Diamond Particles as a Platform for Growth of Extended Solids

<br/>A method using an atmospheric pressure plasma system to convert the gas CO into an extended solid is being developed by Rivis Inc. Dendritic deposits of cauliflower structures result from treatment of CO in a dielectric barrier discharge (DBD) system. Deposits that accumulate on the dielectric barrier material and bare metal electrode may be collected for subsequent use. Extended solids are materials that are typically formed at extremely high pressure and temperature using methods that severely limit the amount of material that can be produced. The use of a DBD plasma system is important in that it is a non-equilibrium plasma that allow one to maintain electrode temperatures <u>&lt; </u>30°C with cooling even at high discharge powers and high frequency operation. This allows one to deposit the temperature sensitive materials for collection. To increase the deposition rate, we are exploring the use of diamond particles as substrates for deposition of the extended solids. The benefits of using a particulate substrate versus a planar substrate include: (i) significantly increased deposition surface area as compared to a planar surface; (ii) ease and convenience for collection and storage of the final product. The coated particles can be easily removed and transferred to a solvent or used as-is. Use of diamond particles is motivated due to their superior inertness as compared to other candidate materials when exposed to the reactive plasma conditions. Even though diamond is known to be stable to even harsh chemical conditions, it is readily functionalized which contributes to good adherence of the carbon sub(oxide) (COx) extended solids. Upon optimization of the plasma parameters (power, frequency, gas composition and flow rate) for the most efficient COx growth, particle size, amount of particles, particle surface composition and particles placement in the reactor are particle-specific parameters for optimization which will be discussed. Particularly, particle size is an important parameter in two regards: (i) in the process of nucleation and growth of COx (compatibility of the feature sizes between deposit/substrate at a microscale) and (ii) resulting substrate area increase for the COx growth. We will report results of the investigation of particle size dependent growth over the size range from 100 nm to 100 um, and the most suitable parameters for the growth of CO-based extended solids on particulate diamond substrates.