In this work we present the synthesis of a new type of nitrogen-doped tantalate, Sr2Ta2O7-x N x , which exhibited significantly increased visible light absorption and improved photocatalytic hydrogen ...production by 87% under solar irradiation, compared with its undoped counterpart Sr2Ta2O7. The photocatalyst also exhibited a strong capability in photoinduced reduction of exfoliated graphene oxide (GO) to graphene sheets. By using graphene as a support for a Pt cocatalyst, a new type of composite containing graphene-Pt and Sr2Ta2O7-xN x was designed, which demonstrated an additional ∼80% increase in hydrogen production and an quantum efficiency of 6.45% (∼177% increase from pristine undoped Sr2Ta2O7) due to the efficient charge carrier separation on the photocatalyst. This work suggests that graphene can play an important role as an electron transfer highway, which facilitates the charge carrier collection onto Pt cocatalysts. The method can thus be considered as an excellent strategy to increase photocatalytic hydrogen production in addition to a commonly applied doping method.
Owing to the weak self-assembly ability of precursor components and the serious crosslinking of neighbouring nanospheres during a hydrothermal process, the synthesis of monodisperse mesoporous ...polymer nanospheres with diameters below 500 nm remains a great challenge. Here we extend the synthesis method of mesoporous silica nanospheres to enable the preparation of ordered mesoporous resorcinol formaldehyde nanospheres with particle size from 80 to 400 nm and mesopores of ~3.5 nm in diameter. By finely tuning the synthesis parameters, multi-layered mesoporous resorcinol formaldehyde hollow nanospheres can be successfully synthesized. Mesoporous carbon nanospheres and hollow nanospheres with high surface area are further obtained through carbonization of the polymer spheres. The resulting mesoporous carbon nanospheres are demonstrated as the host cathode material for lithium-sulphur batteries. The synthesis strategy provides a benchmark for fabricating well-defined porous carbonaceous nanospheres with potential for energy storage and conversion applications.
Yolk/shell or 'rattle-typed' nanomaterials with nanoparticle cores inside hollow shells are interesting among the complex hollow nanostructures. Yolk/shell nanoparticles (YSNs) are promising ...functional nanomaterials for a variety of applications such as catalysis, delivery, lithium-ion batteries and biosensors due to their tailorability and functionality in both the cores and hollow shells. This feature article provides an overview of advances in this exciting area of YSNs, covering systematic synthesis approaches and key promising applications based on the literature and our own recent work. We present some strategies for the synthesis of YSNs with controllable sizes, compositions, geometries, structures and functionalities. Applications of these new materials in a wide range of potential areas are discussed including nanoreactors, biomedicine and lithium-ion batteries. Promising future directions of this active research field are also highlighted.
Electronic structure intrinsically controls the light absorbance, redox potential, charge-carrier mobility, and consequently, photoreactivity of semiconductor photocatalysts. The conventional ...approach of modifying the electronic structure of a semiconductor photocatalyst for a wider absorption range by anion doping operates at the cost of reduced redox potentials and/or charge-carrier mobility, so that its photoreactivity is usually limited and some important reactions may not occur at all. Here, we report sulfur-doped graphitic C3N4 (C3N4−x S x ) with a unique electronic structure that displays an increased valence bandwidth in combination with an elevated conduction band minimum and a slightly reduced absorbance. The C3N4−x S x shows a photoreactivity of H2 evolution 7.2 and 8.0 times higher than C3N4 under λ > 300 and 420 nm, respectively. More strikingly, the complete oxidation process of phenol under λ > 400 nm can occur for sulfur-doped C3N4, which is impossible for C3N4 even under λ > 300 nm. The homogeneous substitution of sulfur for lattice nitrogen and a concomitant quantum confinement effect are identified as the cause of this unique electronic structure and, consequently, the excellent photoreactivity of C3N4−x S x . The results acquired may shed light on general doping strategies for designing potentially efficient photocatalysts.
This paper reports the synthesis of nanosized TiO2 single crystals with different percentages of exposed (001) facets in the presence of HF solution. Various characterizations are conducted to ...understand the correlation between particle morphology, exposed (001) facets and photo‐conversion efficiency of the nanosized anatase TiO2 single crystals. An enhancement in dye‐sensitized solar cells (DSSCs) overall conversion efficiency is observed for the photoanode consisting of nanosized TiO2 single crystals with higher percentage of exposed (001) facets, increasing from 7.47%, 8.14% to 8.49% for the TiO2 single crystals with ca. 10%, 38%, and 80% percentage of exposed (001) facets. Experimentally confirmed by dark current potential and open‐circuit voltage decay scans, such highly exposed (001) facets are not only favorable for more dye adsorption but also effectively retard the charge recombination process in DSSCs.
The correlation between nanosized anatase TiO2 single crystals with a tunable percentage of exposed (001) facets and their photoconversion efficiency was investigated. A considerable enhancement in the dye‐sensitized solar cell performance was observed for photoanode consisting of nanosized TiO2 single crystals with increased percentage of exposed (001) facets. It was evident that highly exposed (001) facets of TiO2 are not only favorable for dye adsorption but also effectively retard the charge recombination rate of DSSCs.
