Photoenhanced supercapacitance in fractal silicon nanowire-based arrays

Sustainable energy technologies necessitate efficient and reliable energy-storage systems complementing renewable energy generation. Supercapacitors offer superior power density and cycling stability, making them indispensable for high-power applications. Silicon, the cornerstone of microelectronics, is an earth-abundant material whose nanostructured forms, particularly silicon nanowires (SiNWs), exhibit promising electrochemical and optoelectronic properties. Here we report the fabrication and characterization of fractal and quantum confined SiNW-based supercapacitors exhibiting a fourfold enhancement in specific capacitance under simulated solar illumination. Electrochemical measurements reveal typical non-faradic behavior, with specific capacitance increasing from ≈300 μF/cm 2 in the dark to ≈1.2 mF/cm 2 under illumination. The results highlight the potential of SiNWs as photocapacitors for next-generation electrochemical energy-storage devices.