Phosphomolybdic acid cluster bridging carbon dots and polyaniline nanofibers for effective electrochemical energy storage

Abstract

A ternary coupling material of phosphomolybdic acid cluster bridging carbon dots and polyaniline (CDs–PMo12–PANI) nanofibers is designed to improve electrochemical performance of PANI. The proton-rich PMo12 bonds with PANI via electrostatic interaction to promote the proton-doping level of PANI. The reversible multi-electron redox reactivity of PMo12 contributes to improving pseudo-capacitance of PANI. PMo12 cluster bonds with carbon dots via chemisorption interaction to achieve the immobilization of hydrosoluble PMo12. PMo12 cluster keeps a bridge connection between polyaniline chain and carbon dots. The good electric conductivity of carbon dots and the distinct bonding interface of CDs–PMo12–PANI contribute to improving rate capability and cycling stability of PANI. CDs–PMo12–PANI achieves high specific capacitance of 479 F g−1 at 1 A g−1, reasonable rate capacitance retention of 69.3% when increasing current density from 0.5 to 10 A g−1 and reasonable cycling capacitance retention of 68.1% after 1000 cycles at 5 A g−1. CDs–PMo12–PANI shows higher electrochemical performance of capacitance, rate capability and cycling stability than PANI, PMo12–PANI and CDs–PANI. All-solid-state flexible supercapacitor based on CDs–PMo12–PANI electrode exhibits high specific capacitance of 118.6 F g−1 and specific energy of 37.1 W h kg−1 at 1 A g−1. A single unit of high-performance supercapacitor can directly drive various electronic devices, indicating effective electrochemical energy storage of CDs–PMo12–PANI.