When Size Really Matters: Size-Dependent Properties and Surface Chemistry of Metal and Metal Oxide Nanoparticles in Gas and Liquid Phase Environments†

It is clear if one peruses the pages of The Journal of Physical Chemistry and other journals of the American Chemical Society that in the years around the beginning of the twenty first century, and in particular the year two thousand eight, there is a great deal of interest in the physical chemistry of nanoparticles. In this article, the focus is on some of the interesting and often not well understood size-dependent properties and surface chemistry of metal and metal oxide nanoparticles in gas and liquid phase environments. Challenges that remain and suggestions for future research needs are also presented at the end of this article.