Suppress oxygen ordering for the design of hollow bimetallic oxide sphere-based photo-charged energy storage and high-frequency filtering capacitors

Engineering defects in the lattice of the metal vanadates are a potential approach to modify the electronic structure and enhance interfacial charge dynamics. We present oxygen-deficient BiVO 4 (Vo–BiVO 4 ) with a uniform hollow interior using different treatment methods (i.e., solution, electrochemical, and high-temperature exposure). The imbalance in the outward movement of oxygen, the rearrangement of Bi and V, and the rapid formation of the Vo result in supersaturated vacancies, thereby enabling potent photo charge storage and a high-capacitance filtering capacitor. The optimized Vo–BiVO 4 (NaBH 4 ) electrode delivers a specific capacitance above 1100 F g −1 in a three-electrode system, while the assembled Vo–BiVO 4 (NaBH 4 )//AC device achieves 289.37 F g −1 at 1 A g −1 under illumination, and maintains around 88% of its initial capacitance after 5000 cycles with nearly 100% coulombic efficiency. In addition, a photo-charged asymmetric device (Vo–BiVO 4 //AC) achieves an energy density of 49.21 Wh kg −1 under illumination, significantly surpassing its dark-state performance and exceeding that of leading BiVO 4 -based systems. The electrode demonstrates exceptional cycling durability. In addition to photo-charging, the Vo-BiVO 4 exhibits remarkably low-resistance filtering capacitor performance, achieving a Bode phase angle of −80° and an areal capacitance of approximately 2.43 mF cm −2 at 120 Hz, highlighting its rapid frequency response and minimal resistive loss.