Ultrasmall, crystalline, and dispersible NiO nanoparticles are prepared for the first time, and it is shown that they are promising candidates as catalysts for electrochemical water oxidation. Using a solvothermal reaction in tert-butanol, very small nickel oxide nanocrystals can be made with sizes tunable from 2.5 to 5 nm and a narrow particle size distribution. The crystals are perfectly dispersible in ethanol even after drying, giving stable transparent colloidal dispersions. The structure of the nanocrystals corresponds to phase-pure stoichiometric nickel(ii) oxide with a partially oxidized surface exhibiting Ni(iii) states. The 3.3 nm nanoparticles demonstrate a remarkably high turn-over frequency of 0.29 s–1 at an overpotential of g = 300 mV for electrochemical water oxidation, outperforming even expensive rare earth iridium oxide catalysts. The unique features of these NiO nanocrystals provide great potential for the preparation of novel composite materials with applications in the field of (photo)electrochemical water splitting. The dispersed colloidal solutions may also find other applications, such as the preparation of uniform hole-conducting layers for organic solar cells.
Gold has always been the one precious material people like best. Due to its intrinsic value, buying the yellow metal has been seen as a good way of securing one’s money. Big players on the market prefer it in the form of bullion, whereas small investors settle themselves with purchasing fine pieces of gold jewelry. In modern times though, gold has ceased to be merely a safe investment opportunity or exchange currency. As a result of extensive research and continuous development, it has been discovered that gold can be used successfully for scientific purposes as well.
One of these special uses of gold refers to what is called ‘nanogold’, ‘colloidal gold’ or ‘gold nanoparticles’, i.e. sub-micrometer-sized particles of gold dispersed in a fluid, usually water. The existence of these special gold particles has been known to people since ancient times, yet it was in 1850s that scientists focused their full attention on them. The main reasons behind this interest for gold nanoparticles are their extraordinary optical, electronic and molecular-recognition properties. These properties allow for the gold nanoparticles to have applications in various fields, including electron microscopy, electronics,Nickel Oxide Nanoparticles,nanotechnology and materials science.
Biological electronic microscopy is one of the areas where gold nanoparticles have been extensively used as contrast agents. They can be associated with many traditional biological probes such as antibodies, lectins, superantigens, glycans, nucleic acids and receptors. Because gold particles having various sizes can be easily spotted in electron micrographs, it is possible for multiple experiments to be conducted simultaneously.
In what concerns the domain of health and medical applications, gold nanoparticles have been successfully used as part of the treatment for some diseases. Rheumatoid arthritis was among the first conditions where use of gold was part of the therapy since it has been found that gold particles implanted near the arthritic hip joints relieve pain. There have also been some in vitro experiments which have proved that gold nanoparticles combined with microwave radiation can destroy the beta-amyloid fibrils and plaque which are characteristic for Alzheimer’s disease. But perhaps the most important medical purpose for which gold nanoparticles can be used is the localization and treatment of cancer. It has already been shown that by directing gold nanoparticles into the nuclei of cancer cells, they can only not hinder them from multiplying, but also kill them.
As we can see, for the modern society of today gold has become more than just merchandise and by buying it we do not just secure our investments, but our health as well. With the help of science, researchers have been able to explore the great latent potential gold has. Just like the professionals in the business whose opinion is of great value for the buyers, specialists in important areas such as medicine can testify about gold’s benefits too.
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