  The fabrication method of diamond nanostructures can be divided into two
categories: top-down etching and bottom-growth. The early work on 3D
micro-structured diamond dates back to mid-1990s, using chemical vapor
infiltration (CVI) techniques. In this technology, carbon or carbide fibers
were typically used as the growth template. Almost in parallel, reactive ion
etching (RIE) was applied to achieve diamond surface nanostructuring. After
that the diamond surface nanostructures, typically vertically aligned diamond
nanowires (or nanorods) has been mainly fabricated using top-down plasma
etching techniques. In recent year, the templated diamond growth has gained
increasing attention due to the wide choice of template, mask-free production,
and unlimited surface enlargement. In this chapter, the development and main
techniques used in these two approaches will be elaborated. Nevertheless, other
less common methods, such as catalytic etching by metal particles, steam
activation and selective materials removal will also be discussed. As indicated
by the title, this chapter will mainly deal with the application of micro- and
nanostructured diamond in electrochemistry. In these applications, the
advantage of nanostructured diamond can be divided into three aspects: 1)
providing enlarged surface area for charge storage and catalyst deposition; 2)
tip-enhanced electrochemical reactions used in sensing applications; 3) diamond
membranes with micro- or nanopores can be applied in the electrochemistry
separation and purification applications. Examples and explanations on these
applications will be given in this chapter.
