Tweaking the electrochemical potential of nitrogen-rich Ce-PTA-MOF with reduced graphene oxide for use as a hybrid supercapacitor

Abstract

The scarcity of efficient energy storage devices (ESDs) demands the design of hybrid supercapacitors that integrate the properties of batteries and supercapacitors into one unit. Amongst the various known electrode materials, metal–organic frameworks (MOFs), due to their high porosity and unique electrochemical features, have come forward to boost the electrochemical performance of ESDs. However, the low conductivity of MOFs hinders their practical applications, and researchers are trying to address this issue by designing various strategies that unlock their extraordinary potential. In this work, the conductivity of Ce-PTA-MOF derived from cerium and pyridine-2,4,6-tricarboxylic acid was tweaked by using different amounts of reduced graphene oxide (rGO). Analysis of the electrochemical performance in a three-electrode set up showed that the composite of Ce-PTA-MOF and rGO with a 1 : 2 ratio possessed a significant specific capacity of 689.56 C g⁻¹ which indicated its suitability for use in practical applications. Hence, a hybrid supercapacitor was fabricated from Ce-PTA-MOF@rGO and activated carbon (AC) which exhibited a specific capacity of 380.83 C g⁻¹, a specific energy of 74 W h kg⁻¹ and a specific power of 434 W kg⁻¹ at 0.5 A g⁻¹. A coulombic efficiency of 99% was recorded even after 5000 GCD cycles. The remarkable stability and high specific energy and power density proved that this synthesized composite is a viable option for use in future energy storage devices.