Hybrid of Benzimidazole-Infused Cobalt Phthalocyanine with Carbon Nanotubes for Supercapacitor and Hydrogen Evolution Reaction

Metal–organic framework (MOF)-based composites are emerging as promising candidates for advanced energy storage and conversion technologies. In this work, a new MOF containing octa-benzimidazole-substituted cobalt phthalocyanine (CoBPc) is synthesized, and its composite with multiwalled carbon nanotubes (MWCNTs) is engineered to evaluate its dual functionality toward supercapacitor performance and hydrogen evolution reaction (HER). The integration of redox-active CoBPc with conductive MWCNTs promotes strong π–π interactions, enhances electron transport, and increases the accessible surface area, collectively improving catalytic behavior. The CoBPc-MWCNT composite exhibits excellent supercapacitive performance, delivering a capacitance of 25 mF, a specific capacity of 500 Fg1–, a current density of 35.2 mA cm–2, an energy density of 69.4 Wh kg–1, and a power density of 844 Wg1–, along with remarkable cycling stability over 4000 cycles and 46.5 h long-term durability in 0.5 M H2SO4. For HER, the hybrid electrode demonstrated a low overpotential of 153 mV at −10 mA cm–2, approaching the performance of standard Pt/C, and a Tafel slope of 39 mV dec–1, indicating fast reaction kinetics. The impedance and ECSA results of the composite substantiate the reduced overpotential, highlighting the influence of enhanced conductivity and abundant active sites. The superior dual performance is attributed to the nitrogen-rich phthalocyanine framework and the conductive carbon network, enabling strong π–π interactions, optimized electron density, and efficient charge transport.