All Redox-Active 2D MXene and 0D Phosphomolybdic Acid Nanoclusters-Anchored Polypyrrole Nanotubes for High-Performance Aqueous Hybrid Supercapacitors

Abstract

The construction of a hybrid supercapacitor (HSC) with 2D Ti3C2Tx MXene anode is restricted by the scarcity of promising cathode materials that can demonstrate the superior electro-chemical features in protic electrolytes. To circumvent this issue, we demonstrate an innovative high-performance HSC cell in a protic electrolyte by combining a redox-active 0D phosphomolybdic acid (PMo12) nanoclusters-anchored polypyrrole nano-tubes (PMo12/PPyNT) cathode against the pseudocapacitive Ti3C2Tx MXene anode. Decorating PMo12, a Keggin-type poly-oxometalates material known for their high redox activities on polypyrrole nanotubes (PPyNT) resulting in a nanocomposite that matches the electrochemical performance of MXene in a protic electrolyte so that a high-performance HSC cell can be acquired. The gathered PMo12/PPyNT//MXene HSC cell delivers the specific energy (36.1 Wh/kg) and specific power (6.66 kW/kg) superior to the state-of-the-art MXene-based supercapacitor (SC) cells. The cell also exhibits impressive coulombic efficiencies over various current densities and adequate stability over 5000 charge-discharge cycles. These results show that combining polyoxomolybdate-based cathode materials against the MXene anode can overcome the boundaries associated with the existing HSC cells.