Investigating the electrochemical performance of Mn3O4/MoMn2P12 mixed-phase catalyst on MWCNT for high specific energy supercapacitors and HER/OER reactions

Abstract

A versatile Mn/MoMn hybrid oxide/phosphide composite (MnO/MoMnP) supported on MWCNT is synthesized using hydrothermal method and in-situ phosphorization methods. This composite serves as a catalyst for supercapacitors and oxygen and hydrogen evolution reactions (OER/HER) in electrochemical water splitting. XRD analysis confirmed the presence of mixed-phase of Mn3O4 and MoMn2P12. Electrochemical tests revealed exceptional charge storage performance for MnO/MoMnP/MWCNT, with a high specific capacitance(436 F g−1 at 1 A g−1) and impressive capacitance retention (96.51 % for 5000 cycles at 15 A g−1). This performance surpasses that of bare MnO/MoMnP by 50 %. Furthermore, we assembled a MnO/MoMnP/MWCNT//MWCNT device, that achieved a remarkable energy density of 128.11 W h kg−1 at an ultra-high-power density of 1920 W kg−1, along with excellent cycling stability (92.5 % for 5000 cycles). Moreover, the MnO/MoMnP/MWCNT composite exhibited a remarkable bifunctional electro catalytic activity for OER and HER, with low overpotentials of 335 and 430 mV at 10 mA cm−2 in 1 M KOH solution. These results highlight MnO/MoMnP/MWCNT as a promising and efficient alternative catalyst for future applications in supercapacitors and water electrolysis.