Synergistic effect of Mo doping on the pseudocapacitive performance of Zn–V–O based TMOs for supercapacitor applications

Abstract

Supercapacitors (SCs) are crucial for meeting the growing demand for energy. The development of next-generation SCs still depends on the evolution of high-performance electrode materials. Compared with single component metal oxides, ternary metal oxides (TMOs) offer multiple oxidation states and superior supercapacitive performance. The rational design and doping of complex metal oxides offer a powerful strategy to overcome the performance limitations of supercapacitors (SCs). This work presents pure and Mo-doped ZnV₂O₄ ternary metal oxides (Mo-TMOs) with tailored nanostructures synthesized by a hydrothermal method to optimize the electrochemical performance for SC applications. The synthesized materials were used for assembling a symmetric SC device. Comprehensive structural and morphological analyses confirm a uniform Mo distribution and the formation of highly interconnected nanostructures that promote rapid ion diffusion and electron transport. The prepared ZnV₂O₄ and ZnV_0.98Mo_0.02O₂ deliver excellent specific capacitances of 697.14 F g⁻¹ and 752.08 F g⁻¹ at 5 mV s⁻¹, respectively. The fabricated device possesses a high energy density of 34.85 Wh kg⁻¹ at a power density of 313.71 W kg⁻¹ for ZnV₂O₄ and 37.60 Wh kg⁻¹ at a power density of 323.08 W kg⁻¹ for the ZnV_0.98Mo_0.02O₂ sample. Both samples possess high BET surface areas of 77.25 and 100.42 m² g⁻¹. Moreover, the fabricated device exhibits excellent cyclic stability of 96.1% for the pure sample and 97.2% for the Mo-doped sample at 5 A g⁻¹ after 10 000 cycles. Incorporation of Mo into the ternary oxide framework successfully tunes the electronic conductivity, increases the redox activity and enhances the structural stability, indicating promising SC performances for future prospects.