Structures and electrochemical capacitive properties of RuO2 vertical nanorods encased in hydrous RuO2

Structural electrodes of anhydrous RuO2 vertical nanorods encased in hydrous RuO2 have been prepared via chemical vapor deposition (CVD) followed by electrochemical deposition. The composite structures are studied using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The capacitive properties are measured using cyclic voltammetry and impedance spectroscopy. In a miniaturized configuration, the CVD grown structure provides a connecting backbone of electron paths and open channels for ion migration to facilitate the charge delivery or acceptance from the electrodeposited hydrous RuO2 of high pseudocapacitance. The sample of thermally reduced nanorods encased in RuO2 center dot 0.46H(2)O (RuRuO2VR-H2) exhibits a total capacitance of similar to 520 F g(-1) (870 mF cm(-2)) at 5 mV s(-1), superior to that of the RuO2 center dot 0.46H(2)O coated as-grown nanorods (RuO2VR-H) similar to 260 F g(-1) (300 mF cm(-2)). Despite having twice the charge storage capability, RuRuO2VR-H2 demonstrates a capacitor response time similar to that of RuO2VR-H because of its low internal resistance. Two important features of RuRuO2VR-H2 are identified, including an open structure for hydrous RuO2 accommodation and a fast electron path for charge delivery and retrieval.