Metal carbides are fascinating materials that have a wide range of uses. Transition metal carbides are perhaps the most important and well known carbides as they are widely employed as hard and chemically stable coatings for things like drill bits.
More recently, transition metal carbides have attracted interest for their catalytic properties. For this, nanoparticles of the transition metal carbide are needed to maximise the surface area. The challenge is that transition metal carbides are ceramic materials. They are traditionally synthesized by combining metal or metal oxide powders with graphite and heating to very high temperatures (often >1000 °C). The conditions of the synthesis mean that the metal carbide particles that are produced tend to be large, irregularly-shaped and sintered into large agglomerates. One of the aims of the research in the SusNano project was to develop routes to nanoparticulate metal carbides using sol-gel chemistry.
Sol-gel chemistry uses solution-state precursors to prepare solid-state materials. The advantage of sol-gel chemistry is that you start with a homogeneous mixture of precursors. In ceramic synthesis, this means that you tend to produce small particles. The organic matrix of the sol-gel precursor keeps the inorganic precursors separate so that the nucleation and growth of the ceramic is constrained. For a detailed overview of sol-gel chemistry check out our review article here.
In our SusNano project, we have used biopolymers to prepare nanoparticles of various metal carbides, including iron carbide and tungsten carbide. The tungsten carbide work is being prepared for publication – watch this space! To learn more about how we have studied the formation of our nanoparticles check out our page on mechanisms here.