Enhanced electrochemical performance of hydrous RuO₂/mesoporous carbon nanocomposites via nitrogen doping

Hydrous RuO₂ nanoparticles have been uniformly deposited onto nitrogen-enriched mesoporous carbons (NMCs) via a facile hydrothermal method. The nitrogen doping in the carbon framework not only provides reversible pseudocapacitance but also guides uniform deposition of RuO₂ nanoparticles. As a result, an extremely high specific capacitance of 1733 F/g per RuO₂, comparable to the theoretic capacitance of RuO₂, is reached when 4.3 wt % of RuO₂·1.25H₂O is loaded onto the NMCs. Systematic studies show that either nitrogen-free or excess nitrogen doping result in RuO₂ clusters formation and worsen the electrochemical performances. With intermediate nitrogen and RuO₂ content (8.1 wt % N, 29.6 wt % of RuO₂·1.25H₂O), the composites deliver excellent power performance and high specific capacitance (402 F/g) with reversible capacitive response at 500 mV/s. The unique properties of nitrogen in textual, morphological, and electrochemical aspects may also provide further understanding about the effects of nitrogen doping and metal oxide deposition on supercapacitor performance.