As antibiotic resistance continues to be a major public health problem, antimicrobial alternatives have become critically important. Nanostructured zeolites have been considered as an ideal host for improving popular antimicrobial silver-ion-exchanged zeolites, because with very short diffusion path lengths they offer advantages in ion diffusion and release over their conventional microsized zeolite counterparts. Herein, comprehensive studies are reported on materials characteristics, silver-ion release kinetics, and antibacterial properties of silver-ion-exchanged nanostructured zeolite X with comparisons to conventional microsized silver-ion-exchanged zeolite (∼2 μm) as a reference. The nanostructured zeolites are submicrometer-sized aggregates (100–700 nm) made up of primary zeolite particles with an average primary particle size of 24 nm. The silver-ion-exchanged nanostructured zeolite released twice the concentration of silver ions at a rate approximately three times faster than the reference. The material exhibited rapid antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 4 to 16 μg/mL after 24 h exposure in various growth media and a minimum bactericidal concentration (MBC; >99.9% population reduction) of 1 μg/mL after 2 h in water. While high concentrations of silver-ion-exchanged nanostructured zeolite X were ineffective at reducing MRSA biofilm cell viability, efficacy increased at lower concentrations. In consideration of potential medical applications, cytotoxicity of the silver-ion-exchanged nanostructured zeolite X was also investigated. After 4 days of incubation, significant reduction in eukaryotic cell viability was observed only at concentrations 4–16-fold greater than the 24 h MIC, indicating low cytotoxicity of the material. Our results establish silver-ion-exchanged nanostructured zeolites as an effective antibacterial material against dangerous antibiotic-resistant bacteria.Keywords: antibacterial; antimicrobial; antimicrobial susceptibility; methicillin-resistant Staphylococcus aureus; MRSA; nanostructured zeolites; rapid ion release kinetics; silver;

Housing bio-nano guest devices based on DNA nanostructures within porous, conducting, inorganic host materials promise valuable applications in solar energy conversion, chemical catalysis, and analyte sensing. Herein, we report a single-template synthetic development of hierarchically porous, transparent conductive metal oxide coatings whose pores are freely accessible by large biomacromolecules. Their hierarchal pore structure is bimodal with a larger number of closely packed open macropores (∼200 nm) at the higher rank and with the remaining space being filled with a gel network of antimony-doped tin oxide (ATO) nanoparticles that is highly porous with a broad size range of textual pores mainly from 20–100 nm at the lower rank. The employed carbon black template not only creates the large open macropores but also retains the highly structured gel network as holey pore walls. Single molecule fluorescence microscopic studies with fluorophore-labeled DNA nanotweezers reveal a detailed view of multimodal diffusion dynamics of the biomacromolecules inside the hierarchically porous structure. Two diffusion constants were parsed from trajectory analyses that were attributed to free diffusion (diffusion constant D = 2.2 μm2/s) and to diffusion within an average confinement length of 210 nm (D = 0.12 μm2/s), consistent with the average macropore size of the coating. Despite its holey nature, the ATO gel network acts as an efficient barrier to the diffusion of the DNA nanostructures, which is strongly indicative of physical interactions between the molecules and the pore nanostructure.

A photosynthetic reaction center (RC)-based electrode system is one of the most promising biomimetic approaches for solar energy transduction which is a renewable and environment-friendly source of energy. However, the instability of RCs in a non-cellular environment and the unfeasible scalability of electrode materials hamper the promising application of these systems. Herein, we report a highly stable and scalable RC-electrode system in which RCs are directly immobilized on a flexible and transparent mercapto reduced graphene oxide (mRGO) electrode. RCs immobilized on a mRGO film retain their photoactivity after twenty-week storage under darkness and even after 24 h continuous illumination at room temperature under aerobic conditions. The remarkable stability and mechanical flexibility of our system offer great potential for the development of a flexible RC-based biomimetic device for solar energy transduction.

•Hydrotalcites with vanadium prepared by coprecipitation and impregnation.•Crystallinity of HT is affected by the V presence.•Role of isolated vanadia species and polyvanadates in toluene steam reforming.The steam reforming of toluene has been studied on three catalysts with vanadium (0.9, 1.75, 3%) derived from hydrotalcites precursors (Mg/Al molar ratio 3) in the temperature range 400–500 °C. Catalysts were characterized by BET, XRD, SEM, TEM, FT-IR and then a correlation between physico-chemical characteristics and catalytic activity for toluene steam reforming has been done. The results showed that the catalyst with 3% V, with polyvanadate species, achieves the best catalytic activity, with a toluene conversion of 77.5%, at 500 °C, and a H2 composition of 57%.

