Application of Ruthenium Nitride Deposited on Multi-walled Carbon Nanotube Forest as Electrode Material for Supercapacitors

Electrochemical capacitors (EC) or so-called supercapacitors are emerging class of electrochemical energy storage, which demonstrate high power densities and moderate energy densities. ECs are proved to be highly beneficial in different energy storage systems such as smart grids. To increase ECs energy density, pseudocapacitive materials (i.e., transition metals) that take advantage of fast and reversible surface Faradaic reactions for the accommodation of charges are utilized. Among various transition metal compounds, RuO2 exhibits a very high capacitance. However, transition metal nitrides (e.g., VN) have attracted much attention due to their promising mechanical properties and high electrical conductivity when compared to their oxide counterparts. Here, we first grow multi-walled carbon nanotubes (MWCNTs) with a forest-like structure on a stainless-steel 316L mesh by chemical vapor deposition. MWCNTs are used as a support material with high electrical conductivity, high specific surface area, and high electrochemical stability that exhibit an electrochemical double layer capacitance. Then, RuNx thin coatings are deposited by radio frequency plasma-assisted pulsed laser deposition (PAPLD) and atomic layer deposition (ALD) techniques. The results of X-ray photoelectron spectroscopy confirm a successful deposition of RuNx on the silicon substrate. The capacitance of the electrodes is calculated in in 1M KOH electrolyte and a high capacitance of 728 F g−1 is achieved.