Enhancing the electrochemical performance of manganese oxide thin film electrodes via borax incorporation: Experimental and theoretical insights

As global energy demand continues to rise, high-performance supercapacitors emerge as a key focus due to their superior power density and rapid charge-discharge efficiency. To this end, the study explores the synthesis of Mn₃O₄ thin film electrodes incorporated with borax via the spray pyrolysis technique. Structural characterizations reveal that the borax incorporated films preserve the tetragonal Mn₃O₄ phase, indicating its successful integration into the Mn₃O₄ matrix. Surface analysis reveals significant morphological changes, showing dense wrinkles and sodium agglomerations along with increased surface roughness and decreased contact angle after borax incorporation. X-ray photoelectron spectroscopy confirms boron incorporation at interstitial sites, along with oxygen imbalance and changes in the oxidation states of manganese. Electrochemical investigations demonstrate a significant improvement in the specific capacitance and charge-discharge stability of borax-incorporated Mn₃O₄ electrodes, attributed to the enhanced conductivity and optimized electronic structure induced by boron doping. This is again reflected in impedance spectroscopy where a reduced charge transfer resistance is observed in borax-incorporated electrodes. The highest electrochemical performance is observed at an optimal B/Mn ratio of 15 at%, highlighting the potential of boron modification as a promising strategy for next-generation supercapacitors. Further, this is supported by density functional theory, which explains the observed increment in quantum capacitance value of borax incorporated Mn₃O₄ electrodes. The predicted quantum capacitance using density functional theory agrees well with experimental results. This work not only underscores the viability of borax-incorporated Mn₃O₄ thin films as high-performance electrode materials but also opens new avenues for further research into doped transition metal oxides for sustainable energy storage applications.