ALD ruthenium oxide-carbon nanotube electrodes for supercapacitor applications

This work presents the first demonstration of atomic layer deposition (ALD) ruthenium oxide (RuO
₂
) and its conformal coating onto vertically aligned carbon nanotube (CNT) forests as supercapacitor electrodes. Specific accomplishments include: (1) successful demonstration of ALD RuO
₂
deposition, (2) uniform coating of RuO
₂
on a vertically aligned CNT forest, and (3) an ultra-high specific capacitance of 100 mF/cm
²
from prototype electrodes with a scan rate of 100 mV/s. Advantages of the ALD method include precise control of the RuO
₂
layer thickness and composition without the use of CNT-binder molecules. In addition to high capacitance, preliminary results indicate that the ALD RuO
₂
-CNTs have good stability over repeated cycling. Besides its use in supercapacitors, ALD-RuO
₂
has potential NEMS applications: in biosensors and pH sensing [1], as a strong oxidative material in multiple chemical processes [2], and in catalytic reactions for photocatalytic systems [3].