We report the synthesis and characterization of hydroxycancrinite zeolite nanorods by a simple hydrothermal treatment of aluminosilicate hydrogels at high concentrations of precursors without the use of structure-directing agents. Transmission electron microscopy (TEM) analysis reveals that cancrinite nanorods, with lengths of 200–800 nm and diameters of 30–50 nm, exhibit a hexagonal morphology and are elongated along the crystallographic c direction. The powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) and TEM studies revealed sequential events of hydrogel formation, the formation of aggregated sodalite nuclei, the conversion of sodalite to cancrinite and finally the growth of cancrinite nanorods into discrete particles. The aqueous dispersion of the discrete nanorods displays a good stability between pH 6–12 with the zeta potential no greater than −30 mV. The synthesis is unique in that the initial aggregated nanocrystals do not grow into microsized particles (aggregative growth) but into discrete nanorods. Our findings demonstrate an unconventional possibility that discrete zeolite nanocrystals could be produced from a concentrated hydrogel.

The potential electrochromic application of graphene-based nanohybrids is hampered by the challenges in interfacing the electrochromic nanoparticles with graphene at atomic scale and in fabricating their thin film on the substrate through a scalable method. In an effort to overcome these challenges, we demonstrate a highly dispersible graphene-based molybdenum oxide nanohybrid (mRGO-MoO3–x) for flexible electrochromic application. With only a squeeze pipet, mRGO-MoO3–x could be deposited with a high coverage on various substrates through a scalable equipment-free Langmuir–Blodgett film deposition method. By taking advantage of high transmittance benefited from its remarkable thinness, the mRGO-MoO3–x Langmuir–Blodgett film shows a superior reversible electrochromic property with high coloration efficiency on both hard and flexible substrates.Keywords: electrochromic materials; electrodes; hybrid materials; Langmuir−Blodgett; molybdenum

By the establishment of highly controllable synthetic routes, electronic band-edge energies of the n-type transparent semiconductor Zr-doped anatase TiO2 have been studied holistically for the first time up to 30 atom % Zr, employing powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen gas sorption measurements, UV/vis spectroscopies, and Mott–Schottky measurements. The materials were produced through a sol–gel synthetic procedure that ensures good compositional homogeneity of the materials, while introducing nanoporosity in the structure, by achieving a mild calcination condition. Vegard’s law was discovered among the homogeneous samples, and correlations were established between the chemical compositions and optical and electronic properties of the materials. Up to 20% Zr doping, the optical energy gap increases to 3.29 eV (vs 3.19 eV for TiO2), and the absolute conduction band-edge energy increases to −3.90 eV (vs −4.14 eV). The energy changes of the conduction band edge are more drastic than what is expected from the average electronegativities of the compounds, which may be due to the unnatural coordination environment around Zr in the anatase phase.

Nanoporous structures of a p-type semiconductor, delafossite CuAlO2, with a high crystallinity have been fabricated through an inorganic/polymer double-gel process and characterized for the first time via Mott–Schottky measurements. The effect of the precursor concentration, calcination temperature, and atmosphere were examined to achieve high crystallinity and photoelectrochemical properties while maximizing the porosity. The optical properties of the nanoporous CuAlO2 are in good agreement with the literature with an optical band gap of 3.9 eV, and the observed high electrical conductivity and hole concentrations conform to highly crystalline and well-sintered nanoparticles observed in the product. The Mott–Schottky plot from the electrochemical impedance spectroscopy studies indicates a flat-band potential of 0.49 V versus Ag/AgCl. It is concluded that CuAlO2 exhibits band energies very close to those of NiO but with electrical properties very desirable in the fabrication of photoelectrochemical devices including dye-sensitized solar cells.

A new class of highly active solid base catalysts for biodiesel production was developed by creating hierarchically porous aluminosilicate geopolymer with affordable precursors and modifying the material with varying amounts of calcium. For the catalysts containing ≥8 wt% Ca, almost 100% conversion has been achieved in one hour under refluxing conditions with methanol solvent, and the high catalytic activity was preserved for multiple regeneration cycles. Temperature-programed desorption studies of CO2 indicate that the new base catalyst has three different types of base sites on its surface whose strengths are intermediate between MgO and CaO. The detailed powder X-ray diffraction (PXRD) and X-ray photoelectron spectroscopic (XPS) studies show that the calcium ions were incorporated into the aluminosilicate network of the geopolymer structure, resulting in a very strong ionicity of the calcium and thus the strong basicity of the catalysts. Little presence of CaCO3 in the catalysts was indicated from the thermogravimetric analysis (TGA), XPS and Fourier transform infrared spectroscopy (FT-IR) studies, which may contribute to the observed high catalytic activity and regenerability. The results indicate that new geopolymer-based catalysts can be developed for cost-effective biodiesel production.

