Hybrid heterostructured Langmuir-Blodgett films based on graphene and triruthenium clusters as electrode for energy storage devices

The design of electrodes with highly exposed electroactive sites and improved charge transport that overcomes the current limitations of pseudocapacitors may result in electrodes with high capacity at high rates. These energy storage electrodes are interesting and may have applications as micro-supercapacitors for wearable and implantable devices. Herein, hybrid heterostructured thin film electrodes based on triruthenium clusters and graphene were constructed using the Langmuir-Blodgett (LB) technique. The hybrid thin film performance as supercapacitor electrode was demonstrated in a three-electrode set-up and in asymmetric supercapacitors using graphene as negative electrode and B-PVA-KCl as electrolyte. The hybrid heterostructured LB films exhibited high efficiency as active material and excellent performance at high rates. It led to a better device performance as compared with devices using just triruthenium cluster LB films, achieving a capacitance of 0.710 ​mF ​cm⁻² for an 8-monolayer hybrid heterostructured thin film, which is comparable to other graphene metal oxide hybrid electrodes. This performance was attributed to improved charge transport due to the organized heterostructured LB structure and contributions of both faradaic fast redox reaction from ruthenium(II/III) centers and high double-layer capacitance of the graphene sheets.