process of a freshly prepared cobalt-based metal–organic framework (Co-MOF) crystal. Herein, the unique Co-MOF crystal was formed via the specific chemical coordination between the carboxylic ligand azobenzene-3,5,4′-tricarboxylic acid (H3ABTC) and the auxiliary ligand 4,4′-bipyridine (bpy) to construct 2-dimensional (2D) bilayer structural intermediates, which subsequently formed a 3D polycatenation supramolecular array architecture with the assistance of π–π stacking and hydrogen bonding interactions. Subsequently, porous Co3O4 particles were obtained by simple thermolysis of the Co-MOF crystals via a two-step calcination treatment. The results demonstrated that the as-made Co3O4 displays crystalline and well-defined porous features and can be applied as a supercapacitor electrode, and its energy storage performances were investigated in 2 M KOH electrolyte. The electrochemical results showed that the porous Co3O4 particles exhibit a high specific capacitance of 150 F g−1 at a current density of 1 A g−1 and retain slightly enhanced capacitance after 3400 cycles, which could be ascribed to its higher specific surface area and accessible channel structural features. The present approach is facile, controllable, and reproducible. Importantly, this specific solid-state thermal conversion strategy could be easily extended to prepare other porous metal and/or metal oxide nanomaterials with specific surface textures and morphologies.

Multi-yolk–shell Bi@C nanostructures were prepared via a facile one-pot template-free hydrothermal approach. The prepared Bi@C nanostructures can act as a solid catalyst in the thermal decomposition of cyclotrimethylenetrinitramine (RDX) and display excellent catalytic activity, which highlights their application in the field of energetic materials.