Using in situ indentation, we show that highly localized and well-defined mechanical deformation can be coupled with structural and electronic characterization in the scanning tunneling microscope. Dislocations induced in Ni(100) were topographically imaged and probed by scanning tunneling spectroscopy to assess their effect on local surface electronic structure. Compared with undamaged terraces, dislocation regions exhibited a significant increase in local density of states near the Fermi level, and enhanced reactivity toward oxidation. In the context of the d-band electronic structure model, we suggest that the undercoordination of atoms and residual strain resulting from plastic deformation serve to locally accelerate adsorption-driven chemical reactions with species such as molecular oxygen.

We report an easy way to assemble porous one-dimensional (1D) Ni2P nanowires through phosphatization of a Ni(SO4)0.3(OH)1.4 nanobelt precursor. The peculiar synthetic process endows the Ni2P nanowires with large surface area, hierarchical porous structure and the ability to form closely connected network for transporting both electrons and electrolytes, which in conjunction with the high intrinsic electrocatalytic activity make it an excellent low-cost counter electrode material for dye-sensitized solar cells (DSSCs). Indeed, the first investigation of such novel counter electrode for DSSC presented superb photovoltaic performance rivaling the conventional Pt counter electrode.

Development of universal biosensors based on electrical readout is currently limited by the difficulty of electrical signal transduction upon capture of neutral analytes. Kelley and co-workers demonstrate an elegant approach wherein an amplified electrical current flows to a multiplexed electrode array in proportion with the binding of nucleic acids, proteins, and small molecules—regardless of their inherent charge. Here we present a commentary on the strengths and limitations of this method.

A quantitative correlation between R-line luminescence at around 1.37 µm and {311} defect nature, size and concentration has been undertaken in silicon, following keV Si-implantation and subsequent annealing using photoluminescence spectroscopy and plan-view transmission electron microscopy. The formation and evolution of the rod-like defects were found to be dependent on annealing time at a temperature of 700 °C, but there was no simple correlation found between the density and size of those defects and the R-line intensity. In particular, whereas the presence of {311} defects is essential for observing R-line luminescence, both very small {311} defects at short annealing times and fully developed {311} defects at long annealing times do not contribute to such luminescence. We provide possible explanations for this behavior and suggest that the local (strain) environment around defects, the dopant level and impurities in the silicon substrate may all play a role in determining R-line intensity.

Quantum simulations of oxygen incorporation at a Σ5 grain boundary in yttria-stabilized zirconia (YSZ), a common solid oxide fuel cells (SOFCs) electrolyte, show that the incorporation energy is reduced compared with YSZ with no grain boundaries. The simulation results are supported by electrochemical impedance spectroscopy (EIS) measurements conducted on a single crystalline YSZ substrate with nanogranular interlayered YSZ. EIS results showed that single crystalline YSZ membranes with nanogranular surface (i.e., high grain boundary densities) exhibit small electrode impedances than the reference single crystalline YSZ. The 20-nm-thick nanogranular YSZ interlayer was fabricated by atomic layer deposition and the performance for SOFCs with nanograined interlayer was increased by factor of 2 at operating temperatures between 350 and 450 °C.

Biogenic minerals often contain inorganic and organic impurities that are believed to harden and toughen the material. However, because of the complexity of these systems, it is difficult to deconvolute the effect of each of these impurities on the hardness of the material. We have created single-crystal samples with a range of magnesium concentrations and measured their hardness while controlling for orientation. We find that hardness increases linearly with magnesium content and that magnesium impurities could account for ~20% of the increased hardness in biogenic calcite from the mollusk Atrina rigida when compared with pure geologic calcite.