\documentclass{article}
\usepackage{fontspec}
\defaultfontfeatures{Extension = .otf} % this is needed because
                                       % fontawesome package loads by
                                       % font name only
\usepackage{fontawesome}

\begin{document}
Cloud \faCloud

Cog \faCog

Database \faDatabase

Leaf \faLeaf
\end{document}
