MWCNT‐Assisted Integrated Architecture of CoMn ₂ O ₄ /CoP ₂ /MnP Hybrid Catalyst for High‐Energy‐Density Supercapacitors and Enhanced Bifunctional Electrocatalytic HER/OER Activity

ABSTRACT Due to the attractive attributes of oxide and phosphide materials, the present work aims at synthesizing CoMnO/CoP/MnP/MWCNT composite and employed as an electrode for supercapacitor and water splitting applications. The hybrid composite has been synthesized via hydrothermal technique followed by phosphorization. The prepared catalyst has shown a mixed‐phase structure, as confirmed by X‐ray diffraction (XRD), resembling CoMn ₂ O ₄ /CoP ₂ /MnP. The electrochemical investigation for CoMnO/CoP/MnP/MWCNT composite possesses a substantially higher specific capacitance (C _s ) of 748 F/g at 1 A/g and maintained (96.3% stability @ 15 A/g after 5100 cycles), outperforming bare CoMnO/CoP/MnP (424 F/g). The fabricated asymmetric device CoMnO/CoP/MnP/MWCNT//MWCNT also exhibits an Energy Density (ED) of 115.2 Wh/kg at a massive Power Density (PD) of 1920 W/kg, and it upheld impressive stability (95.71% @ 15 A/g after 5100 cycles). Likewise, this catalyst achieves stunning electrocatalytic bifunctional activity in 1 M KOH for HER/OER overpotential of 104 mV/ 319 mV at 10 mA/cm ² with the Tafel slope of (135 / 99) mV/dec and it has a double layer capacitance (C _dl ) value of 92.89 mF/cm ² . Our findings suggest that CoMnO/CoP/MnP/MWCNT is a promising low‐cost electrode material for hybrid supercapacitors alongside a water splitting catalyst because their synergistic features lower the impedance, resulting in faster ion diffusion rates.