Design of multicomponent yolk–shell structures is crucial for the fabrication of micro/nanoreactors for a variety of applications. This work reports the rational design and synthesis of ...yolk–shell‐structured submicroreactors with loaded metal nanoparticles into ZnO–microporous carbon core–shell structures. The solvothermal treatment and carbonization process of uniform zeolitic imidazolate framework‐8 (ZIF‐8)@resin polymer core–shell structures leads to the generation of yolk–shell‐structured ZnO@carbon. The synthesis conditions are optimized to track the evolution of ZIF‐8 in a confined space of resin polymer as a submicroreactor itself. It is found that nanoribbon evolution occurs via the formation of the intermediate needle‐like particles. The Pd&ZnO@carbon submicroreactor is shown to be a highly selective catalyst (selectivity >99%) for hydrogenation of phenylacetylene to phenylethylene. The excellent performance of Pd&ZnO@carbon particles is evidenced by higher conversion and selectivity than that of Pd/ZnO and Pd/C with similar Pd loading. Furthermore, Pd&ZnO@carbon submicroreactors show superior catalytic stability, and no deactivation after 25 h of reaction. The proposed strategy is promising for the design of multifunctional micro/nanoreactors or nanocontainers for construction of artificial cells.
A unique transformation of Pd/ZIF‐8@polymer is achieved under hydrothermal conditions to generate Pd&ZnO@polymer submicroreactors, which are used to generate Pd&ZnO@carbon yolk–shell submicroreactors. They exhibit enhanced high catalytic activity and selectivity in the semihydrogenation of phenylacetylene.
Nanosized anatase TiO(2) single crystals with 18% {001} facets have a raised conduction band minimum by 0.1 eV, and exhibit photocatalytic activity both for generating *OH radicals and for splitting ...water into hydrogen that is markedly superior--by factors of 5.6 and 8.2, respectively--to reference ca. 3 microm anatase TiO(2) with 72% {001} facets.
We report a simple but efficient method to prepare stable homogeneous suspensions containing monodispersed MgAl layered double hydroxide (LDH) nanoparticles that have wide promising applications in ...cellular drug (gene) delivery, polymer/LDH nanocomposites, and LDH thin films for catalysis, gas separation, sensing, and electrochemical materials. This new method involves a fast coprecipitation followed by controlled hydrothermal treatment under different conditions and produces stable homogeneous LDH suspensions under variable hydrothermal treatment conditions. Moreover, the relationship between the LDH particle size and the hydrothermal treatment conditions (time, temperature, and concentration) has been systematically investigated, which indicates that the LDH particle size can be precisely controlled between 40 and 300 nm by adjusting these conditions. The reproducibility of making the identical suspensions under identical conditions has been confirmed with a number of experiments. The dispersion of agglomerated LDH aggregates into individual LDH crystallites during the hydrothermal treatment has been further discussed. This method has also been successfully applied to preparing stable homogeneous LDH suspensions containing various other metal ions such as Ni2+, Fe2+, Fe3+, Co2+, Cd2+, and Gd3+ in the hydroxide layers and many inorganic anions such as Cl-, CO3 2-, NO3 -, and SO4 2-.
Large pore mesoporous silica nanoparticles (LP-MSNs) functionalized with poly-l-lysine (PLL) were designed as a new carrier material for gene delivery applications. The synthesized LP-MSNs are ...100–200 nm in diameter and are composed of cage-like pores organized in a cubic mesostructure. The size of the cavities is about 28 nm with an entrance size of 13.4 nm. Successful grafting of PLL onto the silica surface through covalent immobilization was confirmed by X-ray photoelectron spectroscopy, solid-state 13C magic-angle spinning nuclear magnetic resonance, Fourier transformed infrared, and thermogravimetric analysis. As a result of the particle modification with PLL, a significant increase of the nanoparticle binding capacity for oligo-DNAs was observed compared to the native unmodified silica particles. Consequently, PLL-functionalized nanoparticles exhibited a strong ability to deliver oligo DNA-Cy3 (a model for siRNA) to Hela cells. Furthermore, PLL-functionalized nanoparticles were proven to be superior as gene carriers compared to amino-functionalized nanoparticles and the native nanoparticles. The system was tested to deliver functional siRNA against minibrain-related kinase and polo-like kinase 1 in osteosarcoma cancer cells. Here, the functionalized particles demonstrated great potential for efficient gene transfer into cancer cells as a decrease of the cellular viability of the osteosarcoma cancer cells was induced. Moreover, the PLL-modified silica nanoparticles also exhibit a high biocompatibility, with low cytotoxicity observed up to 100 μg/mL.
The practical applications of solar-driven water splitting pivot on significant advances that enable scalable production of robust photoactive films. Here, we propose a proof-of-concept for ...fabricating robust photoactive films by a particle-implanting technique (PiP) which embeds semiconductor photoabsorbers in the liquid metal. The strong semiconductor/metal interaction enables resulting films efficient collection of photogenerated charges and superior photoactivity. A photoanode of liquid-metal embraced BiVO
can stably operate over 120 h and retain ~ 70% of activity when scaled from 1 to 64 cm
. Furthermore, a Z-scheme photocatalyst film of liquid-metal embraced BiVO
and Rh-doped SrTiO
particles can drive overall water splitting under visible light, delivering an activity 2.9 times higher than that of the control film with gold support and a 110 h stability. These results demonstrate the advantages of the PiP technique in constructing robust and efficient photoactive films for artificial photosynthesis.
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