Bimetallic RuPc-Co/g-C3N4 based electrode materials for supercapacitor applications: Boosting supercapacitor performance with CO2 utilization

With the need for high energy and corresponding climate change, the world demands sustainable development that relies on efficient energy storage devices to use renewable energy resources. Thus, supercapacitors, to store energy and deliver high power with longer cyclability, serve a crucial role that mainly depends on electrode materials. This study proposes an efficient electrode material based on ruthenium phosphide complex (RuPc) and cobalt-assisted g-C 3 N 4 composite for enhancing supercapacitor performance. The resulting composite (RuPc-Co/g-C 3 N 4 ) exhibited a flaky, layered rod-like morphology for the enhanced electron transfer and abundant active sites for the redox reactions and hence, charge storage. In a 3-electrode system, g-C 3 N 4 , Co/g-C 3 N 4 , and RuPc-Co/g-C 3 N 4 exhibited a specific capacitance of 151, 337, and 568 F g −1 in 3 M KOH. Further, the CO 2 adsorption with KOH electrolyte proved to be beneficial in terms of enhancing the specific capacitance along with capacitance retention. When RuPc-Co/g-C 3 N 4 was used as electrode material in a 3 M KOH electrolyte, a specific capacitance of 568.55 F g −1 was observed, which increased to 777.78 F g −1 when the electrolyte was supplied with CO 2 gas. This enhanced specific capacitance is attributed to the formation of carbonate and bicarbonate species in the electrolyte that improves the redox activity and charge transfer on the electrode surface. The comparison of electrochemically active surface area (ECSA) of g-C 3 N 4 , Co/g-C 3 N 4 , and RuPc-Co/g-C 3 N 4 in 3 M KOH was observed to be 27.5, 42, and 356.5 m 2 g −1 , while CO 2 adsorbed 3 M KOH electrolyte resulted in increased ECSA of 178.25, 194.75, and 422.75 m 2 g −1 . Moreover, the capacitance retention is also improved in CO 2 -enriched electrolyte from 87% to 91% which shows enhanced stability of RuPc-Co/g-C 3 N 4 . Overall, this study demonstrates the use of CO 2 -based electrolytes and RuPc-Co/g-C 3 N 4 electrode materials for high-performance supercapacitor applications, resulting in a CO 2 combating strategy and efficient energy storage.