Assembling complex nanostructures on functional substrates such as electrodes promises new multi‐functional interfaces with synergetic properties capable of integration into larger‐scale devices. Here, we report a microemulsion‐mediated process for the preparation of CuO/Cu electrodes comprising a surface layer of a densely packed array of unusual cog‐shaped CuO microparticles with hierarchical nanofilament‐based superstructure and enhanced electrochemical performance in lithium‐ion batteries. The CuO particles are produced by thermolysis of Cu(OH)2 micro‐cog precursors that spontaneously assemble on the copper substrate when the metal foil is treated with a reactive oil‐based microemulsion containing nanometer‐scale aqueous droplets. The formation of the hierarchical superstructure improves the coulombic efficiency, specific capacity, and cycling performance compared with anodes based on CuO nanorods or polymer‐blended commercial CuO/C black powders, and the values for the initial discharge capacity (1052 mA h g−1) and reversible capacity (810 m A h g−1) are higher than most copper oxide materials used in lithium‐ion batteries. The results indicate that a fabrication strategy based on self‐assembly within confined reaction media, rather than direct synthesis in bulk solution, offers a new approach to the design of electrode surface structures for potential development in a wide range of materials applications.

Hexavalent chromium (Cr(VI)) contamination in drinking water resources remains a challenge in many parts of the United States, as well as in regions affected by industrial pollution. In this study, we demonstrated how electrically conducting carbon nanotube (CNT)polyvinyl alcohol (PVA) composite ultrafiltration (UF) membranes can be used to remove Cr(VI) from water through a combined process of electrostatic repulsion, electrochemical reduction, and precipitation. The impact of different operational (flux, contact time, applied electrical potential) and environmental (pH and salinity) conditions on Cr(VI) removal were evaluated. Due to the native electrical potential of the CNT/PVA UF membrane material, approximately 45% removal of 1 ppm Cr(VI) solution was detected under neutral pH conditions in deionized water. Increased Cr(VI) removal was observed with increasing membrane surface charge density, which was accomplished through the application of an external potential (3V, 5V and 7V, membrane as cathode) to the electrically conductive membrane surface. The solution ionic strength showed a significant impact on Cr(VI) removal. By increasing the ionic strength without applying external potential on the membrane, the electrostatic repulsive force between the charged membrane surface and the CrO 4 2ion was eliminated, and Cr(VI) removal dropped to zero. The highest removal (95%) was achieved when 7V was applied to the membrane/counter electrode with a 6 µm-thick membrane. Here, Cr(VI) was electrochemically reduced to Cr(III) on the membrane surface, followed by Cr(III) precipitation as chromium hydroxide Cr(OH) 3(s) , which occurred by Cr(III) reacting with hydroxide ions generated via water splitting on the CNT network. Precipitated Cr(OH) 3 was then removed by the UF membrane. In addition, CNT-PVA UF membranes were used to treat tap water spiked with Cr(VI); under these conditions, 99% Cr(VI) removal was observed when 7V were applied to the membrane/counter electrode. Furthermore, we demonstrate that other trace inorganic contaminants, such as uranium, were effectively removed as well.

The spherical form (s-form) of a genetically-modified gold-binding M13 bacteriophage was investigated as a scaffold for gold synthesis. Repeated mixing of the phage with chloroform caused a 15-fold contraction from a nearly one micron long filament to an approximately 60 nm diameter spheroid. The geometry of the viral template and the helicity of its major coat protein were monitored throughout the transformation process using electron microscopy and circular dichroism spectroscopy, respectively. The transformed virus, which retained both its gold-binding and mineralization properties, was used to assemble gold colloid clusters and synthesize gold nanostructures. Spheroid-templated gold synthesis products differed in morphology from filament-templated ones. Spike-like structures protruded from the spherical template while isotropic particles developed on the filamentous template. Using inductively coupled plasma-mass spectroscopy (ICP-MS), gold ion adsorption was found to be comparatively high for the gold-binding M13 spheroid, and likely contributed to the dissimilar gold morphology. Template contraction was believed to modify the density, as well as the avidity of gold-binding peptides on the scaffold surface. The use of the s-form of the M13 bacteriophage significantly expands the templating capabilities of this viral platform and introduces the potential for further morphological control of a variety of inorganic material systems.

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