Nanoporous antimony-doped tin oxide (ATO) coatings with high surface area, optical transparency and electron transfer properties have been prepared using an interpenetrating inorganic–organic hybrid sol–gel approach. UV-Vis and X-ray photoelectron spectroscopic studies were carried out on the prepared materials in addition to the characterization of their microstructures with scanning electron microscopy, transmission electron microscopy, and nitrogen sorption experiments. Cyclic voltammetry (CV) and impedance spectroscopy were employed to characterize the electrochemical and electron transfer properties of the coatings in both acidic and neutral media with an Fe3+/Fe2+ redox couple. The material had a specific surface area of over 90 m2 g−1 with a bimodal pore distribution with two distinctive peaks at ca. 8 and 40 nm. The electrochemical capacitance of the material was about 100 times as high as the value obtained for a commercially available nonporous fluorine-doped tin oxide (FTO) electrode. The estimated electron transfer rate of the former was three times larger than that of the FTO. The optical transparency, high surface area and high electron transfer rate of the nanoporous ATO coatings make the material well suited for diverse photoelectrochemical applications.

Highly mesoporous antimony-doped tin oxide (ATO) materials with three-dimensionally connected textural pores were prepared by a convenient one-pot process by creating, drying and calcining hydrous ATO and resorcinol–formaldehyde composite gels. The synthesis is designed to form a hydrous ATO gel structure first at room temperature and upon subsequent heating at 70 °C the inorganic gel network catalyzes the full polymerization of resorcinol and formaldehyde. The resulting polymer network interpenetrates the inorganic gel network and serves as a hard template during drying and calcination. The final products show a good crystallinity and have high surface areas up to 100 m2 g−1 and high porosities up to 69%. The average pore sizes range from 7 to 33 nm, controlled mainly by varying the amount of the polymer component in the composite gels. The materials exhibit remarkably low resistivities (>0.14 Ω cm) for a mesoporous ATO material.

Stable immobilization of two redox proteins, cytochrome c and azurin, in a thin film of highly mesoporous antimony-doped tin oxide is demonstrated viaUV-vis spectroscopic and electrochemical investigation.

A conductive nanoporous antimony-doped tin oxide (ATO) powder has been prepared using the sol–gel method that contains three-dimensionally interconnected pores within the metal oxide and highly tunable pore sizes on the nanoscale. It is demonstrated that these porous materials possess the capability of hosting a tetrahedral-shaped DNA nanostructure of defined dimensions with high affinity. The tunability of pore size enables the porous substrate to selectively absorb the DNA nanostructures into the metal oxide cavities or exclude them from entering the surface layer. Both confocal fluorescence microscopy and solution FRET experiments revealed that the DNA nanostructures maintained their integrity upon the size-selective incorporation into the cavities of the porous materials. As DNA nanostructures can serve as a stable three-dimensional nanoscaffold for the coordination of electron transfer mediators, this work opens up new possibilities of incorporating functionalized DNA architectures as guest molecules to nanoporous conductive metal oxides for applications such as photovoltaics, sensors, and solar fuel cells.Keywords: antimony-doped tin oxide (ATO); conductive metal oxides; DNA nanocages; DNA nanotechnology; nanoporous materials

We present how the kinetic energy density (KED) can be interpreted on the basis of the orbital interactions within the Kohn−Sham theory and propose how to utilize a direct space function in chemical bonding analysis, the relative entropy density (RED), which is constructed from the KED, the Thomas−Fermi KED (TF-KED), and the electron density. From the detailed analysis of the KED of wave functions and the TF-KED from the free electron model, it is shown that the RED can reveal the nodal properties of individual wave functions and provide a variationally meaningful way of accumulating chemical bonding information from the wave functions, hence allowing quantitative bonding analysis in direct space. To substantiate the proposal, the RED function has been tested on the tetrahedral network solids, including the group 14 elements and the III−V binary compounds with the zinc blende structure. The direct space maps of the RED quantitatively reflect the trend in metallicity and the polarity of their two-center, two-electron bonds in terms of the absolute values of the RED, the location of the minimum values, and the behavior of the deformation from the spherical symmetry of the atomic RED.

By employing B2Se3 as a selenium source, we demonstrate that at reaction temperatures as low as 60 °C, relatively monodisperse, fluorescent CdSe nanocrystals can be conveniently prepared in various sizes selected from 2 to 13 nm.

Composite materials of hierarchically porous geopolymer and amorphous hydrous ferric oxide were produced and characterized as a new potentially cost-effective arsenic adsorbent. The arsenic removal capabilities of the iron (hydr)oxide (HFO) media were carried out using batch reactor experiments and laboratory scale continuous flow experiments. The Rapid Small-Scale Column Tests (RSSCT) were employed to mimic a scaled up packed bed reactor and the toxicity characteristic leaching procedure (TCLP) test of arsenic adsorbed solid material was carried out to investigate the mechanical robustness of the adsorbent. The best performing media which contained ~20 wt% Fe could remove over 95 µg of arsenic per gram of dry media from arsenic only water matric. The role of the high porosity in arsenic adsorption characteristics was further quantified in conjunction with accessibility of the adsorption sites. The new hierarchically porous geopolymer-based composites were shown to be a good candidate for cost-effective removal of arsenic from contaminated water under realistic conditions owing to their favorable adsorption capacity and very low leachability.

Composite materials of hierarchically porous geopolymer and amorphous hydrous ferric oxide were produced and characterized as a new potentially cost-effective arsenic adsorbent. The arsenic removal capabilities of the iron (hydr)oxide (HFO) media were carried out using batch reactor experiments and laboratory scale continuous flow experiments. The Rapid Small-Scale Column Tests (RSSCT) were employed to mimic a scaled up packed bed reactor and the toxicity characteristic leaching procedure (TCLP) test of arsenic adsorbed solid material was carried out to investigate the mechanical robustness of the adsorbent. The best performing media which contained ~20 wt% Fe could remove over 95 µg of arsenic per gram of dry media from arsenic only water matric. The role of the high porosity in arsenic adsorption characteristics was further quantified in conjunction with accessibility of the adsorption sites. The new hierarchically porous geopolymer-based composites were shown to be a good candidate for cost-effective removal of arsenic from contaminated water under realistic conditions owing to their favorable adsorption capacity and very low leachability.

Stable immobilization of two redox proteins, cytochrome c and azurin, in a thin film of highly mesoporous antimony-doped tin oxide is demonstrated viaUV-vis spectroscopic and electrochemical investigation.

Highly mesoporous antimony-doped tin oxide (ATO) materials with three-dimensionally connected textural pores were prepared by a convenient one-pot process by creating, drying and calcining hydrous ATO and resorcinol–formaldehyde composite gels. The synthesis is designed to form a hydrous ATO gel structure first at room temperature and upon subsequent heating at 70 °C the inorganic gel network catalyzes the full polymerization of resorcinol and formaldehyde. The resulting polymer network interpenetrates the inorganic gel network and serves as a hard template during drying and calcination. The final products show a good crystallinity and have high surface areas up to 100 m2 g−1 and high porosities up to 69%. The average pore sizes range from 7 to 33 nm, controlled mainly by varying the amount of the polymer component in the composite gels. The materials exhibit remarkably low resistivities (>0.14 Ω cm) for a mesoporous ATO material.

A photosynthetic reaction center (RC)-based electrode system is one of the most promising biomimetic approaches for solar energy transduction which is a renewable and environment-friendly source of energy. However, the instability of RCs in a non-cellular environment and the unfeasible scalability of electrode materials hamper the promising application of these systems. Herein, we report a highly stable and scalable RC-electrode system in which RCs are directly immobilized on a flexible and transparent mercapto reduced graphene oxide (mRGO) electrode. RCs immobilized on a mRGO film retain their photoactivity after twenty-week storage under darkness and even after 24 h continuous illumination at room temperature under aerobic conditions. The remarkable stability and mechanical flexibility of our system offer great potential for the development of a flexible RC-based biomimetic device for solar energy transduction.

Nanoporous antimony-doped tin oxide (ATO) coatings with high surface area, optical transparency and electron transfer properties have been prepared using an interpenetrating inorganic–organic hybrid sol–gel approach. UV-Vis and X-ray photoelectron spectroscopic studies were carried out on the prepared materials in addition to the characterization of their microstructures with scanning electron microscopy, transmission electron microscopy, and nitrogen sorption experiments. Cyclic voltammetry (CV) and impedance spectroscopy were employed to characterize the electrochemical and electron transfer properties of the coatings in both acidic and neutral media with an Fe3+/Fe2+ redox couple. The material had a specific surface area of over 90 m2 g−1 with a bimodal pore distribution with two distinctive peaks at ca. 8 and 40 nm. The electrochemical capacitance of the material was about 100 times as high as the value obtained for a commercially available nonporous fluorine-doped tin oxide (FTO) electrode. The estimated electron transfer rate of the former was three times larger than that of the FTO. The optical transparency, high surface area and high electron transfer rate of the nanoporous ATO coatings make the material well suited for diverse photoelectrochemical applications.