Spontaneous hydrogen production using gadolinium telluride.

Developing materials for controlled hydrogen production through water splitting is one of the most promising ways to meet current energy demand. Here, we demonstrate spontaneous and green production of hydrogen at high evolution rate using gadolinium telluride (GdTe) under ambient conditions. The spent materials can be reused after melting, which regain the original activity of the pristine sample. The phase formation and reusability are supported by the thermodynamics calculations. The theoretical calculation reveals ultralow activation energy for hydrogen production using GdTe caused by charge transfer from Te to Gd. Production of highly pure and instantaneous hydrogen by GdTe could accelerate green and sustainable energy conversion technologies.

Transformation in band energetics of CuO nanoparticles as a function of solubility and its impact on cellular response.

Nanoparticles under a reactive microenvironment, have the propensity to undergo morphological and compositional changes, which can translate into band edge widening. Although cell membrane depolarization has been linked with the electronic band structure of nanomaterials in their native state, the change in band structure as a consequence of a soluble nanoparticle system is less studied. Therefore we studied the consequence of dissolution of CuO nanoparticles on the band structure and flat band potentials and correlated it with its ability to induce a intracellular oxidative stress. The temporal variation in bandgap, fermi energy level and valence band maxima were evaluated on the remnant CuO nanoparticles post dissolution. CuO nanoparticles showed a very high dissolution in simulated body fluid (51%) and cell culture media (75%). This dissolution resulted in an in situ physico-chemical transformation of CuO nanoparticles. A temporal increase in the bandgap energy as a result of media interaction was up to 107%. Temporal variation in the flat band potentials with the generation of intracellular ROS, cell viability, late and early apoptosis in addition to necrosis on RAW 264.7 cells was established due to biological redox potential overlap. The mRNA expression for TNF-α, IL-6, IL-1ß and IL-10 in response to the particle treatment was also evalulated for 6 hours. Through this study, we establish that the toxicological potential of CuO nanoparticles is a temporal function of band energies (its overlap with the intracellular redox potential) followed by release of ionic species in the cytotoxic regime.

Core-shell Au@AuAg nano-peanuts for the catalytic reduction of 4-nitrophenol: critical role of hollow interior and broken shell structure.

Bimetallic hollow core-shell nanoparticles have gained immense attention, especially as a high-performance catalyst due to their large surface area and increased number of uncoordinated atoms. However, the synthesis of an anisotropic hollow structure with large number of uncoordinated atoms and tailored hole size remains elusive. Herein, we report the synthesis of peanut-like core-shell nanostructures consisting of Au nanorods as the core covered by the AuAg alloy shell. The AuAg shell was formed on the Au nanorod core via co-deposition of Ag and Au atoms without disturbing the Au nanorod core. Then, we controllably and selectively removed Ag atoms from the shell to create "Broken Shell Peanuts" with variable hole size between 8 ± 4 nm and 26 ± 7 nm. Further, we utilized these nanostructures with different hole size as catalysts to reduce 4-nitrophenol to 4-aminophenol where the broken shell peanut nanostructures with a hole size of 26 ± 7 nm were found to be 12 times more efficient than the solid shell peanut structures.

Synthesis of Complex Nanoparticle Geometries via pH-Controlled Overgrowth of Gold Nanorods.

We show that many complex gold nanostructures such as the water chestnut, dog bone, nanobar, and octahedron, which are not easily accessible via a direct seed-growth synthesis approach, can be prepared via overgrowth of the same gold nanorods by varying pH and Ag concentrations in the growth solution. Overgrown nanostructures' shapes were determined by the rate of gold atom deposition, which is faster at higher pH. In the presence of AgNO3, codeposition of gold and silver atoms affects the shapes of overgrown nanostructures, particularly at high pH.