Abstract
Barium molybdate (BaMoO4) based materials are emerging as stable and environmentally benign electrodes; however, their electrochemical roles and tunability remain insufficiently explored. In this work, pristine and Zn-modified BaMoO4 materials were synthesized via a solid-state chemical route and systematically investigated as complementary electrodes for hybrid supercapacitors. Structural characterization confirms that pristine BaMoO4 crystallizes in a well-defined scheelite-type tetragonal phase with a tetrahedral morphology, whereas Zn doping induces noticeable structural disorder, reduced crystallinity, and the formation of Zn-rich Mo–O regions. Electrochemical studies in 2 M Na2SO4 reveal that pristine BaMoO4 exhibits predominantly electric double-layer capacitive behavior and limited accessible redox sites with excellent cycling stability, making it suitable as a positive electrode. In contrast, Zn-modified BaMoO4 operates effectively in the negative potential region, delivering an enhanced pseudocapacitive response (303 F g−1), attributed to reversible Zn2+-associated redox processes. By pairing these two functionally distinct electrodes, a BaMoO4/Zn-BaMoO4 hybrid supercapacitor was assembled, achieving an extended aqueous operating voltage of 1.8 V and a specific capacitance of 76 F g−1 at 0.33 A g−1, with 87% capacitance retention after 2000 cycles. Rather than maximizing absolute capacitance and energy density values, this study demonstrates a controlled structural modification strategy through Zn dopant in which targeted lattice and morphological changes enable polarity-selective charge storage within an oxide family, offering a stable and sustainable platform for aqueous hybrid energy storage systems.