Nitrogen-rich palladium tetra amino-hippuric acid phthalocyanine complex and its hybrid composite with multi-walled carbon nanotubes for supercapacitor application

Supercapacitors are the most attractive alternative energy storage and conversion systems for the future generation to successfully overcome the global energy dilemma. An extensive number of studies have been conducted to enhance the performance of an electrode and to find an appropriate electrolyte for high power density and energy density. However, it is still challenging to develop a suitable electrode/electrolyte system to boost the performance of supercapacitors. Here, a novel nitrogen-rich palladium amide bridge hippuric acid phthalocyanine complex (PdTAHAPc) is synthesized in pure state. The purity and structural characteristics of the synthesized dark green-colored PdTAHAPc are analyzed by various analytical and spectroscopic techniques. To further enhance its performance, PdTAHAPc is combined with multi-walled carbon nanotubes to prepare the PdTAHAPc-MWCNTs hybrid composite. The supercapacitance behavior of the PdTAHAPc-MWCNTs is investigated with respect to that of PdTAHAPc. The hybrid composite electrode exhibits a superior specific capacitance of 245 F·g⁻¹ and 221 F·g⁻¹ at a current density of 0.2 and 1 A·g⁻¹, respectively, in 1.0 M sulfuric acid electrolyte. Furthermore, the developed hybrid composite electrode exhibits an excellent stability towards 5000 electrochemical cycles and a higher capacitance value at 80 °C compared to room temperature. The combination of PdTAHAPc with MWCNTs provides an exceptionally high surface area, leading to a lesser charge transfer resistance and a superior charge storage capacity of the developed PdTAHAPc-MWCNTs hybrid